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Mol Cell. 2005 Feb 18;17(4):603-9.

A flexible domain is essential for the large step size and processivity of myosin VI.

Author information

1
Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.

Abstract

Myosin VI moves processively along actin with a larger step size than expected from the size of the motor. Here, we show that the proximal tail (the approximately 80-residue segment following the IQ domain) is not a rigid structure but, rather, a flexible domain that permits the heads to separate. With a GCN4 coiled coil inserted in the proximal tail, the heads are closer together in electron microscopy (EM) images, and the motor takes shorter processive steps. Single-headed myosin VI S1 constructs take nonprocessive 12 nm steps, suggesting that most of the processive step is covered by a diffusive search for an actin binding site. Based on these results, we present a mechanical model that describes stepping under an applied load.

PMID:
15721263
DOI:
10.1016/j.molcel.2005.01.015
[Indexed for MEDLINE]
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