The srhSR gene pair from Staphylococcus aureus: Genomic and proteomic approaches to the identification and characterization of gene function

Systematic analysis of the entire two-component signal transduction system (TCSTS) gene complement of Staphylococcus aureus revealed the presence of a putative TCSTS (designated SrhSR) which shares considerable homology with the ResDE His-Asp phospho-relay pair of Bacillus subtilis. Disruption of th e srhSR gene pair resulted in a dramatic reduction in growth of the srhSR m utant, when cultured under anaerobic conditions, and a 3-log attenuation in growth when analyzed in the murine pyelonephritis model. To further unders tand the role of SrhSR, differential display two-dimensional gel electropho resis was used to analyze the cell-free extracts derived from the srhSR mut ant and the corresponding wild type. Proteins shown to be differentially re gulated were identified by mass spectrometry in combination with protein da tabase searching. An srhSR deletion led to changes in the expression of pro teins involved in energy metabolism and other metabolic processes including arginine catabolism, xanthine catabolism, and cell morphology. The impaire d growth of the mutant under anaerobic conditions and the dramatic changes in proteins involved in energy metabolism shed light on the mechanisms used by S. aureus to grow anaerobically and indicate that the staphylococcal Sr hSR system plays an important role in the regulation of energy transduction in response to changes in oxygen availability. The combination of proteomi cs, bio-informatics, and microbial genetics employed here represents a powe rful set of techniques which can be applied to the study of bacterial gene function.