Inactivation of the cysteine protease SpeB affects hyaluronic acid capsuleexpression in group A streptococci

The human pathogen Streptococcus pyogenes expresses several virulence facto rs that are required for the pathogens survival within the host and the con comitant development of disease. To examine the influence of one virulence factor, the extracellular cysteine protease SpeB, on the expression of othe r virulence factors, the speB structural gene of a serotype M3 and M49 stra in was inactivated. Morphologic examination, quantification of extracellula r hyaluronic acid capsule, and Northern blot analysis of the isogenic speB- mutants revealed a strain-dependent decrease of hyaluronic acid capsule pro duction and an increase in superoxide dismutase transcription. The transcri ption of streptolysin O (slo), di- and oligo-peptide permease (dpp, opp), h yaluronidase (hyl), streptokinase (ska) and streptococcal pyrogenic exotoxi n A (speA) was unaffected. (C) 2000 Academic Press.