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

J. Biol. Chem., Vol. 281, Issue 51, 39380-39387, December 22, 2006

This Article Full Text Full Text (PDF) All Versions of this Article: 281/51/39380    most recent M607785200v1 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 Google Scholar Google Scholar Articles by Qian, X. Articles by Luo, Y. Search for Related Content PubMed PubMed Citation Articles by Qian, X. Articles by Luo, Y. Social Bookmarking                      What's this?

Calcium Stiffens Archaeal Rad51 Recombinase from Methanococcus voltae for Homologous Recombination^*

Xinguo Qian, Yujiong He, Xinfeng Ma, Michel N. Fodje, Pawel Grochulski, and Yu Luo, Recipient of CIHR new investigator salary award¹

From the Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada and the Canadian Light Source Inc., University of Saskatchewan, Saskatoon, Saskatchewan S7N 0X4, Canada

Archaeal RadA or Rad51 recombinases are close homologues of eukaryal Rad51 and DMC1. These and bacterial RecA orthologues play a key role in DNA repair by forming helical nucleoprotein filaments in which a hallmark strand exchange reaction between homologous DNA substrates occurs. Recent studies have discovered the stimulatory role by calcium on human and yeast recombinases. Here we report that the strand exchange activity but not the ATPase activity of an archaeal RadA/Rad51 recombinase from Methanococcus voltae (MvRadA) is also subject to calcium stimulation. Crystallized MvRadA filaments in the presence of CaCl₂ resemble that of the recently reported ATPase active form in the presence of an activating dose of KCl. At the ATPase center, one Ca²⁺ ion takes the place of two K⁺ ions in the K⁺-bound form. The terminal phosphate of the nonhydrolyzable ATP analogue is in a staggered conformation in the Ca²⁺-bound form. In comparison, an eclipsed conformation was seen in the K⁺-bound form. Despite the changes in the ATPase center, both forms harbor largely ordered L2 regions in essentially identical conformations. These data suggest a unified stimulation mechanism by potassium and calcium because of the existence of a conserved ATPase center promiscuous in binding cations.

Received for publication, August 15, 2006 , and in revised form, September 21, 2006.

The atomic coordinates and structure factors (code 2I1Q) have been deposited in the Protein Data Bank, Research Collaboratory for Structural Bioinformatics, Rutgers University, New Brunswick, NJ (http://www.rcsb.org/).

^* This work was supported in part by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Saskatchewan Health Research Foundation (SHRF), and the Canadian Institutes of Health Research (CIHR) operating grants (to Y. L.). Some of the research described in this paper was performed at the Canadian Light Source, which is supported by NSERC, National Research Council (NRC), CIHR, and the University of Saskatchewan. 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: Dept. of Biochemistry, University of Saskatchewan, A3 Health Sciences Bldg., 107 Wiggins Rd., Saskatoon, Saskatchewan S7N 5E5, Canada. Tel.: 306-966-4379; Fax: 306-966-4390; E-mail: Yu.Luo{at}usask.ca.

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