title: New insight into the structure and function of Hfq C-terminus.
abstract: Accumulating evidence indicates that RNA metabolism components assemble into supramolecular cellular structures to mediate functional compartmentalization within the cytoplasmic membrane of the bacterial cell. This cellular compartmentalization could play important roles in the processes of RNA degradation and maturation. These components include Hfq, the RNA chaperone protein, which is involved in the post-transcriptional control of protein synthesis mainly by the virtue of its interactions with several small regulatory ncRNAs (sRNA). The Escherichia coli Hfq is structurally organized into two domains. An N-terminal domain that folds as strongly bent β-sheets within individual protomers to assemble into a typical toroidal hexameric ring. A C-terminal flexible domain that encompasses approximately one-third of the protein seems intrinsically unstructured. RNA-binding function of Hfq mainly lies within its N-terminal core, whereas the function of the flexible domain remains controversial and largely unknown. In the present study, we demonstrate that the Hfq-C-terminal region (CTR) has an intrinsic property to self-assemble into long amyloid-like fibrillar structures in vitro. We show that normal localization of Hfq within membrane-associated coiled structures in vivo requires this C-terminal domain. This finding establishes for the first time a function for the hitherto puzzling CTR, with a plausible central role in RNA transactions.
authors.affiliation: *Laboratoire Léon Brillouin, CEA-Centre de Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Fortas
authors.affiliation: ‡Department of Physics and Chemistry, University of Palermo, Viale delle Scienze, Ed. 18, 90128 Palermo, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Piccirilli
authors.affiliation: *Laboratoire Léon Brillouin, CEA-Centre de Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Malabirade
authors.affiliation: ‡Department of Physics and Chemistry, University of Palermo, Viale delle Scienze, Ed. 18, 90128 Palermo, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Militello
authors.affiliation: §Institut Curie, Centre de Recherche, Campus Universitaire d'Orsay, bât 112, 91405 Orsay Cedex, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Trépout
authors.affiliation: §Institut Curie, Centre de Recherche, Campus Universitaire d'Orsay, bât 112, 91405 Orsay Cedex, France.
authors.forename: Sergio
authors.initials: S
authors.lastname: Marco
authors.affiliation: ¶¶Department of Molecular Biology and Biophysics, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06032, U.S.A.
authors.forename: Aziz
authors.initials: A
authors.lastname: Taghbalout
authors.affiliation: *Laboratoire Léon Brillouin, CEA-Centre de Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Arluison
mesh_terms: D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D035001:Host Factor 1 Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D012329:RNA, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; C087373:Hfq protein, E coli; D035001:Host Factor 1 Protein; D012329:RNA, Bacterial