Jobin Marie-Claude, Grenier Daniel
Groupe de Recherche en Ecologie Buccale, Faculté de Médecine Dentaire, Université Laval, Quebec, QC, Canada G1K 7P4.
FEMS Microbiol Lett. 2003 Mar 14;220(1):113-9. doi: 10.1016/S0378-1097(03)00088-0.
Streptococcus suis is an important worldwide swine pathogen. In this study, we investigated the production of proteases by S. suis serotype 2. Proteases were identified and characterized using chromogenic and fluorogenic assays and zymography. An Arg-aminopeptidase with a molecular mass of 55 kDa was found to be both cell-associated and extracellular. Cell-associated chymotrypsin-like and caseinase activities, belonging to the serine- and metalloprotease classes respectively, were also detected. Lastly, a dipeptidyl peptidase IV (DPP IV) with a molecular mass of 70 kDa was detected in both whole cells and culture supernatants of S. suis serotype 2. Arg-aminopeptidase, caseinase and DPP IV activities were detected in all strains of S. suis serotype 2 tested whereas the chymotrypsin-like activity was only detected in European virulent strains of serotype 2. The optimum pH for all four proteases was between 6 and 8, and the optimum temperature ranged from 25 to 42 degrees C. This is the first report on the production of proteases by S. suis. Further investigations will determine the possible contribution of these proteases in the pathogenicity of S. suis serotype 2.
猪链球菌是一种在全球范围内重要的猪病原体。在本研究中，我们调查了2型猪链球菌蛋白酶的产生情况。使用显色法、荧光法和酶谱法对蛋白酶进行了鉴定和表征。发现一种分子量为55 kDa的精氨酸氨肽酶既与细胞相关又存在于细胞外。还检测到了与细胞相关的类胰凝乳蛋白酶活性和酪蛋白酶活性，它们分别属于丝氨酸蛋白酶和金属蛋白酶类别。最后，在2型猪链球菌的全细胞和培养上清液中均检测到一种分子量为70 kDa的二肽基肽酶IV（DPP IV）。在所测试的所有2型猪链球菌菌株中均检测到了精氨酸氨肽酶、酪蛋白酶和DPP IV活性，而类胰凝乳蛋白酶活性仅在欧洲2型强毒株中检测到。所有这四种蛋白酶的最适pH在6至8之间，最适温度范围为25至42摄氏度。这是关于2型猪链球菌产生蛋白酶的首次报道。进一步的研究将确定这些蛋白酶在2型猪链球菌致病性中可能发挥的作用。
