BIOCHEMISTRY AND GENETICS OF MEMBRANE FUNCTIONS

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The long-tem goals of the proposed research are to provide better understanding of the binding protein-dependent transport systems. Recent development in my laboratory of a reconstitutable binding protein-dependent glutamine transport in isolated right-side-out- vesicles of E. coli should facilitate the study of the binding protein-membrane interaction by physico-chemical methods. Energetic study of glutamine transport in the vesicle system has yielded the significant finding that ATP is essential for the generation of the needed energy donor for transport; continued study proposed here is likely to lead to the ultimate identification of the elusive energy donor as well as the elucidation of its biosynthesis. The glutamine transport systems glnP has been cloned and analyzed by recombinant DNA techniques and the encoded products identified. Genetic and molecular genetic experiments are proposed to study the physiological effects of the glnP mutations, the physiological basis of the deleterious effect of the overproduction of the glnM protein as well as the nitrogen- regulation of the glnP system. The specific aims are: to identify the energy donor of the glutamine transport system in the right- side-out and inside-out vesicle systems using highly labeled 3H- ADP and 32P-PEP as tracers; to isolate, purify and characterize glutamine transport proteins; to study the genetic regulation of the glutamine transport system; to investigate the metabolic and physiological effects of glutamine transport defects on glutamine and proline utilization; to study the physiological and biochemical effects of the "killer" gene glnM; to study the structural and functional aspects of glutamine transport.