This entry represents signal transduction histidine kinases such as LiaS from Bacillus subtilis and VraS from Staphylococcus aureus. LiaS is a member of the two-component regulatory system LiaS (HK)/LiaR(RR), which is probably involved in response to a subset of cell wall-active antibiotics that interfere with the lipid II cycle in the cytoplasmic membrane (bacitracin, nisin, ramoplanin and vancomycin) []. LiaS may also be involved in response to cationic antimicrobial peptides and secretion stress. VraS is a member of the two-component regulatory system VraS/VraR involved in the control of the cell wall peptidoglycan biosynthesis. It probably activates VraR by phosphorylation [].