TY - JOUR
T1 - The M protein is dispensable for maturation of streptococcal cysteine protease SpeB
AU - Zimmerlein, Björn
AU - Park, Hae Sun
AU - Li, Shaoying
AU - Podbielski, Andreas
AU - Cleary, P. Patrick
PY - 2005/2
Y1 - 2005/2
N2 - The streptococcal pyrogenic exotoxin B (SpeB) is an important virulence factor of group A streptococci (GAS) with cysteine protease activity. Maturation of SpeB to a proteolytically active form was suggested to be dependent on cell-wall-anchored M1 protein, the major surface protein of GAS (M. Collin and A. Olsén, Mol. Microbiol. 36:1306-1318, 2000). Collin and Olsén showed that mutant GAS strains expressing truncated M protein secrete a conformationally different form of unprocessed SpeB with no proteolytic activity. Alternatively, we hypothesized that a truncated M protein may interfere with processing of this secreted protease, and therefore we tested cysteine protease activity in genetically defined mutant strains that express either no M protein or membrane-anchored M protein with an in-frame deletion of the AB repeat region. Measurements of SpeB activity by cleavage of a substrate n-benzoyl-Pro-Phe-Arg-p-nitroanilide hydrochloride showed that the proteolytic activities in culture supernatants of both mutants were similar to those from the wild-type strain. In addition, Western blot analysis of culture supernatants showed that SpeB expression and processing to a mature form was unaffected by either deletion mutation. Therefore, we conclude that M protein is not required for maturation of the streptococcal cysteine protease SpeB.
AB - The streptococcal pyrogenic exotoxin B (SpeB) is an important virulence factor of group A streptococci (GAS) with cysteine protease activity. Maturation of SpeB to a proteolytically active form was suggested to be dependent on cell-wall-anchored M1 protein, the major surface protein of GAS (M. Collin and A. Olsén, Mol. Microbiol. 36:1306-1318, 2000). Collin and Olsén showed that mutant GAS strains expressing truncated M protein secrete a conformationally different form of unprocessed SpeB with no proteolytic activity. Alternatively, we hypothesized that a truncated M protein may interfere with processing of this secreted protease, and therefore we tested cysteine protease activity in genetically defined mutant strains that express either no M protein or membrane-anchored M protein with an in-frame deletion of the AB repeat region. Measurements of SpeB activity by cleavage of a substrate n-benzoyl-Pro-Phe-Arg-p-nitroanilide hydrochloride showed that the proteolytic activities in culture supernatants of both mutants were similar to those from the wild-type strain. In addition, Western blot analysis of culture supernatants showed that SpeB expression and processing to a mature form was unaffected by either deletion mutation. Therefore, we conclude that M protein is not required for maturation of the streptococcal cysteine protease SpeB.
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U2 - 10.1128/IAI.73.2.859-864.2005
DO - 10.1128/IAI.73.2.859-864.2005
M3 - Article
C2 - 15664926
AN - SCOPUS:12844282320
VL - 73
SP - 859
EP - 864
JO - Infection and Immunity
JF - Infection and Immunity
SN - 0019-9567
IS - 2
ER -