Plasma membrane glycosphingolipid signaling: a turning point.

Plasma membrane interaction is highly recognized as an essential step to start the intracellular events in response to extracellular stimuli. The ways in which these interactions take place are less clear and detailed. Over the last decade my research has focused on developing the understanding of the glycosphingolipids-protein interaction that occurs at cell surface. By using chemical synthesis and biochemical approaches we have characterized some fundamental interactions that are key events both in the immune response and in the maintenance of neuronal homeostasis. In particular, for the first time it has been demonstrated that a glycolipid, present on the outer side of the membrane, the long-chain lactosylceramide, is able to directly modulate a cytosolic protein. But the real conceptual change was the demonstration that the GM1 oligosaccharide chain is able, alone, to replicate numerous functions of GM1 ganglioside and to directly interact with plasma membrane receptors by activating specific cellular signaling. In this conceptual shift, the development and application of multidisciplinary techniques in the field of biochemistry, from chemical synthesis to bioinformatic analysis, as well as discussions with several national and international colleagues have played a key role.

Expanding our understanding of the role of microbial glycoproteomes through high-throughput mass spectrometry approaches.

Protein glycosylation is increasingly recognised as an essential requirement for effective microbial infections. Within microbial pathogen's protein glycosylation is used for both defensive and offensive purposes; enabling pathogens to fortify themselves against the host immune response or to disarm the host's ability to resist infection. Although microbial protein glycosylation systems have been recognised for nearly two decades only recently has the true extend of protein glycosylation within microbes begun to be appreciated. A key enabler for this conceptual shift has been the development and application of modern approaches for the characterisation of glycosylation. Over the last decade my research has focused on the development of proteomic tools to probe microbial glycosylation. By developing workflows for glycopeptide enrichment and identification we have demostrated that it is now possible to characterise the glycoproteomes of microbial species in a truely high-throughput manner. Using these high-throughput approaches we have shown a number of bacterial species modify multiple proteins including members of the Campylobacter genus and the pathogens A. baumannii, R. solanacearum and B. cenocepacia. These studies have established that bacterial glycosylation is widespread, that glycan microheterogeneity is common place and that an extensive array of glycans are used to decorate protein compared to Eukaryotic glycosylation systems. Excitingly these approaches developed to characterise O- and N-linked bacterial glycosylation systems are equally amenable to studying newly discovered forms of microbial glycosylation such as Arginine glycosylation as well as glycosylation within the parasitic eukaryotic organisms T. gondii and P. falciparum. This work demonstrates that MS approaches can now be considered an indispensable tool for the elucidation and tracking of microbial glycosylation events.