The essential YycFG two-component system of Bacillus subtilis.

The YycFG two-component system, highly conserved in the low G+C gram positives, is essential for cell viability in most organisms in which it has been studied. The system is organized within an operon that includes at least one but often three to four other genes. Products of two of these genes, yycH and yycI, have been shown to have a regulatory role on this two-component system. Immunofluorescent studies identified YycG kinase localization at the cell division sites consistent with its role in regulating cell divisional processes. The essential nature and operon organization of this system commanded special requirements in studying this system genetically. This chapter presents methods utilized in identifying the regulatory circuit that controls the activity of the YycG kinase in Bacillus subtilis. Most aspects of our approaches are applicable to other two-component systems in B. subtilis and the gram positives. Some are limited to essential systems, such as the YycFG system.