Repression of hla by rot is dependent on sae in Staphylococcus aureus.
The regulatory locus sae is a two-component system in Staphylococcus aureus that regulates many important virulence factors, including alpha-toxin (encoded by hla) at the transcriptional level. The SarA homologs Rot and SarT were previously shown to be repressors of hla in selected S. aureus backgrounds. To delineate the interaction of rot and sae and the contribution of sarT to hla expression, an assortment of rot and sae isogenic single mutants, a rot sae double mutant, and a rot sae sarT markerless triple mutant were constructed from wild-type strain COL. Using Northern blot analysis and transcriptional reporter gene green fluorescent protein, fusion, and phenotypic assays, we found that the repression of hla by rot is dependent on sae. A rot sae sarT triple mutant was not able to rescue the hla defect of the rot sae double mutant. Among the three sae promoters, the distal sae P3 promoter is the strongest in vitro. Interestingly, the sae P3 promoter activities correlate with hla expression in rot, rot sae, and rot sae sarT mutants of COL. Transcriptional study has also shown that rot repressed sae, especially at the sae P3 promoter. Collectively, our data implicated the importance of sae in the rot-mediated repression of hla in S. aureus.
Li
Dongmei
D
Department of Microbiology and Immunology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
Cheung
Ambrose
A
D000818:Animals; D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics*; D015152:Blotting, Northern; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D006460:Hemolysin Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000235:genetics / Q000502:physiology*; D012329:RNA, Bacterial / Q000032:analysis; D012097:Repressor Proteins / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D006460:Hemolysin Proteins; D012329:RNA, Bacterial; D012097:Repressor Proteins; C433805:SaeR protein, Staphylococcus aureus; C433204:SarH3 protein, Staphylococcus aureus; D014157:Transcription Factors; C485184:enhanced green fluorescent protein; C408643:rot protein, Staphylococcus aureus; C021091:staphylococcal alpha-toxin; D049452:Green Fluorescent Proteins; D011494:Protein Kinases; C527351:SaeS protein, Staphylococcus aureus