关键词: 烯醇化酶, 链球菌致热外毒素B, eno基因缺失突变株, 化脓性链球菌

Abstract:

Group A Streptococci(GAS) is an important Gram-positive human pathogen, which causes mild to severe diseases. The ability of GAS to cause infection is associated with the production of an array of secreted and cell-wall associated virulence factors. One key secreted virulence factor is a cysteine protease called streptococcal pyrogenic exotoxin B(SpeB). This protein is initially secreted as a 40000 precursor zymogen, and is subsequently cleaved to a 28000 mature form. The conversion of the zymogen form of SpeB is extremely complex and unclear. In this paper we reported a protein involved in the maturation of SpeB in the supernatant of Group A Streptococci. This protein was the streptococcus host plasminogen receptor, enolase(Eno) identified by MS/MS analysis. We constructed the eno in-deletion mutants by the method of gene knock out and investigated the correlation of enolase and maturation of SpeB in GAS. Western blot analysis and protease assays revealed a delay in the maturation of SpeB in supernatant of the eno in-deletion mutants comparing with the wild type strains. Far-Western blot analysis showed that SpeB can bind to Eno, which interact with each other. These data imply that the function of Eno, as like HtrA and RopA, is a chaperone, the regulation of protease activity and the mechanism of secretion in GAS.

Key words: Enolase, Streptococcal pyogenic exotoxin B, Eno in-deletion mutant, Streptococcus pyogenes