title: Mechanism of blebbistatin inhibition of myosin II.
abstract: Blebbistatin is a recently discovered small molecule inhibitor showing high affinity and selectivity toward myosin II. Here we report a detailed investigation of its mechanism of inhibition. Blebbistatin does not compete with nucleotide binding to the skeletal muscle myosin subfragment-1. The inhibitor preferentially binds to the ATPase intermediate with ADP and phosphate bound at the active site, and it slows down phosphate release. Blebbistatin interferes neither with binding of myosin to actin nor with ATP-induced actomyosin dissociation. Instead, it blocks the myosin heads in a products complex with low actin affinity. Blind docking molecular simulations indicate that the productive blebbistatin-binding site of the myosin head is within the aqueous cavity between the nucleotide pocket and the cleft of the actin-binding interface. The property that blebbistatin blocks myosin II in an actin-detached state makes the compound useful both in muscle physiology and in exploring the cellular function of cytoplasmic myosin II isoforms, whereas the stabilization of a specific myosin intermediate confers a great potential in structural studies.
authors.affiliation: Laboratory of Molecular Cardiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-1762, USA.
authors.forename: Mihály
authors.initials: M
authors.lastname: Kovács
authors.forename: Judit
authors.initials: J
authors.lastname: Tóth
authors.forename: Csaba
authors.initials: C
authors.lastname: Hetényi
authors.forename: András
authors.initials: A
authors.lastname: Málnási-Csizmadia
authors.forename: James R
authors.initials: JR
authors.lastname: Sellers
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D006576:Heterocyclic Compounds, 4 or More Rings / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D008958:Models, Molecular; D024462:Myosin Type II / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011817:Rabbits
chemical_list: D006576:Heterocyclic Compounds, 4 or More Rings; C472645:blebbistatin; D000244:Adenosine Diphosphate; D000251:Adenosine Triphosphatases; D024462:Myosin Type II