Identification of rgg-regulated exoproteins of Streptococcus pyogenes

Streptococcus pyogenes secretes many proteins that influence host-pathogen interactions. Despite their importance, relatively little is known about th e regulation of these proteins. The rgg gene (also known as ropB) is requir ed for the expression of streptococcal erythrogenic toxin B (SPE B), an ext racellular cysteine protease that contributes to virulence. Proteomics was used to determine if rgg regulates the expression of additional exoproteins . Exponential- and stationary-phase culture supernatant proteins made by S, pyogenes NZ131 rgg and NZ131 speB were separated by two-dimensional electr ophoresis, Differences were identified in supernatant proteins from both ex ponential- and stationary-phase cultures, although considerably more differ ences cr ere detected among stationary-phase supernatant proteins, Forty-tw o proteins were identified by peptide fingerprinting with matrix-assisted l aser desorption mass spectrometry. Mitogenic factor, DNA entry nuclease (op en reading frame [ORF 226]), and ORF 953, which has no known function, were more abundant in the culture supernatants of the rgg mutant compared to th e speB mutant. ClpB, lysozyme, and autolysin were detected in the culture s upernatant of the speB mutant but not the rgg mutant. To determine if Rgg a ffected protein expression at the transcriptional level, real-time (TaqMan) reverse transcription (RT)-PCR was used to quantitate Rgg-regulated transc ripts from NZ131 wild-type and speB and rgg mutant strains. The results obt ained with RT-PCR correlated with the proteomic data. We conclude that Rgg regulates the transcription of several genes expressed primarily during the stationary phase of growth.