研究者詳細 - 小嶋　誠司

論文 - 小嶋　誠司

分割表示 222 件中 201 - 220 件目／全件表示 >>

Conformational change in the stator of the bacterial flagellar motor 査読有り

S Kojima, DF Blair

BIOCHEMISTRY 40 巻 ( 43 ) 頁： 13041 - 13050 2001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：AMER CHEMICAL SOC

MotA and MotB are integral membrane proteins of Escherichia coli that form the stator of the proton-fueled flagellar rotary motor. The motor contains several MotA/MotB complexes, which function independently to conduct protons across the cytoplasmic membrane and couple proton flow to rotation. MotB contains a conserved aspartic acid residue, Asp32, that is critical for rotation. We have proposed that the protons energizing the motor interact with Asp32 of MotB to induce conformational changes in the stator that drive movement of the rotor. To test for conformational changes, we examined the protease susceptibility of MotA in membrane-bound complexes with either wild-type MotB or MotB mutated at residue 32. Small, uncharged replacements of Asp32 in MotB (D32N, D32A, D32G, D32S, or D32C) caused a significant change in the conformation of MotA, as evidenced by a change in the pattern of proteolytic fragments. The conformational change does not require any flagellar proteins besides MotA and MotB, as it was still seen in a strain that expresses no other flagellar genes. It affects a cytoplasmic domain of MotA that contains residues known to interact with the rotor, consistent with a role in the generation of torque. Influences of key residues of MotA on conformation were also examined. Pro173 of MotA, known to be important for rotation, is a significant determinant of conformation: Dominant Pro173 mutations, but not recessive ones, altered the proteolysis pattern of MotA and also prevented the conformational change induced by Asp32 replacements. Arg90 and Glu98, residues of MotA that engage in electrostatic interactions with the rotor, appear not to be strong determinants of conformation of the MotA/MotB complex in membranes. We note sequence similarity between MotA and ExbB, a cytoplasmic-membrane protein that energizes outer-membrane transport in Gram-negative bacteria. ExbB and associated proteins might also employ a mechanism involving proton-driven conformational change.

Web of Science

*Conformational change in the stator of the bacterial flagellar motor. 査読有り

Kojima, S., & Blair, D.F.

Biochemistry 40 巻頁： 13041-13050 2001年

A slow-motility phenotype caused by substitutions at residue Asp31 in the PomA channel component of a sodium-driven flagellar motor 査読有り

S Kojima, T Shoji, Y Asai, Kawagishi, I, M Homma

JOURNAL OF BACTERIOLOGY 182 巻 ( 11 ) 頁： 3314 - 3318 2000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：AMER SOC MICROBIOLOGY

PomA is thought to be a component of the ion channel in the sodium-driven polar-flagellar motor of Vibrio alginolyticus. We have found that some cysteine substitutions in the periplasmic region of PomA result in a slow-motility phenotype, in which swarming and swimming speeds are reduced even in the presence of high concentrations of NaCl. Most of the mutants showed a sodium ion dependence similar to that of the wild type but with significantly reduced motility at all sodium ion concentrations. By contrast, motility of the D31C mutant showed a sharp dependence on NaCl concentration, with a threshold at 38 mM. The motor of the D31C mutant rotates stably, as monitored by laser dark-field microscopy, suggesting that the mutant PomA protein is assembled normally into the motor complex. Mutational studies of Asp31 suggest that, although this residue is not essential for motor rotation, a negative charge at this position contributes to optimal speed and/or efficiency of the motor.

Web of Science

A slow-motility phenotype caused by substitutions at residue Asp31 in the PomA channel component of a sodium-driven flagellar motor

Kojima S, Shoji T, Asai Y, Kawagishi I, Homma M

JOURNAL OF BACTERIOLOGY 182 巻 ( 11 ) 頁： 3314 - 3318 2000年6月

A slow-motility phenotype caused by substitutions at residue Asp31 in the PomA channel component of a sodium-driven flagellar motor.

Kojima, S., Shoji, T., Asai, Y., Kawagishi, I & Homma, M.

Journal of Bacteriology 182 巻頁： 3314-3318 2000年

Random mutagenesis of the pomA gene encoding a putative channel component of the Na+-driven polar flagellar motor of Vibrio alginolyticus 国際誌

Kojima, S; Kuroda, M; Kawagishi, I; Homma, M

MICROBIOLOGY-UK 145 巻頁： 1759 - 1767 1999年7月

The polar flagellar motor of Vibrio cholerae is driven by an Na+ motive force 査読有り

S Kojima, K Yamamoto, Kawagishi, I, M Homma

JOURNAL OF BACTERIOLOGY 181 巻 ( 6 ) 頁： 1927 - 1930 1999年3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

Vibrio cholerae is a highly motile bacterium which possesses a single polar flagellum as a locomotion organelle. Motility is thought to be an important factor for the virulence of V. cholerae. The genome sequencing project of this organism is in progress, and the genes that are highly homologous to the essential genes of the Na+-driven polar flagellar motor of Vibrio alginolyticus were found in the genome database of V. cholerae. The energy source of its flagellar motor was investigated, We examined the Na+ dependence and the sensitivity to the Na+ motor-specific inhibitor of the motility of the V. cholerae strains and present the evidence that the polar flagellar motor of V. cholerae is driven by an Na+ motive force.

Web of Science

Na+-driven flagellar motor resistant to phenamil, an amiloride analog, caused by mutations in putative channel components 査読有り

Kojima, S; Asai, Y; Atsumi, T; Kawagishi, I; Homma, M

JOURNAL OF MOLECULAR BIOLOGY 285 巻 ( 4 ) 頁： 1537 - 1547 1999年1月

*Na+-driven flagellar motor resistant to phenamil, an amiloride analog, caused by mutations of putative channel components. 査読有り

Kojima, S., Asai, Y., Atsumi, T., Kawagishi, I. & Homma, M.

Journal of Molecular Biology 285 巻頁： 1537-1547 1999年

The polar flagellar motor of Vibrio cholerae is driven by an Na+ motive force. 査読有り

Kojima, S., Yamamoto, K., Kawagishi, I. & Homma, M.

Journal of Bacteriology 181 巻頁： 1927-1930 1999年

Random mutagenesis of the pomA gene encoding a putative channel component of the Na+-driven polar flagellar motor of Vibrio alginolyticus. 査読有り

Kojima, S., Kuroda, M., Kawagishi, I. & Homma, M.

Microbiology 145 巻頁： 1759-1767 1999年

Putative channel components for the fast-rotating sodium-driven flagellar motor of a marine bacterium 査読有り

Y Asai, S Kojima, H Kato, N Nishioka, Kawagishi, I, M Homma

JOURNAL OF BACTERIOLOGY 179 巻 ( 16 ) 頁： 5104 - 5110 1997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：AMER SOC MICROBIOLOGY

The polar flagellum of Vibrio alginolyticus rotates remarkably fast (up to 1,700 revolutions per second) by using a motor driven by sodium ions, Two genes, motX and motY, for the sodium-driven flagellar motor have been identified in marine bacteria, Vibrio parahaemolyticus and V. alginolyticus. They have no similarity to the genes for proton-driven motors, motA and motB, whose products constitute a proton channel, MotX Has proposed to be a component of a sodium channel, Were we identified additional sodium motor genes, pomA and pomB, in V. alginolyticus. Unexpectedly, PomA and PomB have similarities to MotA and MotB, respectively, especially in the predicted transmembrane regions, These results suggest that PomA and PomB may be sodium-conducting channel components of the sodium-driven motor and that the motor part consists of the products of at least four genes, pomA, pomB, motX, and motY. Furthermore, swimming speed was controlled by the expression level of the pomA gene. suggesting that newly synthesized PomA proteins, which are components of a force-generating unit, were successively integrated into the defective motor complexes. These findings imply that Na+-driven flagellar motors mag have similar structure and function as proton driven motors, but with some interesting differences as well, and it is possible to compare and study the coupling mechanisms of the sodium and proton ion flux for the force generation.

Web of Science

Putative channel components for the fast-rotating sodium-driven flagellar motor of a marine bacterium

Asai Y, Kojima S, Kato H, Nishioka N, Kawagishi I, Homma M

JOURNAL OF BACTERIOLOGY 179 巻 ( 16 ) 頁： 5104 - 5110 1997年8月

Characterization of polar-flagellar-length mutants in Vibrio alginolyticus 査読有り

Furuno, M; Atsumi, T; Yamada, T; Kojima, S; Nishioka, N; Kawagishi, I; Homma, M

MICROBIOLOGY-SGM 143 巻 ( 5 ) 頁： 1615 - 1621 1997年5月

Vibrio alginolyticus mutants resistant to phenamil, a specific inhibitor of the sodium-driven flagellar motor

Kojima, S; Atsumi, T; Muramoto, K; Kudo, S; Kawagishi, I; Homma, M

JOURNAL OF MOLECULAR BIOLOGY 265 巻 ( 3 ) 頁： 310 - 318 1997年1月

Characterization of the polar-flagellar length mutants in Vibrio alginolitycus. 査読有り

Furuno, M., Atsumi, T., Kojima, S., Nishioka, N., Kawagishi, I. & Homma, M.

Microbiology 143 巻頁： 1615-1621 1997年

Vibrio alginolyticus mutants resistant to phenamil, a specific inhibitor of the sodium-driven flagellar motor. 査読有り

Kojima, S., Atsumi, T., Muramoto, K., Kudo, S., Kawagishi, I. & Homma, M.

Journal of Molecular Biology 265 巻頁： 310-318 1997年

Putative channel components for the fast-rotating sodium-driven flagellar motor of a marine bacterium. 査読有り

Asai, Y., Kojima, S., Kato, H., Nishioka, N., Kawagishi, I. & Homma, M.

Journal of Bacteriology 179 巻頁： 5104-5110 1997年

バクテリアのNa^+駆動型モーターとべん毛運動

小嶋誠司, 川岸郁朗, 本間道夫

化学と生物 34 巻 ( 11 ) 頁： 730 - 737 1996年11月

Chemotactic responses to an attractant and a repellent by the polar and lateral flagellar systems of Vibrio alginolyticus 査読有り

M Homma, H Oota, S Kojima, Kawagishi, I, Y Imae

MICROBIOLOGY-UK 142 巻頁： 2777 - 2783 1996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：SOC GENERAL MICROBIOLOGY

Chemotactic responses in Vibrio alginolyticus, which has lateral and polar flagellar systems in one cell, were investigated. A lateral-flagella-defective (Pof(+) Laf(-)) mutant, which has only a polar flagellum, usually swam forward by the pushing action of its flagellum and occasionally changed direction by backward swimming. When the repellent phenol was added, Pof(+) Laf(-) cells moved frequently forward and backward (tumbling state). The tumbling was derived from the frequent changing between counter-clockwise and clockwise (CW) rotation of the flagellar motor, as was confirmed by the tethered-cell method. Furthermore, we found that the tumbling cells did not adapt to the phenol stimulus. When the attractant serine was added, the phenol-treated cells ceased tumbling and swam smoothly, adapting to the attractant stimulus after several minutes. We isolated chemotaxis-defective (Che(-)) mutants from the Pof(+) Laf(-) mutant; the tumbling mutants were not isolated. One interesting mutant swam backwards continuously, with its flagellum leading the cell and its flagellar motor rotating CW continuously. A polar-flagella-defective mutant (Pof(-) Laf(+)) stopped swimming after phenol addition and then recovered swimming ability within 10 min, indicating that lateral flagella can adapt to the repellent stimulus. This may represent a functional difference between the two flagellar systems in Vibrio cells, and between the chemotaxis systems affecting the two types of flagella.

Web of Science

　前のページ - 次のページ　

<小嶋 誠司>

論文 - 小嶋 誠司

<小嶋　誠司>

論文 - 小嶋　誠司