Project 1. Regulation and Interactions among Molecular Motors, Yale E. Goldman The structural changes in molecular motors leading to motion and their relation to the biochemistry oftheir ATPase cycles and the mechanics of force generation are being elucidated using a combination ofsingle-molecule mechanical and spectroscopic approaches along with ensemble biochemistry and structuralbiology. But the mechanisms of their regulation and interaction with other molecular motors are still largelyunknown. In this project, techniques previously devised for investigation of the basic motility properties willbe applied to the mechanism of modulation of unconventional myosins, cytoplasmic dynein and its accessoryprotein complex, dynactin. Infrared optical trap, single-molecule fluorescence polarization, nanosecond time-resolved fluorescence anisotropy, electron microscopy and atomic force microscopy will be used incollaborative studies to determine the structural and functional consequences of Ca 2 interaction withcalmodulin light chains bound to myosin V. The same techniques will be applied to determine the basicmechanism of motility by cytoplasmic dynein and the facilitation of its motility by the accessory protein,dynactin. Unconventional myosins, dynein and kinesins interact with each other by direct binding, bycolocalization on individual vesicle cargoes, and or through interactions in the cytoplasm. They may carrytheir parmers to cellular destinations and then swap roles to become the cargo. By incorporating severalmolecular motor types into manipulatable cargoes in vitro, we will collaborate with other investigators in thisprogram and seek to understand these interactions. Complementary structural and mechanical studies willdelineate the supra-molecular interactions between molecular motor families. As cell proliferation, assembly,protein expression, motility, energy metabolism, defense, nourishment, and secretion all involve suchlocalized motor-driven complexes, the impact of understanding the mechanisms and control of targetedintracellular transport spreads across all of cell biology and biomedicine. Thus, detailed understanding of thefunction and interaction of these proteins have specific and broad-reaching implications in human disease andtreatment.
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