Photoregulation of Molecular Motors using Photochromic Nucleotide Analogue

Abstract

Photochromic molecules can be interconverted between two quite different states with different spectroscopic properties using two different wavelength lights. Therefore, the photochromic molecules have received much attention because of their potential application to optical switches, bio-nanodevices, and molecular machines. Azobenzene is a typical photochromic molecule that undergoes rapid and reversible isomerization between the cis and trans-isomer in response to ultraviolet (UV) and visible (VIS) light irradiation, respectively. Previously, we have succeeded to control microtubule dependent ATPase activity of kinesin in which functional region was modified with azobenzene derivative photo-reversibly. Moreover, we synthesized photochromic ATP analogue PABITP composed of azobenzene to regulate ATP driven motor proteins. PABITP induced microtubule gliding for kinesin and the gliding velocity altered correlating to cis-trans photo-isomerization of azobenzene moiety. For myosin, although PABITP was hydrolyzed as a substrate for ATPase and induced conformational change of myosin motor domain, PABITP did not drive actin gliding. In this study, we designed and synthesized a novel photochromic nucleotide analogue composed of photochromic fulgimide moiety in order to regulate ATP driven molecular motors, myosin and kinesin photo-reversibly. The photochromic ATP analogue, Fulgimide-Tri-Phosphate (FITP) exhibited ring-opening and ring-closing photo-isomerization upon UV and VIS light irradiations. FITP worked as a substrate of skeletal muscle myosin and induced dissociation of acto-myosin in a different manner upon UV and VIS light irradiations. We also examined the interaction of FITP with kinesin and its effect for the polymerization of tubulin to microtubules.