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Auto-assemblage de la protéine bactérienne Hfq, actrice du métabolisme de l’ARN : rôle structural du domaine C-terminal.

Abstract : RNA-based regulations of gene expression allow quick and versatile responses from cells to changing environmental conditions. However, these regulations are often protein-mediated. The bacterial protein Hfq is one of the most studied RNA-based regulation partner. Found in various prokaryotes, it is an important virulence factor involved in many cellular processes. Hfq’s structure resembles a torus, formed by multiple β-sheets. Apart from this N-terminal region (NTR), a supplemental C-terminal region (CTR) with variable lengths and sequences may exist in some species. In E. coli, this specific region measures around 30 residues and is predicted as intrinsically disordered. Few studies focused on Hfq-CTR until recently.This work highlights new potential roles for Hfq-CTR. First, this region is able to self-interact and forms amyloid fibers which explains the self-assembled Hfq superstructures observed in vivo. Second, the protein can bind and efficiently condense DNA in vitro, strengthening the suggested role of Hfq in shaping the bacterial chromosome. This compaction is fully dependent on the CTR which is responsible for DNA bridging. Third, the CTR also gives to Hfq the ability to self-assemble on a lipid bilayer, explaining its membrane-localized fraction observed in vivo. The subsequent membrane reorganization might facilitate the release of RNAs in the extracellular medium, with potential implications on bacterial communication and interaction with surrounding cells and environment.
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Submitted on : Monday, December 11, 2017 - 11:27:14 PM
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  • HAL Id : tel-01661404, version 1

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Antoine, Baptiste, Malabirade. Auto-assemblage de la protéine bactérienne Hfq, actrice du métabolisme de l’ARN : rôle structural du domaine C-terminal.. Biochimie [q-bio.BM]. Université Paris-Saclay, 2017. Français. ⟨NNT : 2017SACLS234⟩. ⟨tel-01661404⟩

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