A Novel LysR-Type Global Regulator RpvA Controls Persister Formation and Virulence in Staphylococcus aureus

Abstract

Staphylococcus aureus is the leading cause of wound and nosocomial infections. Persister formation and virulence factors play crucial roles during S. aureus infection. However, the mechanisms of persister formation and its relationship to virulence in S. aureus are poorly understood. In this study, we screened a transposon mutant library and identified a LysR-type global transcriptional regulator NWMN_0037, which we called RpvA, for regulator of persistence and virulence, whose mutation leads to higher susceptibility to antibiotics ampicillin and norfloxacin and various stresses including oxidative stress, heat, and starvation in late exponential and early stationary phase. Interestingly, the rpvA mutant was highly attenuated for virulence compared with the parent S. aureus Newman strain as shown by a much higher lethal dose, reduced ability to survive in macrophages and to form abscess in the mouse model. Transcriptional profiling and metabolomic analysis revealed that RpvA could repress multiple genes including gapR, gapA, tpi, pgm, eno, glpD, and acs expression and enhance production of numerous intermediate metabolites including dihydroxyacetone phosphate, 2-phosphoglycerate, acetyl-CoA, glycerol 3-phosphate, L-glutamate in the cells. The differentially expressed genes and altered production of metabolites are distributed in global metabolism including carbohydrate metabolism, amino acid metabolism, energy metabolism and metabolism of cofactors and vitamins. These metabolic adjustments could cause the cell to go into dormancy, thus promoting S. aureus to convert to persisters. In addition, RpvA could upregulate the expression of virulence genes including hla, hlgA, hlgB, hlgC, lukF, lukS, lukD, sea and coa, and carotenoid biosynthesis genes (crtI, crtM, crtN). Gel shift assay confirmed that RpvA could bind to the promoters of candidate target genes hla, hlgB and crtM, thus promoting S. aureus virulence. Because of the important functions of the RpvA, it may serve as an attractive target for developing new drugs and vaccines to more effectively control S. aureus infections.