Primary Citation of Related Structures: 1S5G, 1SR6
PubMed Abstract:
Structural studies of myosin have indicated some of the conformational changes that occur in this protein during the contractile cycle, and we have now observed a conformational change in a bound nucleotide as well. The 3.1-A x-ray structure of the scallop myosin head domain (subfragment 1) in the ADP-bound near-rigor state (lever arm =45 degrees to the helical actin axis) shows the diphosphate moiety positioned on the surface of the nucleotide-binding pocket, rather than deep within it as had been observed previously ...
Structural studies of myosin have indicated some of the conformational changes that occur in this protein during the contractile cycle, and we have now observed a conformational change in a bound nucleotide as well. The 3.1-A x-ray structure of the scallop myosin head domain (subfragment 1) in the ADP-bound near-rigor state (lever arm =45 degrees to the helical actin axis) shows the diphosphate moiety positioned on the surface of the nucleotide-binding pocket, rather than deep within it as had been observed previously. This conformation strongly suggests a specific mode of entry and exit of the nucleotide from the nucleotide-binding pocket through the so-called "front door." In addition, using a variety of scallop structures, including a relatively high-resolution 2.75-A nucleotide-free near-rigor structure, we have identified a conserved complex salt bridge connecting the 50-kDa upper and N-terminal subdomains. This salt bridge is present only in crystal structures of muscle myosin isoforms that exhibit a strong reciprocal relationship (also known as coupling) between actin and nucleotide affinity.
Related Citations:
Crystal structure of scallop Myosin s1 in the pre-power stroke state to 2.6 a resolution: flexibility and function in the head Gourinath, S., Himmel, D.M., Brown, J.H., Reshetnikova, L., Szent-Gyorgyi, A.G., Cohen, C. (2003) Structure 11: 1621
Crystallographic findings on the internally uncoupled and near-rigor states of myosin: further insights into the mechanics of the motor Himmel, D.M., Gourinath, S., Reshetnikova, L., Shen, Y., Szent-Gyorgyi, A.G., Cohen, C. (2002) Proc Natl Acad Sci U S A 99: 12645
Organizational Affiliation:
Rosenstiel Basic Medical Sciences Research Center, MS 029, Waltham, MA 02454-9110, USA.
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