CHARACTERIZATION OF MEMBRANE-BINDING BY FTSY, THE PROKARYOTE SRP RECEPTOR

Abstract

<p>The signal recognition particle pathway cotranslationally targets polytopic proteins to the inner membrane of Escherichia coli. FtsY is the receptor that is recognized by the ribosome-nascent chain-bound signal recognition particle in the bacterial targeting reaction. At the outset of this work a major unresolved issue, and current issue of some contention is the mechanism of Fts Y assembly on the E. coli inner membrane. To clarify the nature of this process, this thesis describes the region of FtsY that binds the membrane and a site-specific cleavage event that defines this region upon membrane binding. The involvement of a specific lipid, phosphatidylethanolamine and an as-yet unidentified inner membrane protein in FtsY membrane targeting are also addressed. With this understanding of the mechanisms ofFtsY membrane assembly in E. coli, additional investigations demonstrate divergent species-specific interactions with the membrane for FtsY homologues from Bacillus subtilis and Streptomyces coelicolor. Finally, the unique amino- erminal region was determined to be essential for the function of FtsY in E. coli.</p>