Structural Dynamics of Molecular Motors and the Ribosome

University Of Pennsylvania, Philadelphia PA

Investigators

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Abstract

Supplementary Application to NIGMS R35-R35GM118139, ?Structural Dynamics of Molecular Motors and the Ribosome?, Yale E. Goldman, PI Protein synthesis and active transport of vesicular cargoes are vital to development of all tissues and to the targeted delivery of organelles, proteins, and signaling molecules in eukaryotes. Accordingly, defects in protein expression and transport are linked to developmental, neurodegenerative, pigmentation, immunological, and other diseases. Knowing the detailed mechano-chemistry and structural dynamics of the ribosome and motor proteins is essential for understanding and interpreting their roles in the cell. We have developed a number of powerful new biophysical tools that reveal the modulation of structural dynamics and reaction kinetics of the protein synthesis elongation cycle and molecular motors under applied mechanical force, discriminate models of energy transduction and elucidate the essential rotational motions of conformational transitions of specific domains within the elongation factors and motor proteins. We will apply these unique tools to investigate the rhythm of protein synthesis in bacteria and eukaryotes and mechanisms that functionally modulate it and the divergent biochemical and mechanical properties of myosins-I, V, VI and X, and dynein isoforms. Understanding functional properties that have that have not yet been approached at the mechanistic detail is now possible. The R35 parent grant of this supplemental application combined and extended three NIGMS grants, and so has a number of aims. Our Aims in protein synthesis are to determine the mechanisms of modulation of protein synthesis rate of 1) downstream mRNA 2o structure and 2) upstream Shine-Delgarno (SD) sequences. Aim 3) is to develop a eukaryotic single molecule FRET platform for detailed study of peptide elongation in higher organisms. Aim 4) is to define how read-through of premature stop codons takes place and the mechanisms of small molecule enhancers of read-through, which are promising therapies in many diseases. For myosins I, V, VI and X, to 5) test the thermal search hypothesis, determine their flexibility and solve the mechanisms of their high directionality; 6) determine the mechanical force- dependence and the energetics of their mechanical stroke using an ultra-high-speed optical trap; 7) determine the dynamics of ATP association and ADP and Pi dissociation from the motors under force; 8) Determine the rotational motions of motor heads and lever arms that generate force and cargo translocation; 9) determine motor force and force regulation on intracellular cargos, and 10) determine how many kinesin motors are actively engaged on intracellular cargos and their spatial distributions. Overall, these studies will lead to a much more general view of the mechanisms and characteristics of the ribosome and molecular motors in vitro and in live cells leading to a more rigorous understanding of their functions in cell biology and disease. The present supplemental application is for purchase of replacement for a crucial preparative and analytical instrument used extensively throughout these studies, a fast protein liquid chromatography (FPLC) workstation.