An antisense RNA that governs the expression kinetics of a multifunctional virulence gene

Mol Microbiol. 2010 May;76(4):1020-33. doi: 10.1111/j.1365-2958.2010.07161.x. Epub 2010 Apr 14.

Abstract

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 diminished 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / genetics*
  • Amino Acid Sequence
  • Animals
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Base Sequence
  • Cation Transport Proteins / genetics*
  • Gene Expression Regulation, Bacterial*
  • Mice
  • Molecular Sequence Data
  • Promoter Regions, Genetic
  • RNA Stability
  • RNA, Antisense / genetics
  • RNA, Antisense / metabolism*
  • Salmonella typhimurium / genetics*
  • Salmonella typhimurium / pathogenicity
  • Virulence / genetics

Substances

  • Bacterial Proteins
  • Cation Transport Proteins
  • RNA, Antisense
  • PhoP protein, Bacteria
  • Adenosine Triphosphatases
  • MgtB protein, Salmonella typhimurium
  • MgtC protein, Salmonella typhimurium