Banerjee A, Ganesan K, Datta A
Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
J Gen Microbiol. 1991 Oct;137(10):2455-61. doi: 10.1099/00221287-137-10-2455.
Candida albicans and some other pathogenic Candida species, when grown in a medium containing a protein as a sole source of nitrogen, secrete an acid proteinase. Culture supernatants were assayed for proteinase activity, and were also analysed by Western blotting with antibodies raised and affinity-purified against proteinase of C. albicans. Proteinases secreted by C. tropicalis and C. parapsilosis were antigenically related to that of C. albicans, but had different molecular masses. The proteinases secreted by C. lipolytica, C. rugosa and C. lusitaniae were not antigenically related. The kinetics of proteinase secretion by C. albicans were monitored by activity and by Western blotting. With BSA as the nitrogen source, proteinase secretion increased exponentially until about 16 h. Culture supernatants of BSA-grown cultures accumulated proteinase to about a 1000-fold higher level than those of ammonium-sulphate-grown cultures. In vivo labelling experiments showed that proteinase was not detectably accumulated in the cells, but was secreted immediately after synthesis. Immunoprecipitation of in vitro translated poly(A)-containing RNA identified a putative pre-protein of about 54 kDa. As well as BSA, other proteins (haemoglobin, ovalbumin, histone), peptone and tryptone, when used as nitrogen sources, could induce proteinase, but to different levels. When Casamino acids or an amino acid mixture (equivalent to the composition of BSA) was used as nitrogen source, no induction was observed. Ammonium sulphate, or any other ammonium salt, repressed secretion of proteinase.
白色念珠菌及其他一些致病性念珠菌在以蛋白质作为唯一氮源的培养基中生长时，会分泌一种酸性蛋白酶。对培养上清液进行蛋白酶活性测定，并使用针对白色念珠菌蛋白酶制备并亲和纯化的抗体进行蛋白质印迹分析。热带念珠菌和近平滑念珠菌分泌的蛋白酶与白色念珠菌的蛋白酶存在抗原相关性，但分子量不同。解脂念珠菌、皱落念珠菌和葡萄牙念珠菌分泌的蛋白酶与白色念珠菌的蛋白酶不存在抗原相关性。通过活性和蛋白质印迹法监测白色念珠菌蛋白酶分泌的动力学。以牛血清白蛋白（BSA）作为氮源时，蛋白酶分泌呈指数增长，直至约16小时。以BSA为氮源培养的上清液中积累的蛋白酶水平比以硫酸铵为氮源培养的上清液高约1000倍。体内标记实验表明，蛋白酶在细胞中未检测到积累，而是在合成后立即分泌。对体外翻译的含聚腺苷酸（poly(A)）RNA进行免疫沉淀，鉴定出一种约54 kDa的假定前体蛋白。除了BSA外，其他蛋白质（血红蛋白、卵清蛋白、组蛋白）、蛋白胨和胰蛋白胨用作氮源时，也能诱导蛋白酶产生，但诱导水平不同。当使用酪蛋白氨基酸或氨基酸混合物（等同于BSA的组成）作为氮源时，未观察到诱导作用。硫酸铵或任何其他铵盐会抑制蛋白酶的分泌。
