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J Mol Biol. 2008 Jan 11;375(2):325-30. Epub 2007 Sep 29.

A cytoskeletal demolition worker: myosin II acts as an actin depolymerization agent.

Author information

1
Department of Chemical Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel.

Abstract

Myosin II motors play several important roles in a variety of cellular processes, some of which involve active assembly/disassembly of cytoskeletal substructures. Myosin II motors have been shown to function in actin bundle turnover in neuronal growth cones and in the recycling of actin filaments during cytokinesis. Close examination had shown an intimate relationship between myosin II motor adenosine triphosphatase activity and actin turnover rate. However, the direct implication of myosin II in actin turnover is still not understood. Herein, we show, using high-resolution cryo-transmission electron microscopy, that myosin II motors control the turnover of actin bundles in a concentration-dependent manner in vitro. We demonstrate that disassembly of actin bundles occurs through two main stages: the first stage involves unbundling into individual filaments, and the second involves their subsequent depolymerization. These evidence suggest that, in addition to their "classical" contractile abilities, myosin II motors may be directly implicated in active actin depolymerization. We believe that myosin II motors may function similarly in vivo (e.g., in the disassembly of the contractile ring by fine tuning the local concentration/activity of myosin II motors).

PMID:
18021803
DOI:
10.1016/j.jmb.2007.09.066
[Indexed for MEDLINE]

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