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A small RNA downregulates LamB maltoporin in Salmonella.
Mol Microbiol. 2007 Aug; 65(3):799-810.MM

Abstract

In Escherichia coli and Salmonella enterica, activation of sigma(E)-dependent envelope stress response leads to the abrupt decline in the synthesis of all major outer membrane proteins (OMPs). Recent studies found that two sigma(E)-controlled small RNAs (sRNAs), MicA and RybB, downregulate a number of OMPs. While RybB targets several different mRNAs, including ompC and ompD, MicA was up to date thought to act solely on ompA. Here we present evidence showing that MicA downregulates a second Salmonella OMP: LamB maltoporine. In strains overexpressing sigma(E), MicA accumulation leads to a significant decrease in LamB protein and mRNA levels, as well as a reduction in beta-galactosidase activity in a strain carrying a lamB-lacZ translational fusion. The latter findings provided the basis for a genetic screen that allowed isolating point mutations in the micA gene and in its sigma(E) promoter. All alleles obtained displayed their altered regulatory phenotype from their natural chromosomal location. LamB downregulation by MicA requires a functional Hfq protein. Besides this role, confined to sigma(E)-activated conditions, we show that loss of Hfq results in the accumulation of a lamB-malM dimeric precursor and of malM mRNA during unchallenged growth. This suggests that Hfq normally intervenes in a mechanism that uncouples expression of the malK-lamB-malM operon, causing the distal portion of the transcript to be clipped off and degraded.

Authors+Show Affiliations

Centre de Génétique Moléculaire, CNRS, 91198, Gif-sur-Yvette, France. bossi@cgm.cnrs-gif.frNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17608792

Citation

Bossi, Lionello, and Nara Figueroa-Bossi. "A Small RNA Downregulates LamB Maltoporin in Salmonella." Molecular Microbiology, vol. 65, no. 3, 2007, pp. 799-810.
Bossi L, Figueroa-Bossi N. A small RNA downregulates LamB maltoporin in Salmonella. Mol Microbiol. 2007;65(3):799-810.
Bossi, L., & Figueroa-Bossi, N. (2007). A small RNA downregulates LamB maltoporin in Salmonella. Molecular Microbiology, 65(3), 799-810.
Bossi L, Figueroa-Bossi N. A Small RNA Downregulates LamB Maltoporin in Salmonella. Mol Microbiol. 2007;65(3):799-810. PubMed PMID: 17608792.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A small RNA downregulates LamB maltoporin in Salmonella. AU - Bossi,Lionello, AU - Figueroa-Bossi,Nara, Y1 - 2007/07/03/ PY - 2007/7/5/pubmed PY - 2007/9/13/medline PY - 2007/7/5/entrez SP - 799 EP - 810 JF - Molecular microbiology JO - Mol Microbiol VL - 65 IS - 3 N2 - In Escherichia coli and Salmonella enterica, activation of sigma(E)-dependent envelope stress response leads to the abrupt decline in the synthesis of all major outer membrane proteins (OMPs). Recent studies found that two sigma(E)-controlled small RNAs (sRNAs), MicA and RybB, downregulate a number of OMPs. While RybB targets several different mRNAs, including ompC and ompD, MicA was up to date thought to act solely on ompA. Here we present evidence showing that MicA downregulates a second Salmonella OMP: LamB maltoporine. In strains overexpressing sigma(E), MicA accumulation leads to a significant decrease in LamB protein and mRNA levels, as well as a reduction in beta-galactosidase activity in a strain carrying a lamB-lacZ translational fusion. The latter findings provided the basis for a genetic screen that allowed isolating point mutations in the micA gene and in its sigma(E) promoter. All alleles obtained displayed their altered regulatory phenotype from their natural chromosomal location. LamB downregulation by MicA requires a functional Hfq protein. Besides this role, confined to sigma(E)-activated conditions, we show that loss of Hfq results in the accumulation of a lamB-malM dimeric precursor and of malM mRNA during unchallenged growth. This suggests that Hfq normally intervenes in a mechanism that uncouples expression of the malK-lamB-malM operon, causing the distal portion of the transcript to be clipped off and degraded. SN - 0950-382X UR - https://www.unboundmedicine.com/medline/citation/17608792/A_small_RNA_downregulates_LamB_maltoporin_in_Salmonella_ L2 - https://doi.org/10.1111/j.1365-2958.2007.05829.x DB - PRIME DP - Unbound Medicine ER -