conserved small RNA promotes silencing of the outer membrane protein YbfM

• Published in: Molecular microbiology Vol. 72; no. 3; pp. 566 - 577
• Main Authors: Rasmussen, Anders Aamann, Johansen, Jesper, Nielsen, Jesper S, Overgaard, Martin, Kallipolitis, Birgitte, Valentin-Hansen, Poul
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.05.2009; Blackwell Publishing Ltd; Blackwell
• Subjects: Bacteria; Bacterial Outer Membrane Proteins - genetics; Bacterial proteins; Binding sites; Biological and medical sciences; Cells; Escherichia coli - genetics; Escherichia coli Proteins - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Gene Silencing; Host Factor 1 Protein; Microbiology; Molecules; Mutation; Nucleic Acid Conformation; Oligonucleotide Array Sequence Analysis; Plasmids; Ribonucleic acid; RNA; RNA, Bacterial - genetics; RNA, Small Untranslated - genetics; Microbiology; External membrane; Membrane protein
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2009.06688.x

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.