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An antisense RNA that governs the expression kinetics of a multifunctional virulence gene
Author(s) -
Lee EunJin,
Groisman Eduardo A.
Publication year - 2010
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2010.07161.x
Subject(s) - biology , rnase p , antisense rna , transcription (linguistics) , rna , virulence , sense (electronics) , ribonuclease iii , rnase h , gene , gene expression , messenger rna , salmonella enterica , microbiology and biotechnology , genetics , rna interference , escherichia coli , linguistics , philosophy , electrical engineering , engineering
Summary Genome‐wide transcriptome analyses of several bacterial species have recently uncovered a hitherto unappreciated amount of antisense transcription. However, the physiological role, regulation and significance of such antisense transcripts are presently unclear. We now report the identification of a cis ‐encoded 1.2 kb long antisense RNA – termed AmgR – that is complementary to the mgtC portion of the mgtCBR polycistronic message from Salmonella enterica . The mgtCBR mRNA specifies the MgtC protein, which is necessary for survival within macrophages, virulence in mice and growth in low Mg 2+ ; the Mg 2+ transporter MgtB with no apparent role in virulence; and the membrane peptide MgtR mediating MgtC degradation. Expression of AmgR dimished both MgtC and MgtB protein levels in a process requiring RNase E but independent of RNase III, the RNA chaperone Hfq, and the regulatory peptide MgtR. Inactivation of the chromosomal amgR promoter increased MgtC and MgtB protein levels and enhanced Salmonella virulence. Surprisingly, AmgR transcription is governed by the regulatory protein PhoP, which also directs transcription of the sense mgtCBR mRNA. AmgR may function as a timing device that alters MgtC and MgtB levels after the onset of PhoP‐inducing conditions.