title: Evidences of autoregulation of hfq expression in Sinorhizobium meliloti strain 2011.
abstract: Riboregulation comprises gene expression regulatory mechanisms that rely upon the activity of small non-coding RNAs (sRNAs) and in most cases RNA binding proteins. In γ-proteobacteria, the Sm-like protein Hfq is a key player in riboregulatory processes, because it promotes sRNA-mRNA interactions and influences mRNA polyadenylation or translation. In the α-proteobacterium Sinorhizobium meliloti, the large number of detected small RNA transcripts and the pleiotropic effects of hfq mutations lead to the hypothesis that riboregulatory mechanisms are important in this soil microorganism to adjust gene expression both in free-living conditions and as a nitrogen-fixing endosymbiont within legume root nodules. In this study, homology modeling of S. meliloti Hfq protein and cross-complementation experiments of S. meliloti and Escherichia coli mutants indicates that hfq ( Sm ) encodes an RNA chaperone that can be functionally exchanged by its homolog from E. coli. A transcriptional and translational analysis of S. meliloti hfq expression by means of lacZ reporter fusions strongly suggests that the S. meliloti Hfq protein autocontrols its expression at the translational level, a phenomenon that was evident in the natural host S. meliloti as well as in the heterologous host E. coli.
authors.affiliation: Programa Interacciones Biológicas, Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Bernal, Buenos Aires, Argentina.
authors.forename: Patricio
authors.initials: P
authors.lastname: Sobrero
authors.forename: Claudio
authors.initials: C
authors.lastname: Valverde
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry; D015964:Gene Expression Regulation, Bacterial; D006706:Homeostasis; D035001:Host Factor 1 Protein / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016962:Sinorhizobium meliloti / Q000235:genetics* / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; C087373:Hfq protein, E coli; D035001:Host Factor 1 Protein