Researchers Database

SAEKI Kazuhiko

    Faculty Division of Natural Sciences Research Group of Biological Sciences Professor
Contact:
ksaekicc.nara-wu.ac.jp
Last Updated :2021/07/07

researchmap

Research Interests

  • Nitrogen fixation, Symbiosis, Plant-Microbe interaction, Protein secretion 

Research Areas

  • Life sciences, Functional biochemistry
  • Life sciences, Plants: molecular biology and physiology

Research Experience

  • Apr. 2012, Professor, School of Natural Sciences, Nara Women's University
  • Oct. 2004 Mar. - 2012, Professor, Department of Biological Science, Nara Women's University
  • May 2000 Sep. - 2004, Associate Professor, Department of Biology, Graduate School of Science, Osaka University
  • Apr. 1996 Apr. - 2000, Lecturer, Department of Biology, Graduate School of Science, Osaka University
  • Jun. 1995 Mar. - 1996, Lecturer, Department of Biology, Faculty of Science, Osaka University
  • Nov. 1989 May - 1995, Instructor, Department of Biology, Faculty of Science, Osaka University
  • Sep. 1987 Oct. - 1989, Instructor, Department of Biology, Faculty of Science, Osaka University
  • Aug. 1986 Aug. - 1987, Visiting Research Associate, Department of Biochemistry, Michigan State University and Michigan Biotechnology Institute, USA

Education

  • - 1986, Osaka University, Graduate School of Science, Course for Biological Chemistry
  • Mar. - 1981, The University of Tokyo, Faculty of Science, Department of Biophysics and Biochemistry

Committee Memberships

  • Jan. 2004 Apr.2005Japanese Society of Plant PhysiologistsTreasurer
  • Jan. 1992 Dec.1993Japanese Society of Plant PhysiologistsSecretary

Published Papers

  • Assessment of Polygala paniculata (Polygalaceae) characteristics for evolutionary studies of legume–rhizobia symbiosis

    Yuji Tokumoto; Kayo Hashimoto; Takashi Soyano; Seishiro Aoki; Wataru Iwasaki; Mai Fukuhara; Tomomi Nakagawa; Kazuhiko Saeki; Jun Yokoyama; Hironori Fujita; Masayoshi Kawaguchi

    Springer Science and Business Media LLC, Jan. 2020, Journal of Plant Research, 133 (1), 109 - 122, doi;url;url

    Scientific journal

  • Lotus Accessions Possess Multiple Checkpoints Triggered by Different Type III Secretion System Effectors of the Wide-Host-Range Symbiont Bradyrhizobium elkanii USDA61.

    Shohei Kusakabe; Nahoko Higasitani; Takakazu Kaneko; Michiko Yasuda; Hiroki Miwa; Shin Okazaki; Kazuhiko Saeki; Atsushi Higashitani; Shusei Sato

    Bradyrhizobium elkanii, a rhizobium with a relatively wide host range, possesses a functional type III secretion system (T3SS) that is involved in symbiotic incompatibility against Rj4-genotype soybean (Glycine max) and some accessions of mung bean (Vigna radiata). To expand our knowledge on the T3SS-mediated partner selection mechanism in the symbiotic legume-rhizobia association, we inoculated three Lotus experimental accessions with wild-type and T3SS-mutant strains of B. elkanii USDA61. Different responses were induced by T3SS in a host genotype-dependent manner. Lotus japonicus Gifu inhibited infection; L. burttii allowed infection, but inhibited nodule maturation at the post-infection stage; and L. burttii and L. japonicus MG-20 both displayed a nodule early senescence-like response. By conducting inoculation tests with mutants of previously reported and newly identified effector protein genes of B. elkanii USDA61, we identified NopF as the effector protein triggering the inhibition of infection, and NopM as the effector protein triggering the nodule early senescence-like response. Consistent with these results, the B. elkanii USDA61 gene for NopF introduced into the Lotus symbiont Mesorhizobium japonicum induced infection inhibition in L. japonicus Gifu, but did not induce any response in L. burttii or L. japonicus MG-20. These results suggest that Lotus accessions possess at least three checkpoints to eliminate unfavorable symbionts, including the post-infection stage, by recognizing different T3SS effector proteins at each checkpoint., 2020, Microbes and environments, 35 (1), False, doi;pubmed

  • Whole-Genome Sequence of the Nitrogen-Fixing Symbiotic Rhizobium Mesorhizobium loti Strain TONO

    Yoshikazu Shimoda; Hideki Hirakawa; Shusei Sato; Kazuhiko Saeki; Makoto Hayashi

    Mesorhizobium loti is the nitrogen-fixing microsymbiont for legumes of the genus Lotus . Here, we report the whole-genome sequence of a Mesorhizobium loti strain, TONO, which is used as a symbiont for the model legume Lotus japonicus . The whole-genome sequence of the strain TONO will be a solid platform for comparative genomics analyses and for the identification of genes responsible for the symbiotic properties of Mesorhizobium species., American Society for Microbiology, 27 Oct. 2016, Genome Announcements, 4 (5), doi;url

    Scientific journal

  • Peribacteroid solution of soybean root nodules partly induces genomic loci for differentiation into bacteroids of free-living Bradyrhizobium japonicum cells

    Naoko Ohkama-Ohtsu; Sachiko Ichida; Hiroko Yamaya; Takuji Ohwada; Manabu Itakura; Yoshino Hara; Hisayuki Mitsui; Takakazu Kaneko; Satoshi Tabata; Kouhei Tejima; Kazuhiko Saeki; Hirofumi Omori; Makoto Hayashi; Takaki Maekawa; Yoshikatsu Murooka; Shigeyuki Tajima; Kenshiro Simomura; Mika Nomura; Toshiki Uchiumi; Akihiro Suzuki; Yoshikazu Shimoda; Mikiko Abe; Kiwamu Minamisawa; Yasuhiro Arima; Tadashi Yokoyama

    Informa UK Limited, 04 May 2015, Soil Science and Plant Nutrition, 61 (3), 461 - 470, doi;web_of_science;url

    Scientific journal

  • Genome Analysis of a Novel Bradyrhizobium sp. DOA9 Carrying a Symbiotic Plasmid

    Shin Okazaki; Rujirek Noisangiam; Takashi Okubo; Takakazu Kaneko; Kenshiro Oshima; Masahira Hattori; Kamonluck Teamtisong; Pongpan Songwattana; Panlada Tittabutr; Nantakorn Boonkerd; Kazuhiko Saeki; Shusei Sato; Toshiki Uchiumi; Kiwamu Minamisawa; Neung Teaumroong

    Public Library of Science (PLoS), 24 Feb. 2015, PLOS ONE, 10 (2), e0117392 - e0117392, doi;web_of_science;url

    Scientific journal

  • Hijacking of leguminous nodulation signaling by the rhizobial type III secretion system

    S. Okazaki; T. Kaneko; S. Sato; K. Saeki

    Proceedings of the National Academy of Sciences, 15 Oct. 2013, Proceedings of the National Academy of Sciences, 110 (42), 17131 - 17136, doi;web_of_science;url

    Scientific journal

  • LjMATE1: A Citrate Transporter Responsible for Iron Supply to the Nodule Infection Zone of Lotus japonicus

    Kojiro Takanashi; Kengo Yokosho; Kazuhiko Saeki; Akifumi Sugiyama; Shusei Sato; Satoshi Tabata; Jian Feng Ma; Kazufumi Yazaki

    Symbiotic nitrogen fixation by intracellular rhizobia within legume root nodules requires the exchange of nutrients between host plant cells and their resident bacteria. While exchanged molecules imply nitrogen compounds, carbohydrates and also various minerals, knowledge of the molecular basis of plant transporters that mediate those metabolite exchanges is still limited. In this study, we have shown that a multidrug and toxic compound extrusion (MATE) protein, LjMATE1, is specifically induced during nodule formation, which nearly paralleled nodule maturation, in a model legume Lotus japonicus. Reporter gene experiments indicated that the expression of LjMATE1 was restricted to the infection zone of nodules. To characterize the transport function of LjMATE1, we conducted a biochemical analysis using a heterologous expression system, Xenopus oocytes, and found that LjMATE1 is a specific transporter for citrate. The physiological role of LjMATE1 was analyzed after generation of L. japonicus RNA interference (RNAi) lines. One RNAi knock-down line revealed limited growth under nitrogen-deficient conditions with inoculation of rhizobia compared with the controls (the wild type and an RNAi line in which LjMATE1 was not suppressed). It was noteworthy that Fe localization was clearly altered in nodule tissues of the knock-down line. These results strongly suggest that LjMATE1 is a nodule-specific transporter that assists the translocation of Fe from the root to nodules by providing citrate. © 2013 The Author 2013. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com., Oxford University Press (OUP), Apr. 2013, Plant and Cell Physiology, 54 (4), 585 - 594, doi;pubmed;url

    Scientific journal

  • Commonalities and differences among symbiosis islands of three Mesorhizobium loti strains.

    Hiroko Kasai-Maita; Hideki Hirakawa; Yasukazu Nakamura; Takakazu Kaneko; Kumiko Miki; Jumpei Maruya; Shin Okazaki; Satoshi Tabata; Kazuhiko Saeki; Shusei Sato

    To shed light on the breadth of the host range of Mesorhizobium loti strain NZP2037, we determined the sequence of the NZP2037 symbiosis island and compared it with those of strain MAFF303099 and R7A islands. The determined 533 kb sequence of NZP2037 symbiosis island, on which 504 genes were predicted, implied its integration into a phenylalanine-tRNA gene and subsequent genome rearrangement. Comparative analysis revealed that the core regions of the three symbiosis islands consisted of 165 genes. We also identified several NZP2037-specific genes with putative functions in nodulation-related events, suggesting that these genes contribute to broaden the host range of NZP2037., 2013, Microbes and environments, 28 (2), 275 - 8, False, doi;pubmed;pmc

  • Involvement of a Novel Genistein-Inducible Multidrug Efflux Pump of Bradyrhizobium japonicum Early in the Interaction with Glycine max (L.) Merr

    Keisuke Takeshima; Tatsuo Hidaka; Min Wei; Tadashi Yokoyama; Kiwamu Minamisawa; Hisayuki Mitsui; Manabu Itakura; Takakazu Kaneko; Satoshi Tabata; Kazuhiko Saeki; Hirofumi Oomori; Shigeyuki Tajima; Toshiki Uchiumi; Mikiko Abe; Yoshihiko Tokuji; Takuji Ohwada

    Japanese Society of Microbial Ecology, 2013, Microbes and Environments, 28 (4), 414 - 421, doi;web_of_science

    Scientific journal

  • Rhizobial measures to evade host defense strategies and endogenous threats to persistent symbiotic nitrogen fixation: a focus on two legume-rhizobium model systems

    Kazuhiko Saeki

    The establishment and maintenance of rhizobium-legume symbioses require a sequence of highly regulated and coordinated events between the organisms. Although the interaction is mutually beneficial under nitrogen-limited conditions, it can resemble a pathogenic infection at some stages. Some host legumes mount defense reactions, including the production of reactive oxygen species (ROS) and defensin-like antimicrobial compounds. To subvert these host defenses, the infecting rhizobial cells can use measures to passively protect themselves and actively modulate host functions. This review first describes the establishment and maintenance of active nodules, as well as the external and endogenous attack and threat stages. Next, recent studies of ROS scavenging enzymes, the BacA protein originally found in Sinorhizobium meliloti, and the type III/IV secretion systems are discussed, with a focus on two legume-rhizobium model systems., SPRINGER BASEL AG, Apr. 2011, CELLULAR AND MOLECULAR LIFE SCIENCES, 68 (8), 1327 - 1339, doi;web_of_science

  • The bacA Gene Homolog, mlr7400, in Mesorhizobium loti MAFF303099 is Dispensable for Symbiosis with Lotus japonicus but Partially Capable of Supporting the Symbiotic Function of bacA in Sinorhizobium meliloti

    Jumpei Maruya; Kazuhiko Saeki

    Establishment of rhizobiumlegume symbiosis requires a series of mutual authentication, which might involve bacterial evasion of host defense. One such evasion-related genes is Sinorhizobium meliloti bacA that is essential for bacteroid formation. BacA is a transmembrane protein highly similar to Escherichia coli SbmA, a predicted transporter, and has homologs even in animal pathogens, such as Brucella abortus in which the homolog contributes to effective survival in host macrophages. Despite such a significance in hostmicrobe interactions, studies on rhizobial BacA have been mostly performed with the MedicagoSinorhizobium model system that forms indeterminate cylindrical nodules. Since Lotus japonicusMesorhizobium loti constitutes another model system that forms determinate globular nodules, we genetically analyzed the bacA homolog with the locus tag mlr7400 in M. loti MAFF303099. We found that the mlr7400-null mutant ML7400DK was able to establish quasi-healthy symbiosis with the Lotus plant with 5080 nitrogen-fixing capacity. This dispensability for symbiosis was in contrast to the indispensability of S. meliloti BacA for symbiosis. However, free-living phenotypes of ML7400DK paralleled those of known bacA mutants, i.e. ML7400DK showed decreased sensitivity to the antibiotics bleomycin and gentamicin as well as increased sensitivity to membrane-disturbing reagents such as SDS. Conservation of the free-living function between Mlr7400 protein and S. meliloti BacA was further confirmed by heterologous complementation experiments. Although simple introduction of mlr7400 into the S. meliloti bacA mutant did not increase the symbiotic capacity at all, a significant but marginal increase was obtained when mlr7400 was fused to the S. meliloti bacA promoter. These findings might indicate currently progressing evolutionary specialization among BacASbmA proteins., OXFORD UNIV PRESS, Sep. 2010, PLANT AND CELL PHYSIOLOGY, 51 (9), 1443 - 1452, doi;web_of_science

    Scientific journal

  • Temperature-Dependent Expression of Type III Secretion System Genes and Its Regulation in Bradyrhizobium japonicum

    Min Wei; Keisuke Takeshima; Tadashi Yokoyama; Kiwamu Minamisawa; Hisayuki Mitsui; Manabu Itakura; Takakazu Kaneko; Satoshi Tabata; Kazuhiko Saeki; Hirofumi Omori; Shigeyuki Tajima; Toshiki Uchiumi; Mikiko Abe; Satoshi Ishii; Takuji Ohwada

    The genome-wide expression profiles of Bradyrhizobium japonicum in response to soybean (Glycine max (L.) Merr.) seed extract (SSE) and genistein were monitored with time at a low temperature (15 degrees C). A comparison with the expression profiles of the B. japonicum genome previously captured at the common growth temperature (30 degrees C) revealed that the expression of SSE preferentially induced genomic loci, including a large gene cluster encoding the type III secretion system (T3SS), were considerably delayed at 15 degrees C, whereas most nodulation (nod) gene loci, including nodD1 and nodW, were rapidly and strongly induced by both SSE and genistein. Induction of the T3SS genes was progressively activated upon the elevation of temperature to 30 degrees C and positively responded to culture population density. In addition, genes nolA and nodD2 were dramatically induced by SSE, concomitantly with the expression of T3SS genes. However, the deletion mutation of nodD2 but not nolA led to elimination of the T3SS genes expression. These results indicate that the expression of the T3SS gene cluster is tightly regulated with integration of environmental cues such as temperature and that NodD2 may be involved in its efficient induction in B. japonicum., AMER PHYTOPATHOLOGICAL SOC, May 2010, MOLECULAR PLANT-MICROBE INTERACTIONS, 23 (5), 628 - 637, doi;web_of_science

    Scientific journal

  • Identification and Functional Analysis of Type III Effector Proteins in Mesorhizobium loti

    Shin Okazaki; Saori Okabe; Miku Higashi; Yoshikazu Shimoda; Shusei Sato; Satoshi Tabata; Masatsugu Hashiguchi; Ryo Akashi; Michael Goettfert; Kazuhiko Saeki

    Mesorhizobium loti MAFF303099, a microsymbiont of the model legume Lotus japonicus, possesses a cluster of genes (tts) that encode a type III secretion system (T3SS). In the presence of heterologous nodD from Rhizobium leguminosarum and a flavonoid naringenin, we observed elevated expression of the tts genes and secretion of several proteins into the culture medium. Inoculation experiments with wild-type and T3SS mutant strains revealed that the presence of the T3SS affected nodulation at a species level within the Lotus genus either positively (L. corniculatus subsp. frondosus and L. filicaulis) or negatively (L. halophilus and two other species). By inoculating L. halophilus with mutants of various type III effector candidate genes, we identified open reading frame mlr6361 as a major determinant of the nodulation restriction observed for L. halophilus. The predicted gene product of mlr6361 is a protein of 3,056 amino acids containing 15 repetitions of a sequence motif of 40 to 45 residues and a shikimate kinase-like domain at its carboxyl terminus. Homologues with similar repeat sequences are present in the hypersensitive-response and pathogenicity regions of several plant pathogens, including strains of Pseudomonas syringae, Ralstonia solanacearum, and Xanthomonas species. These results suggest that L. halophilus recognizes Mlr6361 as potentially pathogen derived and subsequently halts the infection process., AMER PHYTOPATHOLOGICAL SOC, Feb. 2010, MOLECULAR PLANT-MICROBE INTERACTIONS, 23 (2), 223 - 234, doi;web_of_science

    Scientific journal

  • Functional Differences of Two Distinct Catalases in Mesorhizobium loti MAFF303099 under Free-Living and Symbiotic Conditions

    Masaki Hanyu; Hanae Fujimoto; Kouhei Tejima; Kazuhiko Saeki

    Protection against reactive oxygen species (ROS) is important for legume-nodulating rhizobia during the establishment and maintenance of symbiosis, as well as under free-living conditions, because legume hosts might assail incoming microbes with ROS and because nitrogenase is extremely sensitive to ROS. We generated mutants of two potential catalase genes in Mesorhizobium loti MAFF303099 to investigate their physiological significance. Biochemical results indicated that genes with the locus tags mlr2101 and mlr6940 encoded a monofunctional catalase and a bifunctional catalase-peroxidase, respectively, that were named katE and katG. Under free-living conditions, the katG mutant demonstrated an extended generation time and elevated sensitivity to exogenous H2O2, whereas the katE mutant exhibited no generation time extension and only a slight increase in sensitivity to exogenous H2O2. However, the katE mutant showed a marked decrease in its survival rate during the stationary phase. With regard to symbiotic capacities with Lotus japonicus, the katG mutant was indistinguishable from the wild type; nevertheless, the mutants with disrupted katE formed nodules with decreased nitrogen fixation capacities (about 50 to 60%) compared to those formed by the wild type. These mutant phenotypes agreed with the expression profiles showing that transcription of katG, but not katE, was high during the exponential growth phase and that transcription levels of katE versus sigA were elevated during stationary phase and were approximately fourfold higher in bacteroids than mid-exponential-phase cells. Our results revealed functional separation of the two catalases, as well as the importance of KatE under conditions of strong growth limitation., AMER SOC MICROBIOLOGY, Mar. 2009, JOURNAL OF BACTERIOLOGY, 191 (5), 1463 - 1471, doi;web_of_science

    Scientific journal

  • Genomic comparison of Bradyrhizobium japonicum strains with different symbiotic nitrogen-fixing capabilities and other Bradyrhizobiaceae members

    Manabu Itakura; Kazuhiko Saeki; Hirofumi Omori; Tadashi Yokoyama; Takakazu Kaneko; Satoshi Tabata; Takuji Ohwada; Shigeyuki Tajima; Toshiki Uchiumi; Keina Honnma; Konosuke Fujita; Hiroyoshi Iwata; Yuichi Saeki; Yoshino Hara; Seishi Ikeda; Shima Eda; Hisayuki Mitsui; Kiwamu Minamisawa

    Comparative genomic hybridization (CGH) was performed with nine strains of Bradyrhizobium japonicum (a symbiotic nitrogen-fixing bacterium associated with soybean) and eight other members of the Bradyrhizobiaceae by DNA macroarray of B. japonicum USDA110. CGH clearly discriminated genomic variations in B. japonicum strains, but similar CGH patterns were observed in other members of the Bradyrhizobiaceae. The most variable regions were 14 genomic islands (4-97 kb) and low G + C regions on the USDA110 genome, some of which were missing in several strains of B. japonicum and other members of the Bradyrhizobiaceae. The CGH profiles of B. japonicum were classified into three genome types: 110, 122 and 6. Analysis of DNA sequences around the boundary regions showed that at least seven genomic islands were missing in genome type 122 as compared with type 110. Phylogenetic analysis for internal transcribed sequences revealed that strains belonging to genome types 110 and 122 formed separate clades. Thus genomic islands were horizontally inserted into the ancestor genome of type 110 after divergence of the type 110 and 122 strains. To search for functional relationships of variable genomic islands, we conducted linear models of the correlation between the existence of genomic regions and the parameters associated with symbiotic nitrogen fixation in soybean. Variable genomic regions including genomic islands were associated with the enhancement of symbiotic nitrogen fixation in B. japonicum USDA110., NATURE PUBLISHING GROUP, Mar. 2009, ISME JOURNAL, 3 (3), 326 - 339, doi;web_of_science

    Scientific journal

  • Soybean Seed Extracts Preferentially Express Genomic Loci of Bradyrhizobium japonicum in the Initial Interaction with Soybean, Glycine max (L.) Merr

    Min Wei; Tadashi Yokoyama; Kiwamu Minamisawa; Hisayuki Mitsui; Manabu Itakura; Takakazu Kaneko; Satoshi Tabata; Kazuhiko Saeki; Hirofumi Omori; Shigeyuki Tajima; Toshiki Uchium; Mlkiko Abe; Takuji Ohwada

    Initial interaction between rhizobia and legumes actually starts via encounters of both partners in the rhizosphere. In this study, the global expression profiles of Bradyrhizobium japonicum USDA 110 in response to soybean (Glycine max) seed extracts (SSE) and genistein, a major soybean-released isoflavone for nod genes induction of B. japonicum, were compared. SSE induced many genomic loci as compared with genistein (5.0 mu M), nevertheless SSE-supplemented medium contained 4.7 mu M genistein. SSE markedly induced four predominant genomic regions within a large symbiosis island (681 kb), which include tts genes (type III secretion system) and various nod genes. in addition, SSE-treated cells expressed many genomic loci containing genes for polygalacturonase (cell-wall degradation), exopolysaccharide synthesis, 1-aminocyclopropane-1-carboxylate deaminase, ribosome proteins family and energy metabolism even outside symbiosis island. On the other hand, genistein-treated cells exclusively showed one expression cluster including common nod gene operon within symbiosis island and six expression loci including multidrug resistance, which were shared with SSE-treated cells. Twelve putatively regulated genes were indeed validated by quantitative RT-PCR. Several SSE-induced genomic loci likely participate in the initial interaction with legumes. Thus, these results can provide a basic knowledge for screening novel genes relevant to the B. japonicum- soybean symbiosis., OXFORD UNIV PRESS, Aug. 2008, DNA RESEARCH, 15 (4), 201 - 214, doi;web_of_science

    Scientific journal

  • Requirement for Mesorhizobium loti ornithine transcarbamoylase for successful symbiosis with Lotus japonicus as revealed by an unexpected long-range genome deletion

    Elina Mishima; Atsuko Hosokawa; Haruko Imaizumi-Anraku; Katsuharu Saito; Masayoshi Kawaguchi; Kazuhiko Saeki

    With the original aim of surveying the role of exopolysaccharide (EPS) in LotusMesorhizobium symbiosis, we carried out Tn5 mutagenesis of Mesorhizobium loti and obtained 32 mutants with defects in EPS biosynthesis. One of the mutants, HIA22, formed pseudonodules and failed to fix nitrogen with Lotus japonicus. However, complementation analysis unexpectedly revealed that the potential gene with the locus tag, mll2073, interrupted by Tn5 was responsible for neither normal EPS synthesis nor symbiosis. Further analysis uncovered that HIA22 had a genome deletion of approximately 20 kbp, resulting in the loss of two separate genes responsible for EPS biosynthesis and symbiosis. One gene with the locus tag, mll5669, was needed to synthesize normal EPS that fluoresced on medium containing Calcofluor and encoded a homolog of O-antigen acetyl transferase in Salmonella typhimurium. A specific mutant of mll5669, EMB-B58, successfully fixed nitrogen when infected onto L. japonicus. Another gene, mlr5647, was needed to establish fully functional nodules and encoded ornithine carbamoyl transferase [ArgF (EC 2.1.3.3)], which participates in arginine biosynthesis. A specific mutant of mlr5647, EMB-Y2, showed arginine auxotrophy and formed infection threads, but the nodules formed by this strain had few infected cells filled with bacteroids. These mutant phenotypes were complemented by supplementation of arginine or citrulline to bacterial or plant medium. EMB-Y2 represented a novel class of rhizobial arginine auxotrophs with symbiotic deficiency, and its phenotypes indicated that sufficient supply of citrulline or its derivative is essential for successful infection or for a stage in the infection process in LotusMesorhizobium symbiosis., OXFORD UNIV PRESS, Mar. 2008, PLANT AND CELL PHYSIOLOGY, 49 (3), 301 - 313, doi;web_of_science

    Scientific journal

  • The Mesorhizobium loti purB gene is involved in infection thread formation and nodule development in Lotus japonicus

    Shin Okazaki; Yoshiyuki Hattori; Kazuhiko Saeki

    The purB and purH mutants of Mesorhizobium loti exhibited purine auxotrophy and nodulation deficiency on Lotus japonicus. In the presence of adenine, only the purH mutant induced nodule formation and the purB mutant produced few infection threads, suggesting that 5-aminoimidazole-4-carboxamide ribonucleotide biosynthesis catalyzed by PurB is required for the establishment of symbiosis., AMER SOC MICROBIOLOGY, Nov. 2007, JOURNAL OF BACTERIOLOGY, 189 (22), 8347 - 8352, doi;web_of_science

    Scientific journal

  • Rhizobial networks for symbiosis with legumes

    Kiwamu Minamisawa; Kazuhiko Saeki; Shusei Sato; Yoshikazu Shimoda

    01 Aug. 2006, Tanpakushitsu kakusan koso. Protein, nucleic acid, enzyme., 51, 1044 - 1050, pubmed;url

  • Global Gene Expression in Bradyrhizobium japonicum Cultured with Vanillin, Vanillate, 4-Hydroxybenzoate and Protocatechuate

    Naofumi Ito; Manabu Itakura; Shima Eda; Kazuhiko Saeki; Hirofumi Oomori; Tadashi Yokoyama; Takakazu Kaneko; Satoshi Tabata; Takuji Ohwada; Shigeyuki Tajima; Toshiki Uchiumi; Eiji Masai; Masataka Tsuda; Hisayuki Mitsui; Kiwamu Minamisawa

    Japanese Society of Microbial Ecology, 2006, Microbes and Environments, 21 (4), 240 - 250, doi

    Scientific journal

  • Characterization of the Lotus japonicus Symbiotic Mutant lot1 That Shows a Reduced Nodule Number and Distorted Trichomes

    Yasuhiro Ooki; Mari Banba; Koji Yano; Jumpei Maruya; Shusei Sato; Satoshi Tabata; Kazuhiko Saeki; Makoto Hayashi; Masayoshi Kawaguchi; Katsura Izui; Shingo Hata

    American Society of Plant Biologists (ASPB), Apr. 2005, Plant Physiology, 137 (4), 1261 - 1271, doi;web_of_science;url

    Scientific journal

  • Expression Islands Clustered on the Symbiosis Island of the Mesorhizobium loti Genome

    Toshiki Uchiumi; Takuji Ohwada; Manabu Itakura; Hisayuki Mitsui; Noriyuki Nukui; Pramod Dawadi; Takakazu Kaneko; Satoshi Tabata; Tadashi Yokoyama; Kouhei Tejima; Kazuhiko Saeki; Hirofumi Omori; Makoto Hayashi; Takaki Maekawa; Rutchadaporn Sriprang; Yoshikatsu Murooka; Shigeyuki Tajima; Kenshiro Simomura; Mika Nomura; Akihiro Suzuki; Yoshikazu Shimoda; Kouki Sioya; Mikiko Abe; Kiwamu Minamisawa

    ABSTRACT Rhizobia are symbiotic nitrogen-fixing soil bacteria that are associated with host legumes. The establishment of rhizobial symbiosis requires signal exchanges between partners in microaerobic environments that result in mutualism for the two partners. We developed a macroarray for Mesorhizobium loti MAFF303099, a microsymbiont of the model legume Lotus japonicus, and monitored the transcriptional dynamics of the bacterium during symbiosis, microaerobiosis, and starvation. Global transcriptional profiling demonstrated that the clusters of genes within the symbiosis island (611 kb), a transmissible region distinct from other chromosomal regions, are collectively expressed during symbiosis, whereas genes outside the island are downregulated. This finding implies that the huge symbiosis island functions as clustered expression islands to support symbiotic nitrogen fixation. Interestingly, most transposase genes on the symbiosis island were highly upregulated in bacteroids, as were nif, fix, fdx, and rpoN. The genome region containing the fixNOPQ genes outside the symbiosis island was markedly upregulated as another expression island under both microaerobic and symbiotic conditions. The symbiosis profiling data suggested that there was activation of amino acid metabolism, as well as nif-fix gene expression. In contrast, genes for cell wall synthesis, cell division, DNA replication, and flagella were strongly repressed in differentiated bacteroids. A highly upregulated gene in bacteroids, mlr5932 (encoding 1-aminocyclopropane-1-carboxylate deaminase), was disrupted and was confirmed to be involved in nodulation enhancement, indicating that disruption of highly expressed genes is a useful strategy for exploring novel gene functions in symbiosis., American Society for Microbiology, 15 Apr. 2004, Journal of Bacteriology, 186 (8), 2439 - 2448, doi;web_of_science;url

    Scientific journal

  • Characteristic biological activities of lipopolysaccharides from Sinorhizobium and Mesorhizobium

    Y Tsukushi; N Kido; K Saeki; T Sugiyama; N Koide; Mori, I; T Yoshida; T Yokochi

    The biological actions of lipopolysaccharides (LPSs) from Sinorhizobium meliloti, Mesorhizobium loti and Escherichia coli were compared. In biological activities including lethality, production of tumor necrosis factor (TNF)-alpha and nitric oxide (NO), adjuvant action and Limulus activity, LPS from S. meliloti exhibited stronger actions than LPS from M. loti, but had a weaker action than LPS from E. coli. On the other hand, M. loti LPS showed a higher activity to activate human complement than S. meliloti LPS. Further, there was a significant difference in polymyxin B binding between S. meliloti LPS and M. loti LPS, suggesting a difference in the lipid A structure. LPSs from S. meliloti and M. loti seem to exhibit characteristic biological actions that may be dependent on the difference in the lipid A structure., MANEY PUBLISHING, 2004, JOURNAL OF ENDOTOXIN RESEARCH, 10 (1), 25 - 31, doi;web_of_science

    Scientific journal

  • Ordered cosmid library of the Mesorhizobium loti MAFF303099 genome for systematic gene disruption and complementation analysis

    Y Hattori; H Omori; M Hanyu; N Kaseda; E Mishima; T Kaneko; S Tabata; K Saeki

    For effective exploitation of the genome sequence information of Lotus microsymbiont, Mesorhizobium loti MAFF303099, to discover gene functions, we have constructed an ordered and mutually overlapping cosmid library using an IncP broad host-range vector. The library consisted of 480 clones to cover approximately 99.6% of the genome with average insert size and overlap of 26.9 and 11.1 kbp, respectively. The genome of M. loti consists of a single chromosome and two plasmids. The chromosome (7,036,071 bp) was covered 99.68% by 445 clones with four gaps, although two clones were unstable in E. coli. The larger plasmid pMLa (351,911 bp) was completely covered by 23 clones, while the smaller pMLb (208,315 bp) was covered 98.85% by 12 clones with two gaps. We have also made ancillary plasmids to facilitate the construction of deletion mutants using derivatives of the library clones. As a pilot experiment to uncover regions which contain novel symbiotic genes, 13 deletion mutants were constructed to lack in total 180.5 kbp of the genome. All the mutants formed apparently normal nodules and supported symbiotic nitrogen fixation, however, one mutant that lacked a 5.3 kbp chromosomal region, 4,551,930-4,557,222, did not produce normal exopolysaccharides as judged by fluorescence on medium containing Calcofluor. The results supported the effectiveness of the approach to detect gene functions., OXFORD UNIV PRESS, Dec. 2002, PLANT AND CELL PHYSIOLOGY, 43 (12), 1542 - 1557, web_of_science

    Scientific journal

  • A novel bioremediation system for heavy metals using the symbiosis between leguminous plant and genetically engineered rhizobia

    R Sriprang; M Hayashi; M Yamashita; H Ono; K Saeki; Y Murooka

    A novel plant-bacterial remediation system for heavy metals (HM) was developed by expression of tetrameric human metallothionein (MTL4) in Mesorhizobium huakuii subsp. rengei B3, a strain which infects and forms nodules on a green manure, Astragalus sinicus. The MTL4 gene was fused to the nifH and nolB promoters, which generated nodule- specific expression of the MTL4 gene. The expression analysis of the MTL4 gene was demonstrated in free-living cells in the presence of Cd2+ and Cu2+, under the low oxygen condition. The MTL4 under the nifH and nolB promoters was expressed and increased the accumulation of Cd2+, but not Cu2+ in free-living cells. The expression of the integrated nifH-MTL4 gene in the chromosome of strain B3 was also expressed stably and accumulated Cd2+ in the bacterial cells. The MTL4 transcripts were detected by in situ hybridization in bacteroids of mature nodules of A. sinicus containing nifH-MTL4 and nolB-MTL4 fusion gene. Moreover the MTL4 protein was detected by immunostaining. By infection of the recombinant B3, A. sinicus established symbiosis with the recombinant B3 that was grown in Cd2+ and Cu2+-polluted soils. The symbionts increased Cd2+ accumulation in nodules 1.7-2.0-fold, whereas, no significantly increase in Cu2+ accumulation was noted. (C) 2002 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV, Nov. 2002, JOURNAL OF BIOTECHNOLOGY, 99 (3), 279 - 293, web_of_science

    Scientific journal

  • Primary structure and phylogenetic analysis of the coat protein of a Toyama isolate of tobacco necrosis virus

    K Saeki; Y Takahashi; H Oh-Oka; T Umeoka; Y Oda; K Fukuyama

    The amino acid sequence of the coat protein (CP) of a tobacco necrosis virus (TNV) strain, Toyama isolate, was determined by a combination of peptide and cDNA sequencing. The deduced sequence of 276 residues was compared with CPs of other TNV isolates and other plant virus isolates of Tombusviridae. It shelved the highest similarity to the TNV Nebraska isolate with 92% identity and moderate similarity to the TNV strain A with 51% identity, confirming the previous serological analysis. It also showed overall similarity with CPs of mostly genera Necrovirus and Sobemovirus, and partial similarity with CPs of genera Tombusvirus and Carmovirus. Among 13 CPs that showed overall similarity, there were 10 completely conserved residues. These included three residues that participate in Ca2+ ligation at the interfaces of virion subunits in TNV crystal structure, suggesting that similar metal binding occur in the viruses of genera Necrovirus and Sobemovirus., TAYLOR & FRANCIS LTD, Mar. 2001, BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 65 (3), 719 - 724, web_of_science

    Scientific journal

  • The lotus symbiont, Mesorhizobium loti: Molecular genetic techniques and application

    K Saeki; H Kouchi

    Despite the recent attention given to the model legume Lotus japonicus, orderly information on its symbiotic partner Mesorhizobium loti is still lacking. To improve this situation, we review the history of the M. loti nomenclature and compare several strains commonly used, since classification of rhizobia has been confusing during the last decade. We also refer to the large symbiotic gene cluster, the 'symbiosis island', on M. loti chromosome. Then, molecular techniques for M. loti currently available and required to cope with the post-genome sequencing era will be summarized. Finally, we review current knowledge on the structure of M. loti Nod factors., BOTANICAL SOC JAPAN, Dec. 2000, JOURNAL OF PLANT RESEARCH, 113 (1112), 457 - 465, web_of_science

    Scientific journal

  • Crystal structure of tobacco necrosis virus at 2.25 angstrom resolution

    Y Oda; K Saeki; Y Takahashi; T Maeda; H Naitow; T Tsukihara; K Fukuyama

    The crystal structure of tobacco necrosis virus (TNV) has been determined by real-space averaging with 5-fold non-crystallographic symmetry, and refined to R = 25.3 % for diffraction data to 2.25 Angstrom resolution. A total of 180 subunits form a T = 3 virus shell with a diameter of about 280 Angstrom and a small protrusion at the 5-fold axis. In 276 amino acid residues, the respective amino terminal 86, 87 and 56 residues of the A, B and C subunits are disordered. No density for the RNA was found. The subunits have a "jelly roll" beta-barrel structure, as have the structures of the subunits of other spherical viruses. The tertiary and quaternary structures of TNV are, in particular, similar to those of southern bean mosaic virus, although they are classified in different groups. Invisible residues 1 to 56 with a high level of basic residues are considered to be located inside the particle. Sequence comparison of the coat proteins of several TNV strains showed that the sequences of the disordered segment diverge considerably as compared with those of the ordered segment, consistent with a small tertiary structural constraint being imposed on the N-terminal segment. Basic residues are localized on the subunit interfaces or inner surface of the capsid. Positive charges of the basic residues facing the interior, as well as those of the N-terminal segment, may neutralize the negative charge of the RNA inside. Five calcium ions per icosahedral asymmetric unit are located at the subunit interfaces; three are close to the exterior surface, the other two away from it. The environments of the first three are similar, and those of the other two sites are similar. These calcium ions are assumed to be responsible for the stabilization/transition of the quaternary structure of the shell. Three peptide segments ordered only in the C subunits are clustered around each 3-fold (quasi-6-fold) axis forming a beta-annulus, and may lead to quasi-equivalent interactions for the organization of the T = 3 shell. (C) 2000 Academic Press., ACADEMIC PRESS LTD, Jun. 2000, JOURNAL OF MOLECULAR BIOLOGY, 300 (1), 153 - 169, doi;web_of_science

    Scientific journal

  • Hyperproduction of recombinant ferredoxins in Escherichia coli by coexpression of the ORF1-ORF2-iscS-iscU-iscA-hscB-hscA-fdx-ORF3 gene cluster

    M Nakamura; K Saeki; Y Takahashi

    Fe-S proteins acquire Fe-S clusters by an unknown post-translational mechanism. To study the in vivo synthesis of the Fe-S clusters, we constructed an experimental system to monitor the expressed ferredoxin (Fd) as a reporter of protein-bound Fe-S clusters assembled in Escherichia coli, Overexpression of five Fds in a T7 polymerase-based system led to the formation of soluble apoFds and mature holoFds, indicating that assembly of the Fe-S cluster into apoFd polypeptides is a rate-limiting step. We examined the coexpression of the E. coli ORF1-ORF2-iscS-iscU-iscA-hscB-hscA-fdx-ORF3 gene cluster, which has recently been suggested to be involved in the formation or repair of Fe-S protein [Zheng, L., Cash, V.L., Flint, D.H., and Dean, D.R. (1998) J. Biol. Chem. 273, 13264-13272], with reporter Fds using compatible plasmids, The production of all five reporter holoFds examined was dramatically increased by the coexpression of the gene cluster, and apparent specificity to the polypeptides or to the type of Fe-S clusters was not observed. The increase in holoFd production was observed under the coexpression conditions in all culture media examined, with either 2 X YT medium or Terrific broth, and with or without supplemental cysteine or iron. These results indicate that the proteins encoded by the gene cluster are involved in the assembly of the Fe-S clusters in a wide variety of Fe-S proteins., OXFORD UNIV PRESS, Jul. 1999, JOURNAL OF BIOCHEMISTRY, 126 (1), 10 - 18, web_of_science

    Scientific journal

  • The rnf gene products in Rhodobacter capsulatus play an essential role in nitrogen fixation during anaerobic DMSO-dependent growth in the dark

    K Saeki; H Kumagai

    The rnf genes in Rhodobacter capsulatus are essential for nitrogen fixation in the light. Because R. capsulatus grows readily on N-2 in the dark by anaerobic respiration with dimethylsulfoxide, the diazotrophic capacities of various strains in the dark were examined. No I nf mutants tested grew diazotrophically, and a nonpolar fdxN-null mutant showed decreased diazotrophic growth in the dark, suggesting that the Rnf and FdxN proteins form the primary electron donor pathway to nitrogenase in the dark as well as in the light. Nonphotosynthetic mutants lacking the component of cyclic electron transport grew diazotrophically and the levels of Rnf proteins were similar to those of the wild-type. These results indicate that I-nf gene products play an essential role in nitrogen fixation without any functional link to the cyclic electron transport system., SPRINGER VERLAG, May 1998, ARCHIVES OF MICROBIOLOGY, 169 (5), 464 - 467, web_of_science

    Scientific journal

  • Membrane Localization, Topology, and Mutual Stabilization of the rnfABC Gene Products in Rhodobacter capsulatus and Implications for a New Family of Energy-Coupling NADH Oxidoreductases†

    Hirotaka Kumagai; Takeshi Fujiwara; Hiroshi Matsubara; Kazuhiko Saeki

    American Chemical Society (ACS), May 1997, Biochemistry, 36 (18), 5509 - 5521, doi;web_of_science;url

    Scientific journal

  • Site-specific mutagenesis of Rhodobacter capsulatus ferredoxin I, FdxN, that functions in nitrogen fixation - Role of extra residues

    K Saeki; K Tokuda; K Fukuyama; H Matsubara; K Nadanami; M Go; S Itoh

    One of the two [4Fe-4S] type clusters of the Rhodobacter capsulatus ferredoxin I, FdxN, was modified through site-specific mutagenesis of the distinctive features of the second cluster-binding motif, Cys(38)-X(2)-Cys(41)-X(8)-Cys(50)-X(8)-Cys(50)-X(3)-Cys(59). First, various mutagenized products were tested to learn whether they could rescue the decreased capacity of an fdxN-null strain MSA1 to fix nitrogen: the phenotype of MSA1 was reassessed to Nif(s) (slow growth by nitrogen fixation) from our previous description of Nif(-) (Saeki, K., Suetsugu, Y., Tokuda, H., Miyatake, P., Young, D. A., Marrs, B. L. and Matsubara, H. (1991) J. Biol. Chem. 266, 12889-12895). Substitution of Cys(59) to Ser yielded an almost fully active product, while that of Cys(54) did not. Gradual deletions and deletion-substitution of the 8 residues between Cys(41) and Cys(50) also yielded active products. Second, three of the modified FdxN proteins were subjected to purification. Only the GA protein, whose 8 residues between positions 42 and 49 were replaced by the Gly-Ala sequence, was purified. The GA protein and the authentic FdxN showed similar optical properties. The two clusters in the former had E(m) values of -490 and -430 mV, while those in the latter had an identical value of -490 mV, when determined by EPR analysis. It was concluded that: 1) Cys(59) is not a ligand to [4Fe-4S] clusters but is important for structural integrity, 2) the residues between positions 42 and 49 may form a ''loop-out'' from a structure analogous to the Peptococcus aerogenes ferredoxin, and 3) the loop-out region does not have functional significance in nitrogen fixation but may be responsible for maintaining the highly negative redox potential of one of the two clusters., AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, Dec. 1996, JOURNAL OF BIOLOGICAL CHEMISTRY, 271 (49), 31399 - 31406, web_of_science

    Scientific journal

  • MOLECULAR-CLONING AND NUCLEOTIDE-SEQUENCES OF CDNAS ENCODING SUBUNITS-I, SUBUNIT-II, AND SUBUNIT-IX OF EUGLENA-GRACILIS MITOCHONDRIAL COMPLEX-III

    JY CUI; K MUKAI; K SAEKI; H MATSUBARA

    cDNA clones encoding subunits I, II, and IX of Euglena gracilis mitochondrial complex III have been isolated from a lambdagt11 cDNA expression library by immunoscreening with an antiserum against the complex of the organism. Determination of the nucleotide sequences and amino-terminal amino acid sequences of purified subunits revealed that subunits II and IX, respectively, consist of 432 and 70 amino acids as their mature forms and possess potential presequences of 42 and 30 amino acids. The amino-terminal parts of the presequences had typical structural features of the mitochondrial targeting signal. Such features were also found at the amino-terminal region of the predicted subunit I protein, which comprises 494 residues. However, the amino terminus of the purified subunit I could not be detected, possibly because of a post-translational modification. Euglena subunits I and II both showed similarities to the members of the protein family which comprises complex III core proteins, mitochondrial processing peptidases (MPP) and processing enhancing proteins (PEP). Namely, the Euglena subunit I could be assigned to core 1 protein and the subunit II to core 2 protein in the family. In contrast, the subunit IX seemed to be peculiar to Euglena complex III. At 5'-untranslated regions, the three cloned cDNAs for subunits I, II, and IX had a common poly(T)CG structure which has also been reported for other Euglena cDNAs of nuclear genes., JAPANESE BIOCHEMICAL SOC, Jan. 1994, JOURNAL OF BIOCHEMISTRY, 115 (1), 98 - 107, web_of_science

    Scientific journal

  • NUCLEOTIDE-SEQUENCE AND GENETIC-ANALYSIS OF THE REGION ESSENTIAL FOR FUNCTIONAL EXPRESSION OF THE GENE FOR FERREDOXIN-I, FDXN, IN RHODOBACTER-CAPSULATUS - SHARING OF ONE UPSTREAM ACTIVATOR SEQUENCE IN OPPOSITE DIRECTIONS BY 2 OPERONS RELATED TO NITROGEN-FIXATION

    K SAEKI; K TOKUDA; T FUJIWARA; H MATSUBARA

    Nucleotide sequencing of the region upstream of two ferredoxin genes, fdxC and fdxN, of Rhodobacter capsulatus revealed the existence of one open reading frame (ORF), ORFU1, in the same orientation as these genes and two other ORFs, ORFU2 and ORFU3, in the opposite orientation. Two potential -24/-12 promoters were found in front of ORFU1 and ORFU2, respectively, and there was a putative upstream activator sequence (UAS) or NifA-binding site between them. The ORFs corresponded to no known nif genes. However, analysis of their putative products showed that the product of ORFU1 (M(r) 47,912) and that of ORFU3 (M(r) 19,090) had a flavodoxin-like domain and a 2[4Fe-4S] ferredoxin-like domain, respectively, and that the product of ORFU2 (M(r) 20,424) was a hydrophobic protein with six potential membrane-spanning portions. Results of interposon mutagenesis and complementation experiments indicated that ORFU2 but not ORFU1 is essential for nitrogen fixation and that additional gene(s) essential for nitrogen fixation must be present in the unsequenced region adjacent to ORFU3. Translational fusion analysis involving lacZYA and fdxN or ORFU3 provided evidence that the putative UAS is responsible for regulation of both ORFU1-fdxC-fdxN and ORFU2-ORFU3 operons in opposite orientations, and that the control of the latter is stricter than that of the former., JAPANESE SOC PLANT PHYSIOLOGISTS, Mar. 1993, PLANT AND CELL PHYSIOLOGY, 34 (2), 185 - 199, web_of_science

    Scientific journal

  • Structural and Functional Diversity of Ferredoxins and Related Proteins

    Hiroshi Matsubara; Kazuhiko Saeki

    Elsevier, 1992, Advances in Inorganic Chemistry, 38, 223 - 280, doi

    In book

  • GENETIC-ANALYSIS OF FUNCTIONAL DIFFERENCES AMONG DISTINCT FERREDOXINS IN RHODOBACTER-CAPSULATUS

    K SAEKI; Y SUETSUGU; K TOKUDA; Y MIYATAKE; DA YOUNG; BL MARRS; H MATSUBARA

    Rhodobacter capsulatus has been known to possess two ferredoxins (I and II) with distinct physicochemical and structural properties: ferredoxin I is a 2[4Fe-4S] type and the other is a [3Fe-4S][4Fe-4S] type. To analyze their possible functional differences, their genes (fdxN and fdxA) were cloned, sequenced, and subjected to interposon mutagenesis experiments. The former gene was adjacent to a gene encoding a chloroplast-type [2Fe-2S] ferredoxin (fdxC). Mutants with inactivated fdxN and/or fdxC were obtained, and they showed virtually no growth under nitrogen-fixing conditions. Complementation experiments confirmed that both fdxN and fdxC were required for nitrogen fixation. On the other hand, we have not been able to disrupt fdxA under the screening conditions surveyed, including conditions that do not require nitrogenase activity for growth, suggesting that ferredoxin II could have an unknown essential role(s). These indicate functional differences among multiple ferredoxins in one bacterium other than in cyanobacterial heterocysts and indispensability of certain ferredoxins in nitrogen fixation other than Rhizobium meliloti FdxN., AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, Jul. 1991, JOURNAL OF BIOLOGICAL CHEMISTRY, 266 (20), 12889 - 12895, web_of_science

    Scientific journal

  • FA/FB PROTEIN FROM THE SPINACH PHOTOSYSTEM-I COMPLEX - ISOLATION IN A NATIVE-STATE AND SOME PROPERTIES OF THE IRON-SULFUR CLUSTERS

    H OHOKA; S ITOH; K SAEKI; Y TAKAHASHI; H MATSUBARA

    The F(A)/F(B) protein of the photosystem I complex was isolated from spinach leaves in a native state by use of anaerobic systems. The protein contained 8.5 non-heme iron atoms and 8.0 acid-labile sulfur atoms per molecule, consistent with the current concept that it has two [4Fe-4S] clusters. Its absorption spectrum was very similar to those of bacterial-type ferredoxins. The ratio of the absorbance at 390 nm to that at 280 nm was 0.6, and the molar extinction coefficient at 390 nm was 32,000 M-1.cm-1. The oxidation-reduction properties of the iron-sulfur clusters were examined by redox potentiometry and EPR spectroscopy. The two clusters were distinguishable in terms of their oxidation-reduction midpoint potentials; their E(m) values were determined to be about -470 mV and -560 mV, respectively., JAPANESE SOC PLANT PHYSIOLOGISTS, Jan. 1991, PLANT AND CELL PHYSIOLOGY, 32 (1), 11 - 17, web_of_science

    Scientific journal

  • 2 DISTINCT FERREDOXINS FROM RHODOBACTER-CAPSULATUS - COMPLETE AMINO-ACID-SEQUENCES AND MOLECULAR EVOLUTION

    K SAEKI; Y SUETSUGU; Y YAO; T HORIO; BL MARRS; H MATSUBARA

    JAPAN BIOCHEMICAL SOC, Sep. 1990, JOURNAL OF BIOCHEMISTRY, 108 (3), 475 - 482, web_of_science

    Scientific journal

  • A PLANT-FERREDOXIN-LIKE GENE IS LOCATED UPSTREAM OF FERREDOXIN-I GENE (FDXN) OF RHODOBACTER-CAPSULATUS

    K SAEKI; Y MIYATAKE; DA YOUNG; BL MARRS; H MATSUBARA

    OXFORD UNIV PRESS UNITED KINGDOM, Feb. 1990, NUCLEIC ACIDS RESEARCH, 18 (4), 1060 - 1060, web_of_science

  • FERREDOXIN AND RUBREDOXIN FROM BUTYRIBACTERIUM-METHYLOTROPHICUM - COMPLETE PRIMARY STRUCTURES AND CONSTRUCTION OF PHYLOGENETIC TREES

    K SAEKI; Y YAO; S WAKABAYASHI; GJ SHEN; JG ZEIKUS; H MATSUBARA

    JAPANESE BIOCHEMICAL SOC, Oct. 1989, JOURNAL OF BIOCHEMISTRY, 106 (4), 656 - 662, web_of_science

    Scientific journal

  • PURIFICATION AND PROPERTIES OF FERREDOXIN AND RUBREDOXIN FROM BUTYRIBACTERIUM-METHYLOTROPHICUM

    K SAEKI; MK JAIN; GJ SHEN; RC PRINCE; JG ZEIKUS

    AMER SOC MICROBIOLOGY, Sep. 1989, JOURNAL OF BACTERIOLOGY, 171 (9), 4736 - 4741, web_of_science

    Scientific journal

  • PSEUDOMONAS-STUTZERI FERREDOXIN - CLOSE SIMILARITY TO AZOTOBACTER-VINELANDII AND PSEUDOMONAS-OVALIS FERREDOXINS

    K SAEKI; S WAKABAYASHI; WG ZUMFT; H MATSUBARA

    JAPANESE BIOCHEMICAL SOC, Aug. 1988, JOURNAL OF BIOCHEMISTRY, 104 (2), 242 - 246, web_of_science

    Scientific journal

  • THE PROTEIN RESPONSIBLE FOR CENTER A/B IN SPINACH PHOTOSYSTEM-I - ISOLATION WITH IRON-SULFUR CLUSTER(S) AND COMPLETE SEQUENCE-ANALYSIS

    H OHOKA; Y TAKAHASHI; K KURIYAMA; K SAEKI; H MATSUBARA

    JAPANESE BIOCHEMICAL SOC, Jun. 1988, JOURNAL OF BIOCHEMISTRY, 103 (6), 962 - 968, web_of_science

    Scientific journal

  • PRELIMINARY CRYSTALLOGRAPHIC STUDY OF A RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE-OXYGENASE FROM CHROMATIUM-VINOSUM

    H NAKAGAWA; M SUGIMOTO; Y KAI; S HARADA; K MIKI; N KASAI; K SAEKI; T KAKUNO; T HORIO

    ACADEMIC PRESS LTD, Oct. 1986, JOURNAL OF MOLECULAR BIOLOGY, 191 (3), 577 - 578, web_of_science

  • BARLEY LEAF PEROXIDASE - PURIFICATION AND CHARACTERIZATION

    K SAEKI; O ISHIKAWA; T FUKUOKA; H NAKAGAWA; Y KAI; T KAKUNO; J YAMASHITA; N KASAI; T HORIO

    JAPANESE BIOCHEMICAL SOC, Feb. 1986, JOURNAL OF BIOCHEMISTRY, 99 (2), 485 - 494, web_of_science

    Scientific journal

  • A NOVEL FAD-PROTEIN THAT ALLOWS EFFECTIVE REDUCTION OF METHYL VIOLOGEN BY NADH (NADH-METHYL VIOLOGEN REDUCTASE) FROM PHOTOSYNTHETIC BACTERIUM, RHODOSPIRILLUM-RUBRUM - PURIFICATION AND CHARACTERIZATION

    K SAEKI; T HARUNA; T KAKUNO; J YAMASHITA; T HORIO

    JAPANESE BIOCHEMICAL SOC, Feb. 1986, JOURNAL OF BIOCHEMISTRY, 99 (2), 423 - 435, web_of_science

    Scientific journal

  • COG分類を考慮した遺伝子発現プロファイルデータのクラスタリング手法

    大古田,みのり; 石川,由羽; 高田,雅美; 佐伯,和彦; 城,和貴

    Jun. 2015, (23)

  • Genome Sequence and Gene Functions in Mesorhizobium loti and Relatives

    Kazuhiko Saeki

    27 Sep. 2014, Compendium of Plant Genomes, doi

MISC

  • A MATE-type transporter responsible for iron supply to nodule infection zone of Lotus japonicus.

    高梨功次郎; 横正健剛; 高橋宏和; 佐伯和彦; 杉山暁史; 佐藤修正; 田畑哲之; 中園幹生; 馬建鋒; 矢崎一史

    2012, 第15回国際分子・植物・微生物相互作用学会(IS-MPMI) 2012.7.29-2012.8.2

    Summary international conference

  • Symbiotic significance of type III secretion system in Mesorhizobium loti

    Saori Okabe; Shin Okazaki; Kouhei Tejima; Michael Gottfert; Kazuhiko Saeki

    OXFORD UNIV PRESS, 2007, PLANT AND CELL PHYSIOLOGY, 48, S47 - S47, web_of_science

    Summary international conference

  • ミヤコグサで解き明かす菌根・根粒共生系の分子基盤

    SAEKI Kazuhiko

    Sep. 2006, 蛋白質・核酸・酵素, 51 (9), 1044-1050

  • 根粒菌からみた共生システム

    南澤 究; 佐伯和彦; 佐藤修正; 下田宜司

    2006, 蛋白質・核酸・酵素, 51

    Introduction scientific journal

  • Characterization of a novel Lotus japonicus symbiotic mutant, Lot1, that shows reduced nodule numberand distorted trichomes

    Y Ooki; M Banba; K Yano; J Maruya; S Sato; S Tabata; K Saeki; M Hayashi; M Kawaguchi; K Izui; S Hata

    SPRINGER, 2005, Biological Nitrogen Fixation, Sustainable Agriculture and the Environment, 41, 233 - 233, web_of_science

    Summary international conference

  • 共生窒素固定研究の最新情報(10):根粒菌研究のためのリソース

    SAEKI Kazuhiko

    Apr. 2003, 農業技術, 58 (4), 183-188

  • Analysis of gene expression of mesorhizobium loti by genomic macro-array

    T Ohwada; K Minamisawa; P Dawady; H Mitsui; M Itakura; T Kaneko; S Tabata; T Yokoyama; K Tejima; K Saeki; H Ohmori; Y Murooka; M Hayashi; S Tajima; M Nomura; K Shimomura; M Abe; A Suzuki; Y Shimoda; T Uchiumi

    OXFORD UNIV PRESS, 2003, PLANT AND CELL PHYSIOLOGY, 44, S210 - S210, web_of_science

    Summary international conference

  • B-06 炭素飢餓条件下におけるミヤコグサ根粒菌の網羅的な遺伝子発現解析(生理・増殖2,口頭発表)

    板倉 学; 大和田 琢二; 折笠 善丈; 南澤 究; 三井 久幸; 金子 貴一; 田畑 哲之; 横山 正; 手島 光平; 佐伯 和彦; 室岡 義勝; 林 誠; 田島 茂行; 野村 美加; 下村 憲司朗; 阿部 美紀子; 鈴木 章弘; 下田 宜司; 内海 俊樹

    日本微生物生態学会, 15 Nov. 2002, 日本微生物生態学会講演要旨集, (18), cinii_articles

  • 6-21 全ゲノム塩基配列情報に基づくミヤコグサ根粒菌の網羅的遺伝子発現解析(6.土壌生物)

    大和田 琢二; 折笠 善丈; 南澤 究; 三井 久幸; 板倉 学; 田畑 哲之; 金子 貴一; 横山 正; 手島 光平; 佐伯 和彦; 大森 博文; 室岡 義勝; 林 誠; 田島 茂行; 野村 美加; 下村 憲司朗; 阿部 美紀子; 内海 俊樹; 鈴木 章弘; 下田 宜司

    一般社団法人日本土壌肥料学会, 25 Mar. 2002, 日本土壌肥料学会講演要旨集, (48), cinii_articles

  • Genetic analysis of the Mesorhizobium loti mutant exo-22 that has defects in exopolysaccharide synthesis and symbiotic nitrogen fixation.

    E Mishima; H Imaizumi-Anraku; M Kawaguchi; K Saeki

    OXFORD UNIV PRESS, 2002, PLANT AND CELL PHYSIOLOGY, 43, S72 - S72, web_of_science

    Summary international conference

  • 光合成細菌の多様なフェレドキシン

    SAEKI Kazuhiko

    Nov. 1993, 化学と生物, 31 (11), 750-754

  • EVOLUTIONARY ASPECTS OF IRON-SULFUR PROTEINS IN PHOTOSYNTHETIC APPARATUS

    Y FUJITA; Y TAKAHASHI; H OHOKA; K SAEKI; K FUKUYAMA; H MATSUBARA

    KLUWER ACADEMIC PUBL, Oct. 1992, PHOTOSYNTHESIS RESEARCH, 34 (1), 96 - 96, web_of_science

    Summary international conference

  • STRUCTURAL AND FUNCTIONAL DIVERSITY OF FERREDOXINS AND RELATED PROTEINS

    H MATSUBARA; K SAEKI

    ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS, 1992, ADVANCES IN INORGANIC CHEMISTRY, 38, 223 - 280, web_of_science

    Book review

  • TRANSCRIPTIONAL ANALYSIS OF 2 RHODOBACTER-CAPSULATUS FERREDOXINS BY TRANSLATIONAL FUSION TO ESCHERICHIA-COLI-LACZ

    Y SUETSUGU; K SAEKI; H MATSUBARA

    Plasmids which contained the translational fusion of Escherichia coli lacZ to Rhodobacter capsulatus ferredoxin genes, fdxN and fdxA, were constructed. Effects of growth conditions on the expression of each ferredoxin were analyzed by measuring the beta-galactosidase activity in R. capsulatus which harbored a corresponding plasmid. Transcription of fdxN::lacZ, the ferredoxin I fusion gene, was regulated at least 100-fold by either NH4+ or O2 but not by illumination, confirming that fdxN belongs to the nif-gene family. Transcription of fdxA::lacZ, the ferredoxin II fusion gene, however, was constant under all the conditions surveyed, suggesting that the protein has some constitutive function(s)., ELSEVIER SCIENCE BV, Nov. 1991, FEBS LETTERS, 292 (1-2), 13 - 16, web_of_science

  • 古細菌のフェレドキシン

    SAEKI Kazuhiko

    Apr. 1990, Cell Science, 6 (4), 293-296

  • A PROTEIN CARRYING FE-S CENTER A/B IN SPINACH CHLOROPLAST PHOTOSYSTEM-I (PSI)

    H MATSUBARA; H OHOKA; Y TAKAHASHI; K SAEKI

    FEDERATION AMER SOC EXP BIOL, Mar. 1988, FASEB JOURNAL, 2 (4), A768 - A768, web_of_science

    Summary international conference

  • REGULATORY METABOLISM OF SINGLE CARBON-COMPOUNDS BY BUTYRIBACTERIUM-METHYLOTROPHICUM

    MK JAIN; GJ SHEN; K SAEKI; JG ZEIKUS

    AMER CHEMICAL SOC, Aug. 1987, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 194, 34 - MBTD, web_of_science

    Summary international conference

Books etc

  • “Chapter 5: Genome sequence and gene functions in Mesorhizobium loti and relatives” In The Lotus japonicus Genome (Eds. Tabata S and Stougaard J)

    SAEKI Kazuhiko (, Range: 分担)

    Springer-Verlag, Berlin, Germany, Oct. 2014, 41-57 (ISBN: 9783662442692)

  • 光合成微生物の機能と応用

    SAEKI Kazuhiko (, Range: 分担)

    シーエムシー出版, Dec. 2006, 170-176

  • モデル植物の実験プロトコール(第3版)イネ・シロイヌナズナ・ミヤコグサ編

    SAEKI Kazuhiko (, Range: 分担)

    秀潤社, Apr. 2005, 315-317

  • “Electron Transport to Nitrogenase: Diverse Routes for A Common Destination” In Genetics and Regulation of Nitrogen Fixing in Free-Living Bacteria (Eds. W. Klipp, B. Masepohl, J.R. Gallon & W.E. Newton) pp.257-290

    SAEKI Kazuhiko (, Range: 筆頭著者)

    Kluwer Academic Publishers, Dortrecht, Netherland (ISBN: 1-4020-2178-X), 2004

  • “Genome analysis of Mesorhizobium loti” In Biotechnology in Agriculture and Forestry Vol 52. Brassica and Legumes: From genome structure to plant breeding (Eds. T. Nagata and S. Tabata) pp.203-216

    SAEKI Kazuhiko (, Range: 分担)

    Springer-Verlag, Berlin, Germany (ISBN: 3-540-42728-7), 2003

  • “Electron Transport Pathway to Nitrogenase in Rhodobacter capsulatus : Rnf Complex and Its Relatives in Non-Diazotrophs” in Achievements and Objectives in Nitrogen Fixation beyond Horizon (F. Pedorosa, A. Kondorosi & G. Walker eds.)

    SAEKI Kazuhiko (, Range: 筆頭著者)

    Kluwer Academic Publishers, Dortrecht, Netherland (ISBN: 0-7923-6233-0), Mar. 2000

  • 蛋白質・酵素の基礎実験法 改訂第2版

    SAEKI Kazuhiko (, Range: 分担)

    南江堂, Nov. 1994, 232-241, 355-361 (ISBN: 9784524401239)

Presentations

  • 根粒菌菌体外分泌系による窒素固定共生の制御

    SAEKI Kazuhiko

    第26回植物細菌病談話会, Oct. 2014, 岡山空港温泉 レスパール藤ケ鳴

  • GFP派生物導入変異体を用いた共生成立過程における根粒菌体pHの測定にむけて

    SAEKI Kazuhiko

    第55回日本植物生理学会年会, Mar. 2014, 富山大学・五福キャンパス

  • Core gene sets and evolution of symbiosis islands in rhizobial isolates from Lotus japonicas indigenous to Japan

    SAEKI Kazuhiko; Kazuhiko Saeki; Hiroko Kasai-Maita; Kazuna Kubota; Takakazu Kaneko; Hideki Hirakawa; Satoshi Tabata; Shusei Sato

    18th International Congress on Nitrogen Fixation, Oct. 2013, Phoenix Seagaia Resort; World Convention Center Summit, Miyazaki, Japan

  • 根粒菌エフェクターによるマメ科植物との共生成立の制御

    SAEKI Kazuhiko

    第54回日本植物生理学会年会・シンポジウム10・微生物エフェクター:植物と微生物の攻防と調和の鍵を握る分子, Mar. 2013, 岡山大学・津島キャンパス

  • β-カロテンを蓄積するゲノム改変光合成細菌株を用いたレチナール大量合成条件の探索

    清水香織; 高市真一; 佐伯和彦

    第93回日本生化学会大会, Sep. 2020, 14 Sep. 2020, 16 Sep. 2020

  • β-カロテン生産改良株を用いたレチナール合成の試み

    清水香織; 高市真一; 佐伯和彦

    第61回日本植物生理学会年会, Mar. 2020, 19 Mar. 2020, 21 Mar. 2020

  • Rhodobacter capsulatus におけるレチナール合成の試み

    清水香織; 高市真一; 佐伯和彦

    第92回日本生化学会大会, 19 Sep. 2019, 18 Sep. 2019, 20 Sep. 2019

  • ミヤコグサ根粒菌カタラーゼKatEはプロトヘムとヘムdをもつ

    三浦帆波; 西川佳那; 本田裕樹; 藤井浩; 佐伯和彦

    第92回日本生化学会大会, 18 Sep. 2019, 18 Sep. 2019, 20 Sep. 2019

  • ミヤコグサ根粒菌5-アミノレブリン酸合成酵素は大腸菌内での根粒菌カタラーゼのホロ酵素発現を補助するか?

    三浦帆波; 佐伯和彦

    第91回日本生化学会大会(京都国際会館), 24 Sep. 2018, 24 Sep. 2018, 26 Sep. 2018

  • Bradyrhizobium elkanii USDA61 株の3型分泌エフェクターはミヤコグサに複数の防御反応を誘導する

    日下部 翔平; 金子 貴一; 安田 美智子; 三輪 大樹; 岡崎 伸; 佐伯 和彦; 佐藤 修正

    植物微生物研究会・第28回研究交流会(鳥取大学農学部), Sep. 2018, 19 Sep. 2018, 21 Sep. 2018

  • 大腸菌を宿主とするミヤコグサ根粒菌のカタラーゼと5-アミノレブリン酸合成酵素の共発現

    三浦 帆波; 白井 理恵; 浅野 美和; 藤井 浩; 佐伯 和彦

    植物微生物研究会・第28回研究交流会(鳥取大学農学部), Sep. 2018, 19 Sep. 2018, 21 Sep. 2018

  • 宮古島の土壌とミヤコグサから単離された根粒菌の多様性調査

    疋田 真穂; 佐伯 和彦

    植物微生物研究会・第28回研究交流会(鳥取大学農学部), Sep. 2018, 18 Sep. 2018, 21 Sep. 2018

  • 光合成細菌のクロマトフォア上での動物光受容体の発現に向けて

    清水香織; 高市真一; 佐伯和彦

    第59回日本植物生理学会(札幌コンベンションセンター), Mar. 2018, 28 Mar. 2018, 30 Mar. 2018

Association Memberships

  • Japanese Society for Plant Physiologists

  • The Japanese Biochemical Society

  • American Society for Microbiology

  • 植物微生物研究会

  • International Society for Molecular-Plant Microbe Interaction

  • 日本ゲノム微生物学会

Works

  • 科学技術総合研究委託費・委託業務・平成19年度「科学技術連携施策群の効果的・効率的な推進 食料・生物生産研究」、 「植物・微生物間共生におけるゲノム相互作用」のうち、「3-2.宿主防御システムに対抗し回避・抑制するための根粒菌マシナリー」

    Sep. 2007, Mar. - 2010



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