Searching for small σB-regulated genes in Staphylococcus aureus.
In recent years, small RNAs (sRNAs) have been identified as important regulators of gene expression in bacteria. Most sRNAs are encoded from intergenic regions and are only expressed under highly specific growth conditions. In Staphylococcus aureus, the alternative sigma factor, σ(B), is known to contribute to the overall stress response, antibiotic resistance, and virulence. The σ(B) regulon in S. aureus is well described and comprises approximately 200 annotated genes, including several genes encoding virulence factors. In the present study, we have identified three novel σ(B)-dependent transcripts encoded from genomic regions previously annotated as intergenic. All three transcripts, named SbrA, SbrB, and SbrC, are highly conserved in S. aureus, and we confirmed their presence in four different isolates (SH1000, Newman, COL, and UAMS-1). Curiously, two of these genes (sbrA and sbrB) were found to contain open reading frames encoding small, highly basic peptides that are conserved among Staphylococci. The third transcript (SbrC) did not contain any likely open reading frame and thus constitute a genuine non-coding sRNA. The functions of these genes are currently unknown but are likely to be important for the σ(B)-mediated response of S. aureus to adverse conditions.
Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
Jesper S
JS
Nielsen
Mie H G
MH
Christiansen
Mette
M
Bonde
Sanne
S
Gottschalk
Dorte
D
Frees
Line E
LE
Thomsen
Birgitte H
BH
Kallipolitis
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D019295:Computational Biology; D021901:DNA, Intergenic / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D035001:Host Factor 1 Protein / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D012329:RNA, Bacterial / Q000235:genetics*; D058727:RNA, Small Untranslated / Q000235:genetics; D016415:Sequence Alignment; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000235:genetics* / Q000378:metabolism*; D024363:Transcription Initiation Site
D001426:Bacterial Proteins; D021901:DNA, Intergenic; D035001:Host Factor 1 Protein; D012329:RNA, Bacterial; D058727:RNA, Small Untranslated; D012808:Sigma Factor