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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Actins / chemistry
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Actins / metabolism*
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Actins / ultrastructure
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Animals
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism
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Binding Sites
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Luminescent Proteins / genetics
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Luminescent Proteins / metabolism
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Microscopy, Electron
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Myosin Type V / chemistry
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Myosin Type V / genetics
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Myosin Type V / metabolism*
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Plasmids
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Protein Kinases / genetics
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Protein Kinases / metabolism
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Protein Structure, Tertiary
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism
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Swine
Substances
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Actins
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Bacterial Proteins
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DNA-Binding Proteins
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Luminescent Proteins
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Saccharomyces cerevisiae Proteins
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yellow fluorescent protein, Bacteria
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Protein Kinases
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Myosin Type V