biostudies-literatureGajdiss MDeutsche ForschungsgemeinschaftE870https://www.ebi.ac.uk/biostudies/studies/S-EPMC7355866biostudies-literatureUnknown8(6)Staphylococcus aureus is a facultative pathogen that can encode numerous antibiotic resistance and immune evasion genes and can cause severe infections. Reduced susceptibility to last resort antibiotics such as vancomycin and daptomycin is often associated with mutations in walRK, an essential two-component regulatory system (TCS). This study focuses on the WalK accessory membrane proteins YycH and YycI and their influence on WalRK phosphorylation. Depletion of YycH and YycI by antisense RNA caused an impaired autolysis, indicating a positive regulatory function on WalK as has been previously described. Phosphorylation assays with full-length recombinant proteins in phospholipid liposomes showed that YycH and YycI stimulate WalK activity and that both regulatory proteins are needed for fulMicroorganismsYycH and YycI Regulate Expression of Staphylococcus aureus Autolysins by Activation of WalRK Phosphorylation.PMC7355866Bi504-8/1-8/3Bi504-12/1Gajdiss MMonk IRSib EStinear TPBierbaum GFunk THort MDietrich AKienemund JBertsche UfalseYycH and YycI Regulate Expression of Staphylococcus aureus Autolysins by Activation of WalRK Phosphorylation.Staphylococcus aureus is a facultative pathogen that can encode numerous antibiotic resistance and immune evasion genes and can cause severe infections. Reduced susceptibility to last resort antibiotics such as vancomycin and daptomycin is often associated with mutations in walRK, an essential two-component regulatory system (TCS). This study focuses on the WalK accessory membrane proteins YycH and YycI and their influence on WalRK phosphorylation. Depletion of YycH and YycI by antisense RNA caused an impaired autolysis, indicating a positive regulatory function on WalK as has been previously described. Phosphorylation assays with full-length recombinant proteins in phospholipid liposomes showed that YycH and YycI stimulate WalK activity and that both regulatory proteins are needed for ful2020-01-01T00:00:00Z2020 Jun2025-04-19T18:02:50.141Z2025-04-19T18:02:50.141ZS-EPMC73558663252691510.3390/microorganisms8060870