Member of the two-component regulatory system WalK/WalR that regulates genes involved in cell wall metabolism, virulence regulation, biofilm production, oxidative stress resistance and antibiotic resistance via direct or indirect regulation of autolysins (PubMed:17827301, PubMed:22825451). Functions as a transcription regulator by direct binding to promoter regions. Positively controls the cell wall-hydrolytic activity through regulation of atlA and lytM, as well as induces transcription of isaA, sceD, ssaA, and four ssaA-related genes. Binds directly to the lytM, ssaA and isaA promoter regions in vitro. Phosphorylated by WalK (PubMed:14762013). Phosphorylated by PknB on Thr-101 (By similarity).