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

J. Biol. Chem., Vol. 283, Issue 13, 8153-8163, March 28, 2008

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 283/13/8153    most recent M708863200v1 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 Gyimesi, M. Articles by Málnási-Csizmadia, A. Search for Related Content PubMed PubMed Citation Articles by Gyimesi, M. Articles by Málnási-Csizmadia, A. Social Bookmarking                      What's this?

The Mechanism of the Reverse Recovery Step, Phosphate Release, and Actin Activation of Dictyostelium Myosin II^*

Máté Gyimesi, Bálint Kintses, Andrea Bodor, András Perczel^¶, Stefan Fischer^||, Clive R. Bagshaw^**1, and András Málnási-Csizmadia²

From the Department of Biochemistry, Institute of Biology, the Laboratory of Structural Chemistry and Biology, Institute of Chemistry, and the ^¶Protein Modelling Group MTA-ELTE, Institute of Chemistry, Eötvös University, Pázmány Péter sétány 1/A, Budapest H-1117, Hungary, the ^||Computational Biochemisry, Interdisciplinary Center for Scientific Computing, University of Heidelberg, Heidelberg 69120, Germany, and the ^**Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, United Kingdom

The rate-limiting step of the myosin basal ATPase (i.e. in absence of actin) is assumed to be a post-hydrolysis swinging of the lever arm (reverse recovery step), that limits the subsequent rapid product release steps. However, direct experimental evidence for this assignment is lacking. To investigate the binding and the release of ADP and phosphate independently from the lever arm motion, two single tryptophan-containing motor domains of Dictyostelium myosin II were used. The single tryptophans of the W129+ and W501+ constructs are located at the entrance of the nucleotide binding pocket and near the lever arm, respectively. Kinetic experiments show that the rate-limiting step in the basal ATPase cycle is indeed the reverse recovery step, which is a slow equilibrium step (kforward = 0.05 s^–1, kreverse = 0.15 s^–1) that precedes the phosphate release step. Actin directly activates the reverse recovery step, which becomes practically irreversible in the actin-bound form, triggering the power stroke. Even at low actin concentrations the power stroke occurs in the actin-attached states despite the low actin affinity of myosin in the pre-power stroke conformation.

Received for publication, October 26, 2007 , and in revised form, January 10, 2008.

^* This work was supported in part by National Office for Research and Technology (Grants RET 14/2005 and OTKA TS49812 to A. M. C.) and by the Hungarian National Research Foundation (Grant D48459 to B. A.). 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 supplemental text and Figs. S1–S5.

¹ Supported by the Biotechnology and Biological Sciences and Research Council.

² To whom correspondence should be addressed. Tel.: 36-1-209-0555/8780; Fax: 36-1-381-2172; E-mail: malna{at}elte.hu.

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

This article has been cited by other articles:

				B. Kintses, Z. Yang, and A. Malnasi-Csizmadia Experimental Investigation of the Seesaw Mechanism of the Relay Region That Moves the Myosin Lever Arm J. Biol. Chem., December 5, 2008; 283(49): 34121 - 34128. [Abstract] [Full Text] [PDF]