Dynamic behaviour of the head-tail junction of myosin.
It has generally been supposed that flexibility in the head-tail junction of myosin is provided by free rotation around the bonds of the polypeptide backbone of a few amino acid residues, but direct evidence for this is lacking. Here it is shown that the binding of an antibody in this region reveals a novel structure in which the bases of the heads are separated by 10 nm, with concomitant 9 nm shortening of the tail and movement of the sites of sharp bends in the tail a similar distance towards the heads. These results suggest that the junction is a dynamic structure in which between 60 and 130 residues of the coiled coil can separate to allow the heads to move apart. They suggest a site for the series elastic element of the cross-bridge, and have implications for the interactions of the two heads with actin subunits in the thin filaments, and the mechanism of movement of other two-headed motor proteins, such as kinesins.
Knight
P J
PJ
University of Bristol, Department of Clinical Veterinary Science, Langford, UK.
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000906:Antibodies / Q000276:immunology; D000939:Epitopes / Q000276:immunology; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009218:Myosins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D011487:Protein Conformation; D017433:Protein Structure, Secondary
D000199:Actins; D000906:Antibodies; D000939:Epitopes; D009218:Myosins