In vitro Characterization of the LytSR two component system in Staphylococcus aureus

Abstract

S. aureus, is a major gram‐positive pathogen, because of its remarkable capacity to develop resistance against different antimicrobial. Autolysins are known to regulate cell growth, cell division and biofilm formation. It has been shown that in Staphylococcus aureus, autolysis (PG hydrolases) and biofilm formation is regulated by the LytSR two component systems. In this study we investigated the LytSR signal transduction mechanism by performing kinetic characterization of the autophosphorylation of the histidine kinase LytS, and a subsequent phosphoryl transfer to its cognate response regulator LytR using radiolabel Adenosine‐5′‐triphosphate (ATP). For the purpose of the above in vitro experiments, we have cloned and purified LytS lacking its transmembrane domains and the full length LytR. We found that LytS has the ability to catalyze an ATP‐dependent autophosphorylation. Preliminary results of the pseudo first order kinetic reaction suggest that LytS is an active kinase. In addition, we show that activity of LytS depends on the concentration of Ca2+ions but not K+ ions. This research is funded by Natural Sciences and Engineering Research Council of Canada (NSERC).