The long-term goal of this project is to describe in molecular terms the mechanism of binding protein-mediated membrane transport. All cells meet their environment at their membranes, and the membranes mediate many of the most important life processes, including nutrient transport. Yet little is known about the molecular structure or mechanism of any membrane protein. Two areas of research are proposed. First, site-directed mutagenesis of the gene (rbsB) for E. coli ribose binding protein will be performed to map the surface of the binding protein to determine the sites on the molecule which contact the membrane- bound transport complex and the chemotaxis receptor. This study will be based on a structure/function analysis of arabinose, galactose, and ribose binding proteins which suggested likely sites for the contact of the binding protein with the chemotaxis receptor. The second emphasis will be the overproduction, purification, and characterization of the membrane-associated components of the ribose transport operon. DNA sequence analyses have indicated there are three proteins in this complex. Once the proteins are purified, reconstitution of the complex in vitro will be pursued.