Insights into the regulation of small RNA expression: SarA represses the expression of two sRNAs in Staphylococcus aureus.
The opportunistic pathogen Staphylococcus aureus expresses transcription factors (TFs) and regulatory small RNAs (sRNAs) which are essential for bacterial adaptation and infectivity. Until recently, the study of S. aureus sRNA gene expression regulation was under investigated, but it is now an expanding field. Here we address the regulation of Srn_3610_SprC sRNA, an attenuator of S. aureus virulence. We demonstrate that SarA TF represses srn_3610_sprC transcription. DNase I footprinting and deletion analyses show that the SarA binding site on srn_3610_sprC belongs to an essential 22 bp DNA region. Comparative analysis also revealed another possible site, this time in the srn_9340 promoter. SarA specifically binds these two sRNA promoters with high affinity in vitro and also represses their transcription in vivo Chromatin immunoprecipitation (ChIP) assays confirmed SarA attachment to both promoters. ChIP and electrophoretic mobility shift assays targeting σARNA polymerase subunit or using bacterial RNA polymerase holoenzyme suggested that SarA and the σAbind srn_3610_sprC and srn_9340 promoters in a mutually exclusive way. Beyond the mechanistic study of SarA repression of these two sRNAs, this work also suggests that some S. aureus sRNAs belong to the same regulon and act jointly in responding to environmental changes.
Inserm U835, Biochimie Pharmaceutique, University of Rennes 1, 35000 Rennes, France.
Tony
T
Mauro
Inserm U835, Biochimie Pharmaceutique, University of Rennes 1, 35000 Rennes, France astrid.rouillon@univ-rennes1.fr.
Astrid
A
Rouillon
Inserm U835, Biochimie Pharmaceutique, University of Rennes 1, 35000 Rennes, France brice.felden@univ-rennes1.fr.
Brice
B
Felden
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D013211:Staphylococcus aureus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D012329:RNA, Bacterial; C492107:SarA protein, Staphylococcus aureus; D012321:DNA-Directed RNA Polymerases