Changes in Mg2+ ion concentration and heavy chain phosphorylation regulate the motor activity of a class I myosin

Fujita-Becker, Setsuko and Durrwang, Ulrike and Erent, Muriel and Clark, Richard J. and Geeves, Michael A. and Manstein, Dietmar J. (2005) Changes in Mg2+ ion concentration and heavy chain phosphorylation regulate the motor activity of a class I myosin. Journal of Biological Chemistry, 280 (7). pp. 6064-71. ISSN 0021-9258. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Class I myosins are single-headed motor proteins implicated in various motile processes including organelle translocation, ion channel gating, and cytoskeleton reorganization. Dictyostelium discoideum myosin-ID belongs to subclass 1alpha, whose members are thought to be tuned for rapid sliding. The direct analysis of myosin-ID motor activity is made possible by the production of single polypeptide constructs carrying an artificial lever arm. Using these constructs, we show that the motor activity of myosin-ID is activated 80-fold by phosphorylation at the TEDS site. TEDS site phosphorylation acts by stabilizing the actomyosin complex and increasing the coupling between actin binding and the release of hydrolysis products. A surprising effect of Mg(2+) ions on in vitro motility was discovered. Changes in the level of free Mg(2+) ions within the physiological range are shown to modulate motor activity by inhibiting ADP release. Our results indicate that higher concentrations of free Mg(2+) ions stabilize the tension-bearing actin myosin ADP state and shift the system from the production of rapid movement toward the generation of tension.

Item Type: Article
Additional information: 0021-9258 (Print) Journal Article
Uncontrolled keywords: Actins/metabolism Actomyosin/metabolism Adenosine Diphosphate/metabolism Adenosine Triphosphate/metabolism Amino Acid Sequence Animals Cations, Divalent/*metabolism Dictyostelium Kinetics Magnesium/*metabolism/pharmacology Molecular Motors/chemistry/genetics/metabolism Movement/drug effects Mutation/genetics Myosin Heavy Chains/chemistry/genetics/*metabolism Myosin Type I/chemistry/genetics/*metabolism Phosphorylation/drug effects Protein Binding Research Support, Non-U.S. Gov't Thermodynamics Titrimetry
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: Michael Geeves
Date Deposited: 04 Apr 2009 19:05
Last Modified: 20 May 2014 15:54
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