A 2-COMPONENT SIGNAL-TRANSDUCTION SYSTEM ESSENTIAL FOR GROWTH OF BACILLUS-SUBTILIS - IMPLICATIONS FOR ANTIINFECTIVE THERAPY

A two-component signal transduction system encoded by the yycF and yyc G genes is part of an operon containing three genes, yycH, yycI, and y ycJ, with no known function and a gene, yycK, coding for an HtrA-like protease, This operon was transcribed during growth,and its transcript ion shut down as the cells approached stationary phase. This decreased transcription was not Spo0A dependent. The HtrA protease gene was sep arately controlled during sporulation from a sigma(G) promoter. Studie s using insertional inactivation plasmids revealed that neither yycF n or yycG could be inactivated, whereas the other genes were inactivated without loss of viability. A temperature-sensitive YycF response regu lator mutant was isolated and shown to have an H215P mutation in a put ative DNA-binding domain which is closely related to the OmpR family o f response regulators. At the nonpermissive temperature, cultures of t he mutant strain stopped growth within 30 min, and this was followed b y a decrease in optical density. Microscopically, many of the cells ap peared to retain their structure while being empty of their contents, The essential processes regulated by this two-component system remain unknown. A search of the genome databases revealed YycP, YycG, and Yyc J homologues encoded by three linked genes in Streptococcus pyogenes, The high level of identity of these proteins (71% for YycF) suggests t hat this system may play a similar role in gram-positive pathogens.