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Substitutions E240K and R244G in tropomyosin have similar effects on actin-myosin interaction during ATPase cycleтезисы доклада
- Авторы: Simonyan AO, Sirenko VV, Robaszkiewicz K., Boris D., Moraczewska J., Krutetskaya Z., Borovikov YS
- Сборник: Journal of Muscle Research and Cell Motility
- Серия: 45th European Muscle Conference in Montpellier, France
- Том: 38
- Тезисы
- Год издания: 2017
- Место издания: SPRINGER 22 RUE DE PALESTRO, PARIS, FRANCE, 75002
- Первая страница: S10.P5-157
- DOI: 10.1007/s10974-016-9457-1
- Аннотация: Using polarized photometry we have studied the effects of two amino acid replacements, E240K and R244G, in afast-tropomyosin (Tpm1.1) on the position of Tpm1.1 on actin filaments and the spatial arrangement of actin monomers and myosin heads at the various mimicked stages of the ATPase cycle in the absence of troponin and calcium. E240K and R244G are located in the C-terminal, seventh actin-binding period, in f and b positions of the coiled coil heptapeptide repeat. Actin, Tpm1.1, and myosin subfragment-1 (S1) were fluorescently labeled: 1,5-IAEDANS was attached to actin and S1, 5-IAFwas bound to Tpm1.1. The labeled proteins were incorporated in ghost muscle fibers and the changes in polarized fluorescence during the ATPase cycle have been measured. The data obtained suggest that the E240K and R244G tropomyosins occupy centreshifted position on the thin filaments, but they inhibit the ability of myosin heads to switch ON the actin monomers during different simulated stages of ATPase cycle and to form the weak-binding state with F-actin. The lack of actin activation and ‘freezing’ myosin heads in a strongly-bound state are the reason of reduced activity of the actomyosin Mg-ATPase observed in solution in the presence of the mutant tropomyosins. These effects suggest that similar structural changes might be the molecular basis of muscle weakness in congenital fiber type disproportion caused by substitutions E241K and R245G in Tpm3.12. The work was supported by the Russian Foundation for Basic Research (Project No.14-04-00454) and statutory funds to Kazimierz Wielki University.
- Добавил в систему: Боровиков Юрий Сергеевич