DNA processing during conjugative transfer of ICEs from Firmicutes

Nicols Soler

Université de Lorraine, Dynamic, Nancy

Bacterial genomes mainly evolve through horizontal gene exchanges. They nobably enable the spreading of virulence or antibiotic resistance genes. A major mechanism for these genetic exchanges is bacterial conjugation, which requires cell-cell contact. It is mediated by mobile genetic elements such as conjugative plasmids and integrative and conjugative elements (ICEs). The latter are widespread in bacterial genomes, however, their molecular mechanism of transfer is still poorly described to date. Our studies aim to understand how DNA is processed before being addressed to the conjugation pore, at the early steps of bacterial conjugation in Firmicutes. These DNA processing steps are orchestrated by relaxases, which are sequence-specific transesterases encoded by ICEs. Especially, we aim to characterize the biochemical and structural features of a widespread family of relaxases, the MOBT relaxases, found in ICEs of the Tn916/ICESt3 superfamily.

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