The cvfC operon of Staphylococcus aureus contributes to virulence via expression of the thyA gene

The cvfC operon of Staphylococcus aureus comprises four genes, cvfC1, cvfC2, cvfC3, and cvfC4. The cvfC3-disrupted mutant, M1262, produces less hemolysin and has attenuated virulence in silkworms and mice. Although introduction of the cvfC3 gene restores the decreased hemolysin production of M1262, the cvfC operon is more effective for the complementation, suggesting that cvfC operon function is impaired in M1262. In this study, we performed a microarray analysis and identified 21 genes with altered expression in M1262. The expression of virulence genes and metabolic genes, including thyA, was changed in M1262. The decreased expression of thyA in M1262 was restored by introducing a plasmid containing the cvfC operon. Introduction of a thyA gene-containing plasmid in M1262 restored hemolysin production and virulence against silkworms. Both M1262 and a thyA-deletion mutant exhibited slow growth in the presence of the detergent Triton-X 100. The growth defect of M1262 in the presence of Triton-X 100 was restored by the introduction of thyA. These results suggest that the cvfC operon contributes to hemolysin production, detergent resistance, and virulence of S. aureus in host animals via thyA expression.