Transcriptional regulation of Staphylococcus aureus biofilm-associated genes in a brpR mutant compared to wild type

Staphylococcus aureus (S. aureus) causes a wide range of diseases, including bloodstream and skin infections. Drug resistant S. aureus strains have become very common. A novel antimicrobial drug developed at the University of Wisconsin-La Crosse named SK-03-92 may help combat the antimicrobial resistance issue. SK-03-92 treatment downregulates transcription of the brpR (biofilm regulating protein regulator) and brpS (biofilm regulating protein sensor) genes in S. aureus. In this study, the involvement of BrpR in regulating other genes was assessed by comparing transcriptional changes in a brpR mutant strain to the S. aureus unmutated parent strain via RNA sequencing. Bioinformatic analysis was performed on the data generated by the RNA sequencing results, including the use of Cytoscape, to assess what biochemical pathways might be involved. From these analyses, 459 genes were identified that had significant differences in transcript abundance when comparing the brpR mutant to wild type. Nine genes (citC, metE, pdhA, pdhC, bacA, mraY, mw1254, mw1287, and cap8G) were chosen for quantitative reverse transcription polymerase chain reaction analysis to confirm transcriptional differences between the brpR mutant and parent strain. Further, an enzymatic assay targeting NADH production from the pyruvate dehydrogenase complex was performed to support RNA sequencing and bioinformatic analysis results of the pdhA and pdhC genes. Overall, a better understanding of how BrpR regulates biofilm formation and late-stage competency were elucidated.