Functional analysis of the YvrGHb two-component system of Bacillus subtilis: identification of the regulated genes by DNA microarray and northern blot analyses.

YvrGHb is a novel two-component system in Bacillus subtilis. The yvrG and yvrHb genes are considered to encode sensor kinase and response regulator respectively. We found that the YvrGHb system positively regulates the 7 transcriptional units (wprA, wapA-yxxG, dltABCDE, sunA, sunT-bdbA-yolJ-bdbB, yvrI-yvrHa, and sigX-rsiX), and negatively regulates the lytABC operon. wprA, wapA, lytB, and lytC encode the main cell surface proteins of B. subtilis. Furthermore, SigX [extracytoplasmic function sigma factor (ECF sigma factor)] relating to the cell surface homeostatic functions, was regulated by this system. The yvrGHb null mutant showed the unusual autolysis and higher susceptibility to the four kinds of antibiotics (aztreonam, cefepime, bacitracin, and fosfomycin). These results indicate that the YvrGHb system is important to maintain the overall state of the cell surface through transcriptional regulation.