Unique post-translational modifications in a prokaryotic model system

Post-translational modifications (PTMs) are covalent processing events that modify the properties of protein by proteolytic cleavage or by addition of a modifying group to one or more amino acids. They modulate biological processes by influencing protein activity, localization, turnover, and interactions with other proteins. Because many PTMs are only stumbled upon late in studies of various systems, the full extent and functional importance of PTMs protein have likely yet to be realized. PTM biology has entered a new era that coincides with 1) the acquisition of genome sequences for multiple organisms, 2) an increased appreciation for how they contribute to normal and disease physiology and 3) significant advances in mass spectrometric technologies. Here we propose to study covalent modifications of the Neisseria gonorrhoeae Type IV pilus (Tfp) colonization factor with the novel moieties phosphoethanolamine and phosphocholine as well as a unique disaccharide. The use of this simple prokaryotic model syst em is predicated on its amenability to genetic manipulation and the ease with which large amounts of protein can be isolated as well as its clear relevance of Tfp to human disease caused by N. gonorrhoeae and N. meningitidis and other important human path ogens. Furthermore, the knowledge gained will undoubtedly yield insights into basic aspects of Tfp biology including organelle biogenesis, membrane translocation events and molecular basis for the structure to act as a molecular motor. Finally, there appe ar to be remarkable similarities between N. gonorrhoeae Tfp glycosylation, N-linked glycosylation in Campylobacter jejuni, O-antigen synthesis in Gram negatives and the initial steps in glycan incorporation into eukaryotic glycoproteins. Thus, these studi es have a strong potential to enrich our understanding of fundamental biological processes.