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

J. Biol. Chem., Vol. 281, Issue 47, 36249-36256, November 24, 2006

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 281/47/36249    most recent M606906200v1 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 Google Scholar Google Scholar Articles by Mori, H. Articles by Ito, K. Search for Related Content PubMed PubMed Citation Articles by Mori, H. Articles by Ito, K. Social Bookmarking                      What's this?

The Long -Helix of SecA Is Important for the ATPase Coupling of Translocation^*

From the Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan

SecA contains two ATPase folds (NBF1 and NBF2) and other interaction/regulatory domains, all of which are connected by a long helical scaffold domain (HSD) running along the molecule. Here we identified a functionally important and spatially adjacent pair of SecA residues, Arg-642 on HSD and Glu-400 on NBF1. A charge-reversing substitution at either position as well as disulfide tethering of these positions inactivated the translocation activity. Interestingly, however, the translocation-inactive SecA variants fully retained the ability to up-regulate the ATPase in response to a preprotein and the SecYEG translocon. The translocation defect was suppressible by second site alterations at the hinge-forming boundary of NBF2 and HSD. Based on these results, we propose that the motor function of SecA is realized by ligand-activated ATPase engine and its HSD-mediated conversion into the mechanical work of preprotein translocation.

Received for publication, July 20, 2006 , and in revised form, September 27, 2006.

^* This work was supported by grants from the Japan Society for the Promotion of Science (to H. M.) and from the Ministry of Education, Culture, Sports, Science and Technology, Japan (to K. I.) as well as by CREST, Japan Science and Technology Agency, and by National Project on Protein Structural and Functional Analyses of the Ministry of Education, Culture, Sports, Science and Technology, Japan (to K. I.). 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.

The on-line version of this article (available at http://www.jbc.org) contains a supplemental figure, supplemental text, and a reference.

¹ To whom correspondence should be addressed: Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan. Tel.: 81-75-751-4015; Fax: 81-75-771-5699; E-mail: kito{at}virus.kyoto-u.ac.jp.

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