研究者詳細 - 根本　理子

論文 - 根本　理子

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Molecular evolution of gas cavity in [NiFeSe] hydrogenases resurrected in silico. 査読国際誌

Takashi Tamura, Naoki Tsunekawa, Michiko Nemoto, Kenji Inagaki, Toshiyuki Hirano, Fumitoshi Sato

Scientific reports 6 19742 - 19742 2016年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATURE PUBLISHING GROUP

Oxygen tolerance of selenium-containing [NiFeSe] hydrogenases (Hases) is attributable to the high reducing power of the selenocysteine residue, which sustains the bimetallic Ni-Fe catalytic center in the large subunit. Genes encoding [NiFeSe] Hases are inherited by few sulphate-reducing δ-proteobacteria globally distributed under various anoxic conditions. Ancestral sequences of [NiFeSe] Hases were elucidated and their three-dimensional structures were recreated in silico using homology modelling and molecular dynamic simulation, which suggested that deep gas channels gradually developed in [NiFeSe] Hases under absolute anaerobic conditions, whereas the enzyme remained as a sealed edifice under environmental conditions of a higher oxygen exposure risk. The development of a gas cavity appears to be driven by non-synonymous mutations, which cause subtle conformational changes locally and distantly, even including highly conserved sequence regions.

DOI： 10.1038/srep19742

Structural Insights into HIV-1 Vif-APOBEC3F Interaction. 査読国際誌

Masaaki Nakashima, Hirotaka Ode, Takashi Kawamura, Shingo Kitamura, Yuriko Naganawa, Hiroaki Awazu, Shinya Tsuzuki, Kazuhiro Matsuoka, Michiko Nemoto, Atsuko Hachiya, Wataru Sugiura, Yoshiyuki Yokomaku, Nobuhisa Watanabe, Yasumasa Iwatani

Journal of virology 90 ( 2 ) 1034 - 47 2016年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC MICROBIOLOGY

UNLABELLED: The HIV-1 Vif protein inactivates the cellular antiviral cytidine deaminase APOBEC3F (A3F) in virus-infected cells by specifically targeting it for proteasomal degradation. Several studies identified Vif sequence motifs involved in A3F interaction, whereas a Vif-binding A3F interface was proposed based on our analysis of highly similar APOBEC3C (A3C). However, the structural mechanism of specific Vif-A3F recognition is still poorly understood. Here we report structural features of interaction interfaces for both HIV-1 Vif and A3F molecules. Alanine-scanning analysis of Vif revealed that six residues located within the conserved Vif F1-, F2-, and F3-box motifs are essential for both A3C and A3F degradation, and an additional four residues are uniquely required for A3F degradation. Modeling of the Vif structure on an HIV-1 Vif crystal structure revealed that three discontinuous flexible loops of Vif F1-, F2-, and F3-box motifs sterically cluster to form a flexible A3F interaction interface, which represents hydrophobic and positively charged surfaces. We found that the basic Vif interface patch (R17, E171, and R173) involved in the interactions with A3C and A3F differs. Furthermore, our crystal structure determination and extensive mutational analysis of the A3F C-terminal domain demonstrated that the A3F interface includes a unique acidic stretch (L291, A292, R293, and E324) crucial for Vif interaction, suggesting additional electrostatic complementarity to the Vif interface compared with the A3C interface. Taken together, these findings provide structural insights into the A3F-Vif interaction mechanism, which will provide an important basis for development of novel anti-HIV-1 drugs using cellular cytidine deaminases. IMPORTANCE: HIV-1 Vif targets cellular antiviral APOBEC3F (A3F) enzyme for degradation. However, the details on the structural mechanism for specific A3F recognition remain unclear. This study reports structural features of interaction interfaces for both HIV-1 Vif and A3F molecules. Three discontinuous sequence motifs of Vif, F1, F2, and F3 boxes, assemble to form an A3F interaction interface. In addition, we determined a crystal structure of the wild-type A3F C-terminal domain responsible for the Vif interaction. These results demonstrated that both electrostatic and hydrophobic interactions are the key force driving Vif-A3F binding and that the Vif-A3F interfaces are larger than the Vif-A3C interfaces. These findings will allow us to determine the configurations of the Vif-A3F complex and to construct a structural model of the complex, which will provide an important basis for inhibitor development.

DOI： 10.1128/JVI.02369-15

Identification and characterization of the zosA gene involved in copper uptake in Bacillus subtilis 168. 査読国際誌

Takahiro Fukuhara, Kazuo Kobayashi, Yousuke Kanayama, Shu-ichi Enomoto, Taeko Kondo, Naoki Tsunekawa, Michiko Nemoto, Naotake Ogasawara, Kenji Inagaki, Takashi Tamura

Bioscience, biotechnology, and biochemistry 80 ( 3 ) 600 - 9 2016年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：TAYLOR & FRANCIS LTD

DL-Penicillamine, a copper-specific metal chelator, remarkably suppressed the growth of Bacillus subtilis 168 when added to a synthetic medium under Cu(2+) limitation. DNA microarray and screening of 2,602 knockout mutants showed that the zosA gene was de-repressed in the presence of 0.1% dl-penicillamine, and that the zosA mutant was sensitive to dl-penicillamine medium. The zosA mutant delayed the growth under Cu-limitation even without the chelator, and the sensitivity to dl-penicillamine was reversed by induction using 0.3 mM IPTG and the Pspac promoter inserted directly upstream of the zosA gene. Furthermore, the zosA mutant showed elevated tolerance of excessive Cu(2+) but not of excessive Zn(2+) added to LB and synthetic media. Homology modeling of the ZosA protein suggested that the protein can fold itself into essential domains for constituting a metal transporting ATPase. Our study suggests that zosA is a candidate gene involved in copper uptake.

DOI： 10.1080/09168451.2015.1107462

Draft Genome Sequence of Streptomyces incarnatus NRRL8089, which Produces the Nucleoside Antibiotic Sinefungin. 査読国際誌

Kenshiro Oshima, Masahira Hattori, Hitomi Shimizu, Koji Fukuda, Michiko Nemoto, Kenji Inagaki, Takashi Tamura

Genome announcements 3 ( 4 ) 2015年7月

記述言語：英語掲載種別：研究論文（学術雑誌）

A draft genome sequence of Streptomyces incarnatus NRRL8089, which produces the nucleoside antibiotic sinefungin, is described here. The genome contains 8,897,465 bp in 76 contigs and 8,266 predicted genes. Interestingly, the genome encodes an open reading frame for selenocysteine-containing formate dehydrogenase-O and the selenoprotein biosynthetic gene cluster selABCD.

DOI： 10.1128/genomeA.00715-15

Oil accumulation by the oleaginous diatom Fistulifera solaris as revealed by the genome and transcriptome. 査読国際誌

Tsuyoshi Tanaka, Yoshiaki Maeda, Alaguraj Veluchamy, Michihiro Tanaka, Heni Abida, Eric Maréchal, Chris Bowler, Masaki Muto, Yoshihiko Sunaga, Masayoshi Tanaka, Tomoko Yoshino, Takeaki Taniguchi, Yorikane Fukuda, Michiko Nemoto, Mitsufumi Matsumoto, Pui Shan Wong, Sachiyo Aburatani, Wataru Fujibuchi

The Plant cell 27 ( 1 ) 162 - 76 2015年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC PLANT BIOLOGISTS

Oleaginous photosynthetic organisms such as microalgae are promising sources for biofuel production through the generation of carbon-neutral sustainable energy. However, the metabolic mechanisms driving high-rate lipid production in these oleaginous organisms remain unclear, thus impeding efforts to improve productivity through genetic modifications. We analyzed the genome and transcriptome of the oleaginous diatom Fistulifera solaris JPCC DA0580. Next-generation sequencing technology provided evidence of an allodiploid genome structure, suggesting unorthodox molecular evolutionary and genetic regulatory systems for reinforcing metabolic efficiencies. Although major metabolic pathways were shared with nonoleaginous diatoms, transcriptome analysis revealed unique expression patterns, such as concomitant upregulation of fatty acid/triacylglycerol biosynthesis and fatty acid degradation (β-oxidation) in concert with ATP production. This peculiar pattern of gene expression may account for the simultaneous growth and oil accumulation phenotype and may inspire novel biofuel production technology based on this oleaginous microalga.

DOI： 10.1105/tpc.114.135194

Morphological and molecular phylogenetic analysis of the high triglyceride-producing marine diatom, Fistulifera solaris sp nov (Bacillariophyceae) 査読

Mitsufumi Matsumoto, Shigeki Mayama, Michiko Nemoto, Yorikane Fukuda, Masaki Muto, Tomoko Yoshino, Tadashi Matsunaga, Tsuyoshi Tanaka

PHYCOLOGICAL RESEARCH 62 ( 4 ) 257 - 268 2014年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL

Fistulifera sp. strain JPCC DA0580, a marine pennate diatom, contains extremely high levels of intracellular triglyceride and has been suggested as a promising source of feedstock for biodiesel fuels. JPCC DA0580 was isolated from a mangrove swamp located in Sumiyo Bay below the mouths of the Sumiyo and Yakugachi Rivers in Amami-Ohshima, Kagoshima, Japan. In this study, the morphology and the 18S rDNA sequence of JPCC DA0580 were compared with those of other Fistulifera strains. JPCC DA0580 possesses morphological characters of the genus Fistulifera, namely lightly silicified frustules, a distinct median costa (raphe sternum), and a wart-like central pore (fistula). Morphometric analysis revealed that JPCC DA0580 differs from other Fistulifera species by the presence of a valve with coarser striation and coarser areolation. On the basis of 18S rDNA phylogeny, JPCC DA0580 formed a well-supported clade with other members of the Fistulifera species complex, although the number of nucleotide substitutions was highest in JPCC DA0580. Our results led us to propose the taxonomic name Fistulifera solaris sp. nov. for JPCC DA0580.

DOI： 10.1111/pre.12066

Identification of a frustule-associated protein of the marine pennate diatom Fistulifera sp. strain JPCC DA0580. 査読国際誌

Michiko Nemoto, Yoshiaki Maeda, Masaki Muto, Masayoshi Tanaka, Tomoko Yoshino, Shigeki Mayama, Tsuyoshi Tanaka

Marine genomics 16 39 - 44 2014年8月

記述言語：英語掲載種別：研究論文（学術雑誌）

Among the proteins localized on the cell wall (frustule) of diatoms (frustule-associated proteins), several proteins tightly associated with the cell wall have been implicated in frustule formation. These proteins include diatom-specific unique serine- and lysine-rich sequences represented by silaffins. Taking advantage of available genome information, we used a recently described bioinformatics approach to screen silaffin-like proteins rich in serine and lysine from the genome of the marine pennate diatom Fistulifera sp. strain JPCC DA0580 and identified 7 proteins. All of the proteins shared a sequence motif called the XGXG domain, which was also confirmed in a silaffin-like protein identified in other diatoms. In vivo localization analysis revealed that one of the identified proteins, G7408, occurs throughout the frustule with a slightly uneven distribution. This novel frustule-associated protein could be a useful tool to elucidate the mechanism of biosilica formation in diatoms and to functionalize this strain for future biotechnological applications.

DOI： 10.1016/j.margen.2014.01.006

2030年への挑戦"藻類を燃料に

田中剛, 根本理子, 吉野知子

太陽エネルギー 39 27 - 35 2014年1月

Proteomics analysis of oil body-associated proteins in the oleaginous diatom. 査読国際誌

Daisuke Nojima, Tomoko Yoshino, Yoshiaki Maeda, Masayoshi Tanaka, Michiko Nemoto, Tsuyoshi Tanaka

Journal of proteome research 12 ( 11 ) 5293 - 301 2013年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

For biodiesel production from microalgae, it is desirable to understand the entire triacylglycerol (TAG) metabolism. TAG accumulation occurs in oil bodies, and although oil body-associated proteins could play important roles in TAG metabolism, only a few microalgal species have been studied by a comprehensive analysis. Diatoms are microalgae that are promising producers of biodiesel, on which such proteomics analysis has not been conducted to date. Herein, we identified oil body-associated proteins in the oleaginous diatom Fistulifera sp. strain JPCC DA0580. The oil body fraction was separated by cell disruption with beads beating and subsequent ultracentrifugation. Contaminating factors could be removed by comparing proteins from the oil body and the soluble fractions. This novel strategy successfully revealed 15 proteins as oil body-associated protein candidates. Among them, two proteins, which were parts of proteins predicted to have transmembrane domains, were indeed confirmed to specifically localize to the oil bodies in this strain by observation of GFP fusion proteins. One (predicted to be a potassium channel) was also detected from the ER, suggesting that oil bodies might originate from the ER. By utilizing this novel subtraction method, we succeeded in identifying the oil body-associated proteins in the diatom for the first time.

DOI： 10.1021/pr4004085

A process design and productivity evaluation for oil production by indoor mass cultivation of a marine diatom, Fistulifera sp. JPCC DA0580. 査読国際誌

Akira Satoh, Kyonosuke Ichii, Mitsufumi Matsumoto, Chihiro Kubota, Michiko Nemoto, Masayoshi Tanaka, Tomoko Yoshino, Tadashi Matsunaga, Tsuyoshi Tanaka

Bioresource technology 137 132 - 8 2013年6月

記述言語：英語掲載種別：研究論文（学術雑誌）

The present study involved the designing of a culture process and the evaluation of productivity of oil products from a highly oleaginous marine diatom, Fistulifera sp. JPCC DA0580, which had been cultured in a commercial-scale factory. The culture facility had a capacity of 48,000 L and held 96 flat-type 500-L photobioreactors (PBRs) equipped with artificial light, which secures a stable, perennial supply of the products. A 10 days culture that had reached a cell density of 6.5 g dry weight L(-1) possessing a cellular oil content of 48% (wt/wt) was found to provide the highest oil yield. On considering a production area of 1500 m(2), annual algal mass and oil productivity is 68.7 and 33.3 t ha(-1) year(-1), respectively. This study thus provides a reproducible prediction of a theoretical maximum oil yield from a highly oleaginous microalgal strain based on industrially practical production area.

DOI： 10.1016/j.biortech.2013.03.087

Phase Transformations and Structural Developments in the Radular Teeth of Cryptochiton Stelleri 査読

Qianqian Wang, Michiko Nemoto, Dongsheng Li, James C. Weaver, Brian Weden, John Stegemeier, Krassimir N. Bozhilov, Leslie R. Wood, Garrett W. Milliron, Christopher S. Kim, Elaine DiMasi, David Kisailus

ADVANCED FUNCTIONAL MATERIALS 23 ( 23 ) 2908 - 2917 2013年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-V C H VERLAG GMBH

During mineralization, the hard outer magnetite-containing shell of the radular teeth of Cryptochiton stelleri undergoes four distinct stages of structural and phase transformations: (i) the formation of a crystalline -chitin organic matrix that forms the structural framework of the non-mineralized teeth, (ii) the templated synthesis of ferrihydrite crystal aggregates along these organic fibers, (iii) subsequent solid state phase transformation from ferrihydrite to magnetite, and (iv) progressive magnetite crystal growth to form continuous parallel rods within the mature teeth. The underlying -chitin organic matrix appears to influence magnetite crystal aggregate density and the diameter and curvature of the resulting rods, both of which likely play critical roles in determining the local mechanical properties of the mature radular teeth.

DOI： 10.1002/adfm.201202894

Molecular Bioengineering of Magnetosomes for Biotechnological Applications 査読

Atsushi Arakaki, Michiko Nemoto, Tadashi Matsunaga

Coordination Chemistry in Protein Cages: Principles, Design, and Applications 241 - 271 2013年4月

記述言語：英語掲載種別：論文集(書籍)内論文出版者・発行元：John Wiley and Sons

Organisms produce inorganic/organic composite materials, called biominerals, show amazing structures and exhibit excellent physical/chemical properties that often outperform artificial materials. From the basic studies on magnetotactic bacteria and their magnetosome formation mechanisms, methods for functional design of magnetosomes and magnetotactic bacterial cells were established through molecular bioengineering. This chapter introduces recent progress on the basic studies of magnetosome formation mechanism and the design of functional magnetic particles and their applications to biotechnology based on their unique properties. Moreover, the results obtained from these fundamental studies allow us to develop novel molecular constructs on the magnetosome surface. The constructed functional magnetosomes generated by the molecular bioengineering techniques are used for various biotechnological applications. © 2013 John Wiley &amp
Sons, Inc. All rights reserved.

DOI： 10.1002/9781118571811.ch10

Establishment of a genetic transformation system for the marine pennate diatom Fistulifera sp. strain JPCC DA0580--a high triglyceride producer. 査読国際誌

Masaki Muto, Yorikane Fukuda, Michiko Nemoto, Tomoko Yoshino, Tadashi Matsunaga, Tsuyoshi Tanaka

Marine biotechnology (New York, N.Y.) 15 ( 1 ) 48 - 55 2013年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

A genetic transformation system for the marine pennate diatom, Fistulifera sp. JPCC DA0580, was established using microparticle bombardment methods. Strain JPCC DA0580 has been recently identified as the highest triglyceride (60 % w/w) producer from a culture collection of 1,393 strains of marine microalgae, and it is expected to be a feasible source of biodiesel fuel. The transformation conditions for strain JPCC DA0580 were optimised using the green fluorescent protein gene (gfp) and the gene encoding neomycin phosphotransferase II (nptII). The most efficient rate of transformation was attained when tungsten particles (0.6 μm in diameter) were used for microparticle bombardment. The effect of endogenous and exogenous promoters on the expression of nptII was examined. Endogenous promoters were more efficient for obtaining transformants compared with exogenous promoters. Southern hybridisation analysis suggested that nptII integrated into the nuclear genome. This genetic manipulation technique should allow us to understand the mechanisms of high triglyceride accumulation in this strain, thereby contributing to improving BDF production.

DOI： 10.1007/s10126-012-9457-0

Proteomic analysis from the mineralized radular teeth of the giant Pacific chiton, Cryptochiton stelleri (Mollusca). 査読国際誌

Michiko Nemoto, Qianqian Wang, Dongsheng Li, Songqin Pan, Tadashi Matsunaga, David Kisailus

Proteomics 12 ( 18 ) 2890 - 4 2012年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL

The biomineralized radular teeth of chitons are known to consist of iron-based magnetic crystals, associated with the maximum hardness and stiffness of any biomineral. Based on our transmission electron microscopy analysis of partially mineralized teeth, we suggest that the organic matrix within the teeth controls the iron oxide nucleation. Thus, we used Nano-LC-MS to perform a proteomic analysis of the organic matrix in radular teeth of the chiton Cryptochiton stelleri in order to identify the proteins involved in the biomineralization process. Since the genome sequence of C. stelleri is not available, cross-species similarity searching and de novo peptide sequencing were used to screen the proteins. Our results indicate that several proteins were dominant in the mineralized part of the radular teeth, amongst which, myoglobin and a highly acidic peptide were identified as possibly involved in the biomineralization process.

DOI： 10.1002/pmic.201100473

Assessment of the anti-biofouling potentials of a copper iodide-doped nylon mesh. 査読国際誌

Tetsuya Sato, Yoshie Fujimori, Tsuruo Nakayama, Yasuo Gotoh, Yoshihiko Sunaga, Michiko Nemoto, Tadashi Matsunaga, Tsuyoshi Tanaka

Applied microbiology and biotechnology 95 ( 4 ) 1043 - 50 2012年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SPRINGER

We propose a copper iodide (CuI)-doped nylon mesh prepared using polyiodide ions as a precursor toward anti-biofouling polymer textile. The CuI-doped nylon mesh was subjected to the prevention of biofouling in marine environments. The attachment of the marine organisms was markedly inhibited on the CuI-doped nylon mesh surface until 249 days. Scanning electron microscopy-energy dispersive X-ray analysis indicated that copper compounds were maintained in the nylon mesh after the field experiment, although copper content in the nylon mesh was reduced. Therefore, the copper ions slowly dissolved from nylon mesh will contribute to the long-term prevention of biofouling. Furthermore, electron spin resonance analysis revealed the generation of reactive oxygen species (ROS) from CuI-doped nylon mesh after the field experiment. One of the possibilities for toxic action of copper ions will be the direct effect of Cu+ -induced ROS on biofilm forming on nylon mesh surface. The proposed polymer textile can be applied to fishing and aquafarming nets, mooring rope for ship, or silt fence to restrict polluted water in marine environments.

DOI： 10.1007/s00253-011-3720-6

Investigation of the antiviral properties of copper iodide nanoparticles against feline calicivirus. 査読

Nozomi Shionoiri, Tetsuya Sato, Yoshie Fujimori, Tsuruo Nakayama, Michiko Nemoto, Tadashi Matsunaga, Tsuyoshi Tanaka

Journal of bioscience and bioengineering 113 ( 5 ) 580 - 6 2012年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：SOC BIOSCIENCE BIOENGINEERING JAPAN

This study demonstrated the antiviral properties of copper iodide (CuI) nanoparticles against the non-enveloped virus feline calicivirus (FCV) as a surrogate for human norovirus. The effect of CuI nanoparticles on FCV infectivity to Crandell-Rees feline kidney (CRFK) cells was elucidated. The infectivity of FCV to CRFK cells was greatly reduced by 7 orders of magnitude at 1000μgml(-1) CuI nanoparticles. At the conditions, electron spin resonance (ESR) analysis proved hydroxyl radical production in CuI nanoparticle suspension. Furthermore, amino acid oxidation in the viral capsid protein of FCV was determined by nanoflow liquid chromatography-mass spectrometric (nano LC-MS) analysis. The use of CuI nanoparticles showed extremely high antiviral activity against FCV. The high antiviral property of CuI nanoparticles was attributed to Cu(+), followed by ROS generation and subsequent capsid protein oxidation. CuI nanoparticles could be proposed as useful sources of a continuous supply of Cu(+) ions for efficient virus inactivation. Furthermore, this study brings new insights into toxic actions of copper iodide nanoparticles against viruses.

DOI： 10.1016/j.jbiosc.2011.12.006

Prevention of marine biofouling on nylon mesh doped with silver iodide 査読

Tetsuya Sato, Yoshie Fujimori, Tsuruo Nakayama, Yasuo Gotoh, Michiko Nemoto, Tadashi Matsunaga, Tsuyoshi Tanaka

COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS 396 41 - 45 2012年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Many textiles have been often used in marine environments for a wide variety of purposes. Consequently, effective and clean methods to prevent biofouling in these textiles are needed. In this study, a nylon mesh doped with AgI was examined for its antifouling performance. The nylon mesh was iodinated with an iodine-potassium iodide aqueous solution and subsequently immersed in silver nitrate solution to form AgI particles in the fiber. SEM-EDX analysis indicated that the AgI crystals were highly incorporated into the nylon 6,6 polymer (173 wt% gain). The bactericidal activity of AgI-doped nylon mesh was more than 200 times higher than that of silver-coated nylon mesh. Furthermore, continuous prevention of biofouling in the coastal marine environment was attained for 437 days by using the AgI-doped nylon mesh. Since the concentration of the released silver ions from the nylon mesh was estimated to be less than 1 ppb, the proposed nylon mesh is useful as an effective and clean method for prevention of biofouling in polymer textiles. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2011.12.037

次世代液体バイオ燃料開発に向けた海洋生物資源の活用

田中剛, 根本理子, 松永是

ケミカルエンジニアリング 56 ( 9 ) 713 - 718 2011年9月

Proteomic analysis of irregular, bullet-shaped magnetosomes in the sulphate-reducing magnetotactic bacterium Desulfovibrio magneticus RS-1. 査読国際誌

Tadashi Matsunaga, Michiko Nemoto, Atsushi Arakari, Masayoshi Tanaka

Proteomics 9 ( 12 ) 3341 - 52 2009年6月

記述言語：英語掲載種別：研究論文（学術雑誌）

Recent molecular studies on magnetotactic bacteria have identified a number of proteins associated with bacterial magnetites (magnetosomes) and elucidated their importance in magnetite biomineralisation. However, these analyses were limited to magnetotactic bacterial strains belonging to the alpha-subclass of Proteobacteria. We performed a proteomic analysis of magnetosome membrane proteins in Desulfovibrio magneticus strain RS-1, which is phylogenetically classified as a member of the delta-Proteobacteria. In the analysis, the identified proteins were classified based on their putative functions and compared with the proteins from the other magnetotactic bacteria, Magnetospirillum magneticum AMB-1 and M. gryphiswaldense MSR-1. Three magnetosome-specific proteins, MamA (Mms24), MamK, and MamM, were identified in strains RS-1, AMB-1, and MSR-1. Furthermore, genes encoding ten magnetosome membrane proteins, including novel proteins, were assigned to a putative magnetosome island that contains subsets of genes essential for magnetosome formation. The collagen-like protein and putative iron-binding proteins, which are considered to play key roles in magnetite crystal formation, were identified as specific proteins in strain RS-1. Furthermore, genes encoding two homologous proteins of Magnetococcus MC-1 were assigned to a cryptic plasmid of strain RS-1. The newly identified magnetosome membrane proteins might contribute to the formation of the unique irregular, bullet-shaped crystals in this microorganism.

DOI： 10.1002/pmic.200800881

Formation of magnetite by bacteria and its application. 査読国際誌

Atsushi Arakaki, Hidekazu Nakazawa, Michiko Nemoto, Tetsushi Mori, Tadashi Matsunaga

Journal of the Royal Society, Interface 5 ( 26 ) 977 - 99 2008年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC

Magnetic particles offer high technological potential since they can be conveniently collected with an external magnetic field. Magnetotactic bacteria synthesize bacterial magnetic particles (BacMPs) with well-controlled size and morphology. BacMPs are individually covered with thin organic membrane, which confers high and even dispersion in aqueous solutions compared with artificial magnetites, making them ideal biotechnological materials. Recent molecular studies including genome sequence, mutagenesis, gene expression and proteome analyses indicated a number of genes and proteins which play important roles for BacMP biomineralization. Some of the genes and proteins identified from these studies have allowed us to express functional proteins efficiently onto BacMPs, through genetic engineering, permitting the preservation of the protein activity, leading to a simple preparation of functional protein-magnetic particle complexes. They were applicable to high-sensitivity immunoassay, drug screening and cell separation. Furthermore, fully automated single nucleotide polymorphism discrimination and DNA recovery systems have been developed to use these functionalized BacMPs. The nano-sized fine magnetic particles offer vast potential in new nano-techniques.

DOI： 10.1098/rsif.2008.0170

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