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Reversible movement of switch 1 loop of myosin determines actin interaction
Author(s) -
Kintses Bálint,
Gyimesi Máté,
Pearson David S,
Geeves Michael A,
Zeng Wei,
Bagshaw Clive R,
MálnásiCsizmadia András
Publication year - 2007
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601482
Subject(s) - biology , myosin , actin , microbiology and biotechnology , loop (graph theory) , biophysics , movement (music) , physics , mathematics , acoustics , combinatorics
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.