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

J. Biol. Chem., Vol. 282, Issue 44, 31920-31927, November 2, 2007

This Article Full Text Full Text (PDF) All Versions of this Article: 282/44/31920    most recent M706259200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted 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 Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wood, K. S. Articles by Dunn, S. D. Search for Related Content PubMed PubMed Citation Articles by Wood, K. S. Articles by Dunn, S. D. Social Bookmarking                      What's this?

Role of the Asymmetry of the Homodimeric b₂ Stator Stalk in the Interaction with the F₁ Sector of Escherichia coli ATP Synthase^*

From the Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada

The b subunit dimer in the peripheral stator stalk of Escherichia coli ATP synthase is essential for enzyme assembly and the rotational catalytic mechanism. Recent protein chemical evidence revealed the dimerization domain of b to contain a novel two-stranded right-handed coiled coil with offset helices. Here, the existence of this structure in more complete constructs of b containing the C-terminal domain, and therefore capable of binding to the peripheral F₁-ATPase, was supported by the more efficient formation of intersubunit disulfide bonds between cysteine residues that are proximal only in the offset arrangement and by the greater thermal stabilities of cross-linked heterodimers trapped in the offset configuration as opposed to homodimers with the helices trapped in-register. F₁-ATPase binding analyses revealed the offset heterodimers to bind F₁ more tightly than in-register homodimers. Mutations near the C terminus of b were incorporated specifically into either the N-terminally or the C-terminally shifted polypeptide, b^N or b^C, respectively, to determine the contribution of each position to F₁ binding. Deletion of the last four residues of b^N substantially weakened F₁ binding, whereas the effect of the deletion in b^C was modest. Similarly, benzophenone maleimide introduced at the C terminus of b^N, but not b^C, mediated cross-linking to the subunit of F₁. These results imply that the polypeptide in the b^N position is more important for F₁ binding than the one in the b^C position and illustrate the significance of the asymmetry of the b dimer in the enzyme.

Received for publication, July 30, 2007 , and in revised form, August 14, 2007.

^* This work was supported by Grant MT-10237 from the Canadian Institutes of Health Research. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed. Tel.: 519-661-3055; Fax: 519-661-3175; E-mail: sdunn{at}uwo.ca.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				S. B. Claggett, M. O. Plancher, S. D. Dunn, and B. D. Cain The b Subunits in the Peripheral Stalk of F1F0 ATP Synthase Preferentially Adopt an Offset Relationship J. Biol. Chem., June 12, 2009; 284(24): 16531 - 16540. [Abstract] [Full Text] [PDF]

				E. Kish-Trier and S. Wilkens Domain Architecture of the Stator Complex of the A1A0-ATP Synthase from Thermoplasma acidophilum J. Biol. Chem., May 1, 2009; 284(18): 12031 - 12040. [Abstract] [Full Text] [PDF]