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EMBO J. 2007 Jan 10;26(1):265-74.

Reversible movement of switch 1 loop of myosin determines actin interaction.

Author information

1
Department of Biochemistry, Eötvös Lorand University, Budapest, Hungary.

Abstract

The conserved switch 1 loop of P-loop NTPases is implicated as a central element that transmits information between the nucleotide-binding pocket and the binding site of the partner proteins. Recent structural studies have identified two states of switch 1 in G-proteins and myosin, but their role in the transduction mechanism has yet to be clarified. Single tryptophan residues were introduced into the switch 1 region of myosin II motor domain and studied by rapid reaction methods. We found that in the presence of MgADP, two states of switch 1 exist in dynamic equilibrium. Actin binding shifts the equilibrium towards one of the MgADP states, whereas ATP strongly favors the other. In the light of electron cryo-microscopic and X-ray crystallographic results, these findings lead to a specific structural model in which the equilibrium constant between the two states of switch 1 is coupled to the strength of the actin-myosin interaction. This has implications for the enzymatic mechanism of G-proteins and possibly P-loop NTPases in general.

PMID:
17213877
PMCID:
PMC1782383
DOI:
10.1038/sj.emboj.7601482
[Indexed for MEDLINE]
Free PMC Article

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