Faculty Profiles - KOJIMA, Seiji

Papers - KOJIMA, Seiji

Division display 101 - 120 of about 223 ／ All the affair displays >>

Mutation in the a-subunit of F1FO-ATPase causes an increased motility phenotype through the sodium-driven flagella of Vibrio. Reviewed

Terashima H, Terauchi T, Ihara K, Nishioka N, Kojima S, Homma M.

J. Biochem. Vol. 154 page： 177-184 2013

Insight into the assembly mechanism in the supramolecular rings of the sodium-driven Vibrio flagellar motor from the structure of FlgT. Reviewed Open Access

Terashima H, Li N, Sakuma M, Koike M, Kojima S, Homma M, Imada K.

Proc. Natl. Acad. Sci. U. S. A. Vol. 110 page： 6133-6138 2013

Fluorescence imaging of GFP-fused periplasmic components of Na+-driven flagellar motor using Tat pathway in Vibrio alginolyticus. Reviewed

Takekawa N, Kojima S, Homma M.

J. Biochem. Vol. 153 page： 547-553 2013

Expression, purification and biochemical characterization of the cytoplasmic loop of PomA, a stator component of the Na+ driven flagellar motor. Reviewed

Abe-Yoshizumi R, Kobayashi S, Gohara M, Hayashi K, Kojima C, Kojima S, Sudo Y, Asami Y, Homma M.

Biophysics Vol. 9 page： 21-29 2013

Na+ conductivity of the Na+-driven flagellar motor complex composed of unplugged wild-type or mutant PomB with PomA. Reviewed

Takekawa N, Terauchi T, Morimoto YV, Minamino T, Lo CJ, Kojima S, Homma M.

J. Biochem. Vol. 153 page： 441-451 2013

A novel dnaJ family gene, sflA, encodes an inhibitor of flagellation in marine Vibrio species. Reviewed

Kitaoka M, Nishigaki T, Ihara K, Nishioka N, Kojima S, Homma M.

J. Bacteriol. Vol. 195 page： 816-822 2013

Expression, purification and biochemical characterization of the cytoplasmic loop of PomA, a stator component of the Na+ driven flagellar motor Reviewed Open Access

Rei Abe-Yoshizumi, Shiori Kobayashi, Mizuki Gohara, Kokoro Hayashi, Chojiro Kojima, Seiji Kojima, Yuki Sudo, Yasuo Asami, Michio Homma

Biophysics (Japan) Vol. 9 page： 21 - 29 2013

Language：English Publishing type：Research paper (scientific journal)

Flagellar motors embedded in bacterial membranes are molecular machines powered by specific ion flows. Each motor is composed of a stator and a rotor and the interactions of those components are believed to generate the torque. Na+ influx through the PomA/PomB stator complex of Vibrio alginolyticus is coupled to torque generation and is speculated to trigger structural changes in the cytoplasmic domain of PomA that interacts with a rotor protein in the C-ring, FliG, to drive the rotation. In this study, we tried to overproduce the cytoplasmic loop of PomA (PomA-Loop), but it was insoluble. Thus, we made a fusion protein with a small soluble tag (GB1) which allowed us to express and characterize the recombinant protein. The structure of the PomA-Loop seems to be very elongated or has a loose tertiary structure. When the PomA-Loop protein was produced in E. coli, a slight dominant effect was observed on motility. We conclude that the cytoplasmic loop alone retains a certain function. © 2013 THE BIOPHYSICAL SOCIETY OF JAPAN.

DOI： 10.2142/biophysics.9.21

Open Access

Scopus

PubMed

Intragenic Suppressor of a Plug Deletion Nonmotility Mutation in PotB, a Chimeric Stator Protein of Sodium-Driven Flagella Reviewed Open Access

Shiwei Zhu, Michio Homma, Seiji Kojima

JOURNAL OF BACTERIOLOGY Vol. 194 ( 24 ) page： 6728 - 6735 2012.12

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER SOC MICROBIOLOGY

The torque of bacterial flagellar motors is generated by interactions between the rotor and the stator and is coupled to the influx of H+ or Na+ through the stator. A chimeric protein, PotB, in which the N-terminal region of Vibrio alginolyticus PomB was fused to the C-terminal region of Escherichia coli MotB, can function with PomA as a Na+-driven stator in E. coli. Here, we constructed a deletion variant of PotB (with a deletion of residues 41 to 91 [Delta 41-91], called PotB Delta L), which lacks the periplasmic linker region including the segment that works as a "plug" to inhibit premature ion influx. This variant did not confer motile ability, but we isolated a Na+-driven, spontaneous suppressor mutant, which has a point mutation (R109P) in the MotB/PomB-specific alpha-helix that connects the transmembrane and peptidoglycan binding domains of PotB Delta L in the region of MotB. Overproduction of the PomA/PotB Delta L(R109P) stator inhibited the growth of E. coli cells, suggesting that this stator has high Na+-conducting activity. Mutational analyses of Arg109 and nearby residues suggest that the structural alteration in this alpha-helix optimizes PotB Delta L conformation and restores the proper arrangement of transmembrane helices to form a functional channel pore. We speculate that this alpha-helix plays a key role in assembly-coupled stator activation.

DOI： 10.1128/JB.01132-12

Web of Science

PubMed

Bacterial Motility Measured by a Miniature Chamber for High-Pressure Microscopy Reviewed Open Access

Masayoshi Nishiyama, Seiji Kojima

INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol. 13 ( 7 ) page： 9225 - 9239 2012.7

Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI AG

Hydrostatic pressure is one of the physical stimuli that characterize the environment of living matter. Many microorganisms thrive under high pressure and may even physically or geochemically require this extreme environmental condition. In contrast, application of pressure is detrimental to most life on Earth; especially to living organisms under ambient pressure conditions. To study the mechanism of how living things adapt to high-pressure conditions, it is necessary to monitor directly the organism of interest under various pressure conditions. Here, we report a miniature chamber for high-pressure microscopy. The chamber was equipped with a built-in separator, in which water pressure was properly transduced to that of the sample solution. The apparatus developed could apply pressure up to 150 MPa, and enabled us to acquire bright-field and epifluorescence images at various pressures and temperatures. We demonstrated that the application of pressure acted directly and reversibly on the swimming motility of Escherichia coli cells. The present technique should be applicable to a wide range of dynamic biological processes that depend on applied pressures.

DOI： 10.3390/ijms13079225

Open Access

Web of Science

PubMed

Characterization of PomA Mutants Defective in the Functional Assembly of the Na+-Driven Flagellar Motor in Vibrio alginolyticus Reviewed Open Access

Norihiro Takekawa, Na Li, Seiji Kojima, Michio Homma

JOURNAL OF BACTERIOLOGY Vol. 194 ( 8 ) page： 1934 - 1939 2012.4

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER SOC MICROBIOLOGY

The polar flagellar motor of Vibrio alginolyticus rotates using Na+ influx through the stator, which is composed of 2 subunits, PomA and PomB. About a dozen stators dynamically assemble around the rotor, depending on the Na+ concentration in the surrounding environment. The motor torque is generated by the interaction between the cytoplasmic domain of PomA and the C-terminal region of FliG, a component of the rotor. We had shown previously that mutations of FliG affected the stator assembly around the rotor, which suggested that the PomA-FliG interaction is required for the assembly. In this study, we examined the effects of various mutations mainly in the cytoplasmic domain of PomA on that assembly. All mutant stators examined, which resulted in the loss of motor function, assembled at a lower level than did the wild-type PomA. A His tag pulldown assay showed that some mutations in PomA reduced the PomA-PomB interaction, but other mutations did not. Next, we examined the ion conductivity of the mutants using a mutant stator that lacks the plug domain, PomA/PomB(Delta L)(Delta 41-120), which impairs cell growth by overproduction, presumably because a large amount of Na+ is conducted into the cells. Some PomA mutations suppressed this growth inhibition, suggesting that such mutations reduce Na+ conductivity, so that the stators could not assemble around the rotor. Only the mutation H136Y did not impair the stator formation and ion conductivity through the stator. We speculate that this particular mutation may affect the PomA-FliG interaction and prevent activation of the stator assembly around the rotor.

DOI： 10.1128/JB.06552-11

Web of Science

PubMed

Instantaneous and Quantitative Single Cells Viability Determination Using Dual Nanoprobe Inside ESEM Reviewed

Mohd Ridzuan Ahmad, Masahiro Nakajima, Masaru Kojima, Seiji Kojima, Michio Homma, Toshio Fukuda

IEEE TRANSACTIONS ON NANOTECHNOLOGY Vol. 11 ( 2 ) page： 298 - 306 2012.3

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

We performed single pulses current measurement on single cells using dual nanoprobe through environmental scanning electron microscope nanomanipulator system. The ability to characterize the electrical property of single cells can be used as a novel method for cell viability detection in quantitative and instantaneous manners. The nanoprobe was successfully fabricated using focused ion beam tungsten deposition and etching processes. The characteristics of the nanoprobe were examined from the energy dispersion spectrometry and noise analyses. In this paper, for the first time, the electrical property of single cells under their native condition was presented. In order to apply this method for cell viability detection, two types of cells were used, i.e., dead cells and live cells. The results showed that there is a significant difference on the electrical measurement data between dead and live cells.

DOI： 10.1109/TNANO.2011.2171989

Web of Science

Nanofork for Single Cells Adhesion Measurement via ESEM-Nanomanipulator System Reviewed

Mohd Ridzuan Ahmad, Masahiro Nakajima, Masaru Kojima, Seiji Kojima, Michio Homma, Toshio Fukuda

IEEE TRANSACTIONS ON NANOBIOSCIENCE Vol. 11 ( 1 ) page： 70 - 78 2012.3

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

In this paper, single cells adhesion force was measured using a nanofork. The nanofork was used to pick up a single cell on a line array substrate inside an environmental scanning electron microscope (ESEM). The line array substrate was used to provide small gaps between the single cells and the substrate. Therefore, the nanofork could be inserted through these gaps in order to successfully pick up a single cell. Adhesion force was measured during the cell pick-up process from the deflection of the cantilever beam. The nanofork was fabricated using focused ion beam(FIB) etching process while the line array substrate was fabricated using nanoimprinting technology. As to investigate the effect of contact area on the strength of the adhesion force, two sizes of gap distance of line array substrate were used, i.e., 1 mu m and 2 mu m. Results showed that cells attached on the 1 mu m gap line array substrate required more force to be released as compared to the cells attached on the 1 mu m gap line array substrate.

DOI： 10.1109/TNB.2011.2179809

Web of Science

PubMed

ペリプラズム側構造から見たべん毛モーター構築とモーターの活性化機構 Reviewed Open Access

小嶋誠司、今田勝巳

生物物理 Vol. 52 ( 1 ) page： 18-21 2012.2

Assembly and Activation Mechanism of the Flagellar Stator Revealed by the Crystal Structure of Its Periplasmic Region Reviewed Open Access

KOJIMA Seiji, IMADA Katsumi

Seibutsu Butsuri Vol. 52 ( 1 ) page： 18 - 21 2012.1

Language：Japanese Publisher：The Biophysical Society of Japan General Incorporated Association

Bacterial flagellar motor is an ion-driven supramolecular nanomachine embedded in the cell envelope. Rotor-stator interaction that couples to the specific ion translocation through the stator channel is the nature of torque generation. To produce fully functional motor, multiple stator complexes must be incorporated around the rotor at appropriate places. However, such stator assembly mechanism has not been investigated by the structural point of view. Here we describe stator assembly and activation mechanism revealed from the crystal structure of a motor component located in the periplasmic space, suggesting the dynamic conformational changes in the stator during its assembly-coupled activation.<br>

DOI： 10.2142/biophys.52.018

Open Access

CiNii Research

Other Link： https://jlc.jst.go.jp/DN/JALC/00387646297?from=CiNii

Characterization of PomA mutants defective in the functional assembly of the Na+-driven flagellar motor in Vibrio alginolyticus Reviewed

Takekawa N, Li N, Kojima S, Homma M

Journal of Bacteriology Vol. 194 page： 1934-1939 2012

Nanofork for single cells adhesion measurement via ESEM-nanomanipulator system Reviewed

Ahmad MR, Nakajima M, Kojima M, Kojima S, Homma M, Fukuda T

IEEE Trans Nanobioscience Vol. 11 page： 70-78 2012

Intragenic suppressor of a plug deletion nonmotility mutation in PotB, a chimeric stator protein of sodium-driven flagella. Reviewed

Zhu S, Homma M, Kojima S

J. Bacteriol. Vol. 194 page： 6728-6735 2012

Bacterial motility measured by a miniature chamber for high-pressure microscopy. Reviewed Open Access

Nishiyama M and Kojima S

Int. J. Mol. Sci. Vol. 13 page： 9225-9239 2012

Evaluation of the Single Yeast Cell's Adhesion to ITO Substrates With Various Surface Energies via ESEM Nanorobotic Manipulation System. Reviewed

Shen Y, Ahmad MR, Nakajima M, Kojima S, Homma M, Fukuda T.

IEEE Trans Nanobioscience Vol. 10 ( 4 ) page： 217-224 2011.12

Evaluation of the Single Yeast Cell's Adhesion to ITO Substrates With Various Surface Energies via ESEM Nanorobotic Manipulation System Reviewed

Yajing Shen, Mohd Ridzuan Ahmad, Masahiro Nakajima, Seiji Kojima, Michio Homma, Toshio Fukuda

IEEE TRANSACTIONS ON NANOBIOSCIENCE Vol. 10 ( 4 ) page： 217 - 224 2011.12

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Cell-surface adhesion force is important for cell activities and the development of bio materials. In this paper, a method for in situ single cell (W303) adhesion force measurement was proposed based on nanorobotic manipulation system inside an environment scanning electron microscope (ESEM). An end effector was fabricated from a commercial atomic force microscope (AFM) cantilever by focused ion beam (FIB) etching. The spring constant of it was calibrated by nanomanipulation approach. Three kinds of hydrophilic and hydrophobic ITO plates were prepared by using VUV-irradiation and OTS coating techniques. The shear adhesion strength of the single yeast cell to each substrate was measured based on the deflection of the end effector. The results demonstrated that the cell adhesion force was larger under the wet condition in the ESEM environment than in the aqueous condition. It also showed that the cell adhesion force to hydrophilic surface was larger than that to the hydrophobic surface. Studies of single cell's adhesion on various plate surfaces and environments could give new insights into the tissue engineering and biological field.

DOI： 10.1109/TNB.2011.2177099

Web of Science

PubMed

　 PREV - NEXT 　

<KOJIMA, Seiji>

Papers - KOJIMA, Seiji