Development of photo-driven motor proteins using phtochromic molecules

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ATP driven-motor proteins transduce chemical energy generated from ATP hydrolysis into the physical motion energy with the mechanical system like cam-shaft. It is expected that introduction of artificial energy input device into the energy transducing site of motor protein, enable the driving or regulating of motor proteins without ATP. In the present study, photochromic molecules which change their conformation reversibly with high response due to the isomerization by ultraviolet (UV) and visible light (VIS) irradiation, have been utilized as energy input device. Especially azobenzene and spiropyran derivatives, which change their characteristics dramatically on isomerization by UV-VIS light irradiation, might work effectively.In this study, several kinds of azobenzene and spiropyran derivatives, which can bind to cysteine side chain covalently, have been synthesized. And several motor protein mutants, which have one reactive cysteine at the specific site, have been also prepared. It has been demonstrated that for skeletal muscle myosin motor domain, the localized conformational changes resulting from isomerization on azobenzene derivative cross-linking of reactive cysteine residues, SH1 and SH2 induced swing in the lever arm portion. It was shown that the incorporated photochromic group acts as a mechanical energy input in a motor protein. The new technique using photochromic molecules may be applicable to other energy transducing and regulatory proteins.