Deciphering the function of Com_YlbF domain-containing proteins in Staphylococcus aureus

The Com_YlbF domain-containing proteins inhibit sporulation, competition, and biofilm formation by affecting the activity of ribonuclease RNase-Y in Bacillus subtilis. Similar Com_YlbF proteins are found in Staphylococcus aureus, but their function is yet to be determined. This study investigates the role of Com_YlbF domain-containing proteins (Qrp/YheA, YmcA, and YlbF) in S. aureus by evaluating the impact of qrp/yheA, ymcA, and ylbF gene deletion on biofilm formation, PIA/PNAG production, and hemolytic capacity. It was found that deletion of the three qrp/yheA, ymcA, and ylbF genes in S. aureus produced a decrease in biofilm formation, a slight decrease in PIA/PNAG production, and a decrease in its hemolytic capacity. Global transcriptional analysis in the mutant strain showed dysregulation of several genes associated with pathogenesis, most notably a decreased expression of the agrA gene (quorum sensing system), the delta, alpha, and gamma hemolysins, as well as the sdrC genes and eap/map (adhesion proteins) genes. It also showed an attenuation of virulence, manifesting as enhanced survival among Galleria mellonella larvae and BALB/c mice, possibly associated due to disrupted RNase-Y activity when the qrp/yheA, ymcA, and ylbF are deleted. In conclusion, this work supports the hypothesis that this new family of proteins containing a Com_YlbF domain is involved in the regulation of genes related to biofilm formation, hemolysis, and virulence in S. aureus through a change in RNase-Y activity.