Regulation of Rot expression in Staphylococcus aureus.
Repressor of toxins (Rot) is known to be a global regulator of virulence gene expression in Staphylococcus aureus. The function of Rot, but not the transcription of rot, is regulated by the staphylococcal accessory gene regulator (Agr) quorum-sensing system. In addition, the alternative sigma factor (sigma(B)) has a repressive effect on rot expression during the postexponential phase of growth. The transcriptional profiles of Rot in sigma(B)-positive and sigma(B)-negative strains in the postexponential and stationary phases of growth were compared. An upregulation of rot expression was observed during the stationary phase of growth, and this upregulation occurred in a sigma(B)-dependent manner. The effects of other staphylococcal transcriptional factors were also investigated. Electrophoretic mobility shift assays revealed that proteins present in staphylococcal lysates retarded the mobility of the rot promoter fragment and that the effect was reduced, but not eliminated, with lysates from strains lacking a functional SarS protein. A modest upregulation of rot expression was also observed in sarS-negative strains. Affinity purification of proteins binding to the rot promoter fragment, followed by N-terminal protein sequencing, identified the SarA and SarR proteins. Primer extension analysis of the rot promoter revealed a number of discreet products. However, these RNA species were not associated with identifiable promoter activity and likely represented RNA breakdown products. Loss of Rot function during the postexponential phase of growth likely involves degradation of the rot mRNA but not the inhibition of rot transcription.
Hsieh
Hsin-Yeh
HY
Bond Life Sciences Center 471E, 1201 Rollins Street, University of Missouri, Columbia, MO 65211-7310, USA.
Tseng
Ching Wen
CW
Stewart
George C
GC
D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D024202:Electrophoretic Mobility Shift Assay; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics / Q000502:physiology*; D016254:Mutagenesis, Insertional; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012097:Repressor Proteins / Q000096:biosynthesis*; D012808:Sigma Factor / Q000235:genetics / Q000502:physiology; D013211:Staphylococcus aureus / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000302:isolation & purification / Q000378:metabolism
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; C492107:SarA protein, Staphylococcus aureus; C476149:SarS protein, Staphylococcus aureus; C079011:SigB protein, Bacteria; D012808:Sigma Factor; D014157:Transcription Factors; C408643:rot protein, Staphylococcus aureus