Grant: Operating Grant

Pathogenic E. coli strains cause life-threatening diseases manifesting by recent outbreaks in Canada and worldwide. The ability of these pathogenic bacteria to establish infection in humans and animals depends on combined function of defined set of specific pathogenic factors called "effectors" that are delivered inside the host cell by a specialized syringe-like multiprotein complex called type 3 secretion system. The largest family in E. coli effector arsenal constitutes so-called NleG effectors, of which there are 14 members in enterohamerrhagic E. coli (EHEC) strains. We have recently characterised a conserved part of NleG effectors to share the structural fold and functionality with protein ubiquitin ligases also known as E3 enzymes. This diverse class of proteins perform a critical step in a process termed 'ubiquitination'; the addition of a small protein 'ubiquitin' to lysines of a target protein. Ubiquitination is highly conserved across all eukaryotes and is critical in protein turnover, protein localization and cell signaling processes. The E3 ligase are major determinants of specificity for ubiquitination process. Although our preliminary data linked the function of NleG effectors to host ubiquitination, their function remains unknown. In the current proposal we aim to identify the host targets of NleG effectors and establish their role in E. coli pathogenesis process using combined structural, biochemical and in vivo analysis. This will significantly advance our understanding of molecular aspects of infection by this important bacterial pathogen and open up the possibility to design novel antibacterial therapies.