M6型A群链球菌表面烯醇化酶和3-磷酸甘油醛脱氢酶特性的研究

表面烯醇化酶(surface enolase,SEN)和3-磷酸甘油醛脱氢酶(surface glyceraldehydes -3 - phosphate dehydro - genase,sGAPDH)都是A群链球菌(group A Streptococcus,GAS)没有踌膜结构的膜表面蛋白,它们可能在GAS感染中起到重要的作用.在本研究中,对SEN和sGAPDH在M6型GAS不同生长阶段(即在对数期和稳定期)的表达情况进行检测分析.取对数期(OD600 =0.5 -0.6)和稳定期(OD600 =1.5- 1.6)的GAS,分别测定SEN和sGAPDH活性.同时用变溶菌素(mutanolysin)提取这2个生长阶段细胞壁结合蛋白,用Western blot检测该提取物中的SEN和sGAPDH.结果表明在相同菌细胞浊度的条件下,SEN在M6型GAS对数期时的表达量及活性比其稳定期时的高45％左右.虽然sGAPDH的表达量较高但活性很低(＜0.07mM NADH/min),并且在这2个生长阶段没有明显的差异.

CHARACTERISTICS OF ENOLASE AND GLYCERALDEHYDE-3- PHOSPHATE DEHYDROGENASE ON THE SURFACE OF M6 -TYPE GROUP A Streptococcus

Streptococcal surface enolase(SEN) and surface glyceraldehyde-3-phosphate dehydrogenase(sGAPDH) are anchorless surface proteins on the surface of group A Streptococcus(GAS) with the possible roles in the infection of GAS.In this study,the expression of SEN and sGAPDH of M6-type GAS at the log phase and stationary phase were examined.The SEN and GAPDH activities on the surface of M6-type GAS were detected at logarithmic phase(OD600=0.5-0.6) and stationary phase(OD600=1.5-1.6).The cell wall-associated SEN and sGAPDH of M6-type GAS were extracted with mutanolysin and were analyzed by Western blot at the two growing phase.The results indicated that the expressing level and the activity of SEN at M6-type GAS logarithmic phase was significantly higher than(~45%) those at stationary phase using the same cell density.Although the expressing level of sGAPDH of M6-type GAS was high its activity was low(<0.07mM NADH/ml).In addition,the expressing levels of sGAPDH did not have significant differences between two phases.