Speaker: Ludovic Sauguet - Department of Structural Biology & Chemistry, Institut Pasteur, Paris
Title: Uncovering the Molecular Mechanisms of Homologous Recombination in Archaea
Abstract: Genome maintenance in bacteria, archaea and eukaryotes critically depends on homologous recombination (HR), which enables the exchange of strands between homologous DNA molecules. During HR, a recombinase binds to ssDNA and forms a right-handed helical nucleoprotein filament, known as a presynaptic filament, which then searches dsDNA for homology. Upon encountering a homologous sequence, the presynaptic filament pairs with the complementarity strand, resulting in the displacement of the non-complementarity strand form the duplex to generate a displacement loop (D-loop) and promote DNA strand exchange. In all forms of life, DNA recombinases share a conserved ATPase domain for ATP binding. ATP is required for the self-association of protomers into an active nucleoprotein filament. In bacteria, HR relies on RecA while in eukaryotes it relies on Rad51/Dmc1. While Rad51 is the universal recombinase in eukaryotes, meiosis also requires Dmc1, which enables mismatch-tolerant inter-homologue recombination. In archaeal cells, the reaction of HR is performed by RadA. To uncover the specific features of archaeal recombinases, we determined the cryo-EM structures of RadA at distinct stages of the homologous recombination reaction: in its apo form, pre-synaptic, synaptic, and post-synaptic states. These structures highlight the evolutionary relationships between archaeal and eukaryotic recombinases.
I will also present a specific aspect of our project, which is the translation of fundamental biology into biotechnological applications through the engineering of archaeal polymerases for the development of cutting-edge nucleic acid technologies. More particularly, I will present our recent work on the discovery of a new family of enzymes that represent promising tools for the development of RNA printing technologies.
Invited by Sophie Zinn and Jean-Baptiste Charbonnier