Orientation and mobility of actin in different intermediate states of the ATP hydrolysis cycle.
Using polarization fluorimetry, we have investigated conformational changes of FITC-phalloidin-labeled F-actin in ghost muscle fibers. These changes were induced by myosin subfragment-1 (S1) in the absence and 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 of orientation and mobility of actin monomers during the ATPase cycle. The most pronounced differences in orientation (~4 degrees ) and in mobility (~43%) of actin were found between the actomyosin states induced by MgADP and MgATP.
Khaimina
S S
SS
Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russia.
Wrzosek
A
A
Dabrowska
R
R
Borovikov
Yu S
YS
D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000205:Actomyosin / Q000737:chemistry / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D005454:Fluorescence Polarization; D006868:Hydrolysis; D009119:Muscle Contraction / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D015879:Myosin Subfragments / Q000737:chemistry / Q000378:metabolism; D010590:Phalloidine / Q000737:chemistry; D011817:Rabbits
D000199:Actins; D015879:Myosin Subfragments; D010590:Phalloidine; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000205:Actomyosin; D000251:Adenosine Triphosphatases; D016650:Fluorescein-5-isothiocyanate