title: A conserved small RNA promotes silencing of the outer membrane protein YbfM.
abstract: In the past few years an increasing number of small non-coding RNAs (sRNAs) in enterobacteria have been found to negatively regulate the expression of outer membrane proteins (OMPs) at the post-transcriptional level. These RNAs act under various growth and stress conditions, suggesting that one important physiological role of regulatory RNA molecules in Gram-negative bacteria is to modulate the cell surface and/or to prevent accumulation of OMPs in the envelope. Here, we extend the OMP-sRNA network by showing that the expression of the OMP YbfM is silenced by a conserved sRNA, designated MicM (also known as RybC/SroB). The regulation is strictly dependent on the RNA chaperone Hfq, and mutational analysis indicates that MicM sequesters the ribosome binding site of ybfM mRNA by an antisense mechanism. Furthermore, we provide evidence that Hfq strongly enhances the on-rate of duplex formation between MicM and its target RNA in vitro, supporting the idea that a major cellular role of the RNA chaperone is to act as a catalyst in RNA-RNA duplex formation.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, Odense M, Denmark.
authors.forename: Anders Aamann
authors.initials: AA
authors.lastname: Rasmussen
authors.forename: Jesper
authors.initials: J
authors.lastname: Johansen
authors.forename: Jesper S
authors.initials: JS
authors.lastname: Nielsen
authors.forename: Martin
authors.initials: M
authors.lastname: Overgaard
authors.forename: Birgitte
authors.initials: B
authors.lastname: Kallipolitis
authors.forename: Poul
authors.initials: P
authors.lastname: Valentin-Hansen
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D020868:Gene Silencing; D035001:Host Factor 1 Protein; D009154:Mutation; D009690:Nucleic Acid Conformation; D020411:Oligonucleotide Array Sequence Analysis; D010957:Plasmids; D012329:RNA, Bacterial / Q000235:genetics; D058727:RNA, Small Untranslated / Q000235:genetics*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; C087373:Hfq protein, E coli; D035001:Host Factor 1 Protein; D012329:RNA, Bacterial; D058727:RNA, Small Untranslated