Document Detail

Switch I closure simultaneously promotes strong binding to actin and ADP in smooth muscle myosin.
MedLine Citation:
PMID:  21536675     Owner:  NLM     Status:  MEDLINE    
The motor protein myosin uses energy derived from ATP hydrolysis to produce force and motion. Important conserved components (P-loop, switch I, and switch II) help propagate small conformational changes at the active site into large scale conformational changes in distal regions of the protein. Structural and biochemical studies have indicated that switch I may be directly responsible for the reciprocal opening and closing of the actin and nucleotide-binding pockets during the ATPase cycle, thereby aiding in the coordination of these important substrate-binding sites. Smooth muscle myosin has displayed the ability to simultaneously bind tightly to both actin and ADP, although it is unclear how both substrate-binding clefts could be closed if they are rigidly coupled to switch I. Here we use single tryptophan mutants of smooth muscle myosin to determine how conformational changes in switch I are correlated with structural changes in the nucleotide and actin-binding clefts in the presence of actin and ADP. Our results suggest that a closed switch I conformation in the strongly bound actomyosin-ADP complex is responsible for maintaining tight nucleotide binding despite an open nucleotide-binding pocket. This unique state is likely to be crucial for prolonged tension maintenance in smooth muscle.
Justin A Decarreau; Nicholas G James; Lynn R Chrin; Christopher L Berger
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2011-05-02
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  286     ISSN:  1083-351X     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-06-20     Completed Date:  2011-08-30     Revised Date:  2013-06-30    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  22300-7     Citation Subset:  IM    
Department of Biochemistry, University of Vermont College of Medicine, Burlington, Vermont 05405, USA.
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MeSH Terms
Actins / metabolism*
Adenosine Diphosphate / metabolism*
Conserved Sequence
Energy Metabolism
Models, Molecular
Muscle, Smooth / metabolism*
Mutagenesis, Site-Directed
Myosins / chemistry*,  genetics,  metabolism*
Protein Binding
Protein Conformation
Grant Support
Reg. No./Substance:
0/Actins; 58-64-0/Adenosine Diphosphate; EC

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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