HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 275, Issue 40, 31387-31391, October 6, 2000

This Article Full Text Full Text (PDF) All Versions of this Article: 275/40/31387    most recent M000848200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Yorimitsu, T. Articles by Homma, M. Search for Related Content PubMed PubMed Citation Articles by Yorimitsu, T. Articles by Homma, M. Social Bookmarking                      What's this?

Intermolecular Cross-linking between the Periplasmic Loop_3-4 Regions of PomA, a Component of the Na⁺-driven Flagellar Motor of Vibrio alginolyticus^*

Tomohiro Yorimitsu, Yukako Asai, Ken Sato, and Michio Homma

From the Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-Ku, Nagoya 464-8602, Japan

PomA and PomB form a complex that conducts sodium ions and generates the torque for the Na⁺-driven polar flagellar motor of Vibrio alginolyticus. PomA has four transmembrane segments. One periplasmic loop (loop_1-2) connects segments 1 and 2, and another (loop_3-4), in which cysteine-scanning mutagenesis had been carried out, connects segments 3 and 4. When PomA with an introduced Cys residue (Cys-PomA) in the C-terminal periplasmic loop (loop_3-4) was examined without exposure to a reducing reagent, a 43-kDa band was observed, whereas only a 25-kDa band, which corresponds to monomeric PomA, was observed under reducing conditions. The intensity of the 43-kDa band was enhanced in most mutants by the oxidizing reagent CuCl₂. The 43-kDa band was strongest in the P172C mutant. The motility of the P172C mutant was severely reduced, and P172C showed a dominant-negative effect, whereas substitution of Pro with Ala, Ile, or Ser at this position did not affect motility. In the presence of DTT, the ability to swim was partially restored, and the amount of 43-kDa protein was reduced. These results suggest that the disulfide cross-link disturbs the function of PomA. When the mutated Cys residue was modified with N-ethylmaleimide, only the 25-kDa PomA band was labeled, demonstrating that the 43-kDa form is a cross-linked homodimer and suggesting that the loops_3-4 of adjacent subunits of PomA are close to each other in the assembled motor. We propose that this loop region is important for dimer formation and motor function.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				M. Obara, T. Yakushi, S. Kojima, and M. Homma Roles of Charged Residues in the C-Terminal Region of PomA, a Stator Component of the Na+-Driven Flagellar Motor J. Bacteriol., May 15, 2008; 190(10): 3565 - 3571. [Abstract] [Full Text] [PDF]

				T. Yakushi, S. Maki, and M. Homma Interaction of PomB with the Third Transmembrane Segment of PomA in the Na+-Driven Polar Flagellum of Vibrio alginolyticus J. Bacteriol., August 15, 2004; 186(16): 5281 - 5291. [Abstract] [Full Text] [PDF]

				T. Yorimitsu, M. Kojima, T. Yakushi, and M. Homma Multimeric Structure of the PomA/PomB Channel Complex in the Na+-Driven Flagellar Motor of Vibrio alginolyticus J. Biochem., January 1, 2004; 135(1): 43 - 51. [Abstract] [Full Text] [PDF]

				L. L. McCarter Polar Flagellar Motility of the Vibrionaceae Microbiol. Mol. Biol. Rev., September 1, 2001; 65(3): 445 - 462. [Abstract] [Full Text] [PDF]