Musser J M, Stockbauer K, Kapur V, Rudgers G W
Department of Pathology, Baylor College of Medicine, Houston, Texas 77030, USA.
Infect Immun. 1996 Jun;64(6):1913-7. doi: 10.1128/iai.64.6.1913-1917.1996.
Virtually all strains of the human pathogenic bacterium Streptococcus pyogenes express a highly conserved extracellular cysteine protease. The protein is made as an inactive zymogen of 40,000 Da and undergoes autocatalytic truncation to result in a 28,000-Da active protease. Numerous independent lines of investigation suggest that this enzyme participates in one or more phases of host-parasite interaction, such as inflammation and soft tissue invasion. Replacement of the single cysteine residue (C-192) with serine (C192S mutation) resulted in loss of detectable proteolytic activity against bovine casein, human fibronectin, and the low-molecular-weight synthetic substrate 7-amino-4-trifluoromethyl coumarin. The C192S mutant molecule does not undergo autocatalytic processing of zymogen to mature form. Taken together, these data support the hypothesis that C-192 participates in active-site formation and enzyme catalysis.
几乎所有人类致病细菌酿脓链球菌的菌株都表达一种高度保守的细胞外半胱氨酸蛋白酶。该蛋白最初是以40000道尔顿的无活性酶原形式产生的，经过自催化截短后形成28000道尔顿的活性蛋白酶。众多独立的研究线索表明，这种酶参与宿主与寄生虫相互作用的一个或多个阶段，如炎症和软组织侵袭。将单个半胱氨酸残基（C-192）替换为丝氨酸（C192S突变）导致对牛酪蛋白、人纤连蛋白和低分子量合成底物7-氨基-4-三氟甲基香豆素的可检测蛋白水解活性丧失。C192S突变体分子不会将酶原自催化加工成成熟形式。综上所述，这些数据支持C-192参与活性位点形成和酶催化的假说。
