O-LINKED PROTEIN GLYCOSYLATION IN BACTERIA

Protein glycosylation is a pivotal element of biological systems not only because it is one of the major post-translational modifications but also because it has significant effects on protein properties and functions. We have recently discovered, and par tially characterized, the first general O-linked protein glycosylation system to be found outside of eukaryotes. This occurs in the Gram negative human pathogen Neisseria gonorrhoeae, the aetiologic agent of gonorrhea. Biochemical characterization, geneti c manipulation and mass spectrometric analyses have led to the unambiguous identification of 8 of these glycoproteins. Remarkably, these proteins share few if gross features or functions (other than their targeting to the periplasm, the cellular compartme nt where glycan addition occurs). Additionally, all 8 proteins reside periplasmically and thus, this is the first example of a bacterial O-linked glycosylation system that targets intracellular proteins. Thus, this is the first bacterial system identified in which O-linked glycans play intracellular roles. Given its reduced complexity and amenability to genetic manipulation, this bacterial system provides a unique opportunity to address a number of important, and as yet unresolved, questions relevant to f unctional genomics and glycobiology. Here, we propose to focus on the following: 1) to characterize the N. gonorrohoeae glycoproteome, 2) to define the properties and acceptor site sequences of glycosylation targets, and 3) to characterize and identify re lated O-linked glycosylation systems in other Proteobacteria species. Not only can these studies provide new insights into host - parasite interactions and disease pathogenesis, they may help understand glycosylation processes in complex eukaryotic system s and provide knowledge that can be exploited in glycoengineering.