title: Effect of nucleotides on the orientation and mobility of myosin subfragment-1 in ghost muscle fiber.
abstract: Using polarization fluorimetry, the orientation and mobility of 1,5-IAEDANS specifically bound to Cys707 of myosin subfragment-1 (S1) were studied in ghost muscle tropomyosin-containing fibers in the absence and in the presence of MgADP, MgAMP-PNP, MgATPgammaS, or MgATP. Modeling of various intermediate states was accompanied by discrete changes in actomyosin orientation and mobility of fluorescent dye dipoles. This suggests multistep changes in the structural state of the myosin head during the ATPase cycle. Maximal differences in the probe orientation by 4 degrees and its mobility by 30% were found between actomyosin states in the presence of MgADP and MgATP. It is suggested that interaction of S1 with F-actin induces nucleotide-dependent rotation of the whole motor domain of the myosin head or only the dye-binding site and also change in the head mobility.
authors.affiliation: Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russia.
authors.forename: O E
authors.initials: OE
authors.lastname: Pronina
authors.forename: A
authors.initials: A
authors.lastname: Wrzosek
authors.forename: R
authors.initials: R
authors.lastname: Dabrowska
authors.forename: Yu S
authors.initials: YS
authors.lastname: Borovikov
mesh_terms: D000199:Actins / Q000378:metabolism; D000205:Actomyosin / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D005454:Fluorescence Polarization; D018485:Muscle Fibers, Skeletal / Q000187:drug effects* / Q000648:ultrastructure; D015879:Myosin Subfragments / Q000737:chemistry* / Q000187:drug effects / Q000648:ultrastructure; D009711:Nucleotides / Q000494:pharmacology*; D010590:Phalloidine / Q000737:chemistry; D011487:Protein Conformation; D014335:Tropomyosin / Q000378:metabolism
chemical_list: D000199:Actins; D015879:Myosin Subfragments; D009711:Nucleotides; D014335:Tropomyosin; D010590:Phalloidine; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000205:Actomyosin; D016650:Fluorescein-5-isothiocyanate