Swing of the lever arm of a myosin motor at the isomerization and phosphate-release steps

In muscle, the myosin head ('crossbridge') performs the 'working stroke', in which ATP is hydrolysed to generate the sliding of actin and myosin filaments. The myosin head consists of a globular motor domain and a long lever-arm domain. The 'lever-arm hypothesis' predic...

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Bibliographic Details
Published in:Nature (London) 1998-11, Vol.396 (6709), p.380-383
Main Authors: Sutoh, Kazuo, Suzuki, Yoshikazu, Yasunaga, Takuo, Ohkura, Reiko, Wakabayashi, Takeyuki
Format: Article
Language:English
Subjects:
Adenosine Triphosphate - metabolism
Animals
ATP
Biochemistry
Biological and medical sciences
Chemicals
Cloning, Molecular
Conformational dynamics in molecular biology
Dictyostelium
Energy Transfer
Fluorescence
Fundamental and applied biological sciences. Psychology
Green Fluorescent Proteins
Humanities and Social Sciences
letter
Luminescent Proteins
Models, Molecular
Molecular biophysics
Molecular Motor Proteins
multidisciplinary
Muscular system
Myosins - metabolism
Myosins - physiology
Protein Conformation
Recombinant Fusion Proteins
Science
Science (multidisciplinary)
Space life sciences
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Summary:In muscle, the myosin head ('crossbridge') performs the 'working stroke', in which ATP is hydrolysed to generate the sliding of actin and myosin filaments. The myosin head consists of a globular motor domain and a long lever-arm domain. The 'lever-arm hypothesis' predicts that during the working stroke, the lever-arm domain tilts against the motor domain, which is bound to actin in a fixed orientation. To detect this working stroke in operation, we constructed fusion proteins by connecting Aequorea victoria green fluorescent protein and blue fluorescent protein to the amino and carboxyl termini of the motor domain of myosin II of Dictyostelium discoideum, a soil amoeba, and measured the fluorescence resonance energy transfer between the two fluorescent proteins. We show here that the carboxy-terminal fluorophore swings at the isomerization step of the ATP hydrolysis cycle, and then swings back at the subsequent step in which inorganic phosphate is released, thereby mimicking the swing of the lever arm. The swing at the phosphate-release step may correspond to the working stroke, and the swing at the isomerization step to the recovery stroke.
ISSN:0028-0836
1476-4687
DOI:10.1038/24640