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School of Biological and Chemical Sciences

Salomé Bodet Lefèvre

PhD student



Project title: Structural studies of the DNA processing protein TraI and its interactions with DNA and TraM

Summary: Bacterial conjugation is the process through which plasmid DNA is transferred from one bacterial cell to another.  It is also the mechanism through which antibiotic resistance, a rising global health crisis, is spread. Conjugation requires cell-to-cell contact, and involves transferring a single strand of plasmid DNA to the recipient cell through the type IV secretion system. Before this can be done, the plasmid DNA is processed by a multi protein-DNA complex called the relaxosome. The relaxase, called TraI in the F family of plasmids, is the main protein of this complex. It has the dual function of making a single strand nick in the plasmid DNA at a specific site in a region called the origin of transfer (OriT), and of acting as a helicase to unwind the plasmid’s two DNA strands. Using a structural approach, we aim to study TraI, its covalent binding to nicked DNA, the different states it goes through, and its possible interactions with the accessory protein TraM.