title: The Essential WalK Histidine Kinase and WalR Regulator Differentially Mediate Autolysis ofStaphylococcus aureusRN4220.
abstract: The two-component regulatory system, WalR/WalK is necessary for growth of different gram-positive bacteria, includingStaphylococcus aureus. In present study, we confirmed the essentiality of both the histidine kinase protein WalK and the response regulator WalR for growth usingS. aureusRN4220 strain and demonstrated that the histidine kinase protein WalK and the response regulator WalR function differently in regulation of staphylococcal autolysis. The down-regulation ofwalRexpression effectively inhibited Triton X-100-induced lysis and had a weak impact on bacterial tolerance to penicillin induced cell lysis. In contrast, the down-regulation ofwalKexpression had no influence on either Triton X-100- or penicillin-caused autolysis. Moreover, we determined the effect of WalR and WalK on bacterial hydrolase activity using a zymogram analysis. The results showed that the cell lysate of down-regulatedwalRexpression mutant displayed several bands of decreased cell wall hydrolytic activities; however, the down-regulation of WalK had no dramatic impact on the hydrolytic activities. Furthermore, we examined the impact of WalR on the transcription ofcidAassociated with staphylococcal autolysis, and the results showed that the down-regulation of WalR led to decreased transcription ofcidAin the log phase of growth. Taken together, the above results suggest that the essential WalR response regulator and the essential WalK histidine kinase might differently control bacterial lysis in RN4220 strain.
authors.affiliation: Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota. 1971 Commonwealth Ave. St. Paul. MN 55108, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Zheng
authors.affiliation: Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota. 1971 Commonwealth Ave. St. Paul. MN 55108, USA.
authors.forename: Meiying
authors.initials: M
authors.lastname: Yan
authors.affiliation: Promega Corporation, Madison, WI 53711, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: Fan
authors.affiliation: Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota. 1971 Commonwealth Ave. St. Paul. MN 55108, USA.
authors.forename: Yinduo
authors.initials: Y
authors.lastname: Ji
keywords: S. aureus; autolysis; essential WalRK; tolerance of penicillin