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

J. Biol. Chem., Vol. 283, Issue 40, 26902-26910, October 3, 2008

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 283/40/26902    most recent M802957200v1 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 Taft, M. H. Articles by Tsiavaliaris, G. Search for Related Content PubMed PubMed Citation Articles by Taft, M. H. Articles by Tsiavaliaris, G. Social Bookmarking                      What's this?

Dictyostelium Myosin-5b Is a Conditional Processive Motor^*

From the Institute for Biophysical Chemistry, OE 4350, Hannover Medical School, Feodor-Lynen-Str. 5, D-30625 Hannover, Germany

Dictyostelium myosin-5b is the gene product of myoJ and one of two closely related myosin-5 isoenzymes produced in Dictyostelium discoideum. Here we report a detailed investigation of the kinetic and functional properties of the protein. In standard assay buffer conditions, Dictyostelium myosin-5b displays high actin affinity in the presence of ADP, fast ATP hydrolysis, and a high steady-state ATPase activity in the presence of actin that is rate limited by ADP release. These properties are typical for a processive motor that can move over long distances along actin filaments without dissociating. Our results show that a physiological decrease in the concentration of free Mg²⁺-ions leads to an increased rate of ADP release and shortening of the fraction of time the motor spends in the strong actin binding states. Consistently, the ability of the motor to efficiently translocate actin filaments at very low surface densities decreases with decreasing concentrations of free Mg²⁺-ions. In addition, we provide evidence that the observed changes in Dd myosin-5b motor activity are of physiological relevance and propose a mechanism by which this molecular motor can switch between processive and non-processive movement.

Received for publication, April 17, 2008 , and in revised form, July 15, 2008.

^* The work was supported by Deutsche Forschungsgemeinschaft Grants TS 169/3-1 (to G. T.) and MA 1081/11 (to D. J. M.). 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 Movies 1 and 2.

¹ To whom correspondence should be addressed: Institut für Biophysikalische Chemie, OE 4350, Medizinische Hochschule Hannover, CarlNeuberg-Straße 1, D-30625 Hannover, Germany. Tel.: 49-511-532-8591; Fax: 49-511-532-5966; E-mail: gtsiaval{at}bpc.mh-hannover.de.

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