Togni Giuseppe, Sanglard Dominique, Quadroni Manfredo, Foundling Stephen I, Monod Michel
Institut de Microbiologie, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
Laboratoire de Mycologie, Service de Dermatologie, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
Microbiology (Reading). 1996 Mar;142 ( Pt 3):493-503. doi: 10.1099/13500872-142-3-493.
The 40 kDa secreted aspartyl proteinase (Sapt1) of Candida tropicalis is a pepsin-like enzyme encoded by the SAPT1 gene. According to the deduced amino acid sequence. Sapt1 has a putative preproregion of 60 amino acids preceding the mature enzyme. Maturation and processing of Sapt1 was analysed in C. tropicalis and Saccharomyces cerevisiae strains expressing wild-type or mutated forms of SAPT1. In S. cerevisiae, the glycosylated 46 kDa proenzyme was converted to the mature 40 kDa form of Sapt1 by KEX2-dependent proteolytic cleavage following the Lys59-Arg60 sequence. The replacement of Lys59-Arg60 by Lys59-Gly60 revealed that the precursor can be processed by an autocatalytic cleavage. This alternative processing pathway to produce mature Sapt1 is less efficient than the Kex2-mediated pathway. Finally, it was shown that in C. tropicalis and S. cerevisiae the removal of the proregion was a prerequisite for the secretion of Sapt1.
热带假丝酵母的40 kDa分泌天冬氨酸蛋白酶（Sapt1）是一种由SAPT1基因编码的类胃蛋白酶酶。根据推导的氨基酸序列，Sapt1在成熟酶之前有一个60个氨基酸的假定前原区。在表达野生型或突变形式SAPT1的热带假丝酵母和酿酒酵母菌株中分析了Sapt1的成熟和加工过程。在酿酒酵母中，糖基化的46 kDa酶原通过依赖KEX2的蛋白水解切割，按照Lys59-Arg60序列转化为成熟的40 kDa Sapt1形式。将Lys59-Arg60替换为Lys59-Gly60表明前体可以通过自催化切割进行加工。这种产生成熟Sapt1的替代加工途径比Kex2介导的途径效率低。最后，结果表明在热带假丝酵母和酿酒酵母中，前区的去除是Sapt1分泌的先决条件。
