KEX2 influences Candida albicans proteinase secretion and hyphal formation
KEX2 influences Candida albicans proteinase secretion and hyphal formation
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DOI：
10.1074/jbc.272.46.28954
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发表时间：
1997-11-14
影响因子：
4.8
通讯作者：
Agabian, N
中科院分区：
文献类型：
--
作者：
Newport, G;Agabian, N
白色念珠菌具有至少7个差异表达基因，编码毒力相关的分泌型乙酰基蛋白酶（Sap），Sap DNA序列预测前蛋白中赖氨酸精氨酸残基的翻译后加工，使人联想到酿酒酵母α因子的成熟，其中前多肽原通过枯草杆菌蛋白酶样前蛋白转化酶Kex 2转化为生物活性信息素。为了调查一个C.白念珠菌KEX 2同源物在Sap激活中的作用，基于KEX 2功能进行遗传选择，获得了一株Sap激活的KEX 2菌株。酿酒酵母用C.白色念珠菌基因组DNA文库中，并筛选活性α-因子的产生。测定阳性克隆的杀伤毒素活性，另一种Kex 2依赖性表型。挽救这两个缺陷的质粒含有编码与S同源的蛋白质的序列。酿酒酵母Kex 2. C.白念珠菌REX 2通过连续突变失活，突变体继续分泌活性Sap 2;然而，酶被异常加工并以降低的水平分泌。出乎意料的是，无效突变体不能形成菌丝，而是分化成异常形状的细胞。用含KEX 2的质粒转化无效突变体后，恢复了正常处理Sap 2和形成菌丝的能力。
Candida albicans possesses at least seven differentially expressed genes that encode virulence-related secretory aspartyl proteinases (Saps), Sap DNA sequences predict post-translational processing at lysine arginine residues in the preproteins, reminiscent of the maturation of Saccharomyces cerevisiae alpha-factor, where a prepropolypeptide is converted into a biologically active pheromone by Kex2, a subtilisin-like proprotein convertase. To investigate involvement of a C. albicans KEX2 homologue in Sap activation, a genetic selection was performed based on KEX2 function, A kex2 strain of S. cerevisiae was transformed with a C. albicans genomic DNA library and screened for the production of active alpha-factor. Positive clones were assayed for killer toxin activity, another Kex2-dependent phenotype. Plasmids that rescued both defects contained a sequence encoding a protein homologous to S. cerevisiae Kex2. Both alleles of the C. albicans REX2 were inactivated by successive mutations, Null mutants continued to secrete active Sap2; however, the enzyme was abnormally processed and secreted at reduced levels, Unexpectedly, null mutants were incapable of forming hyphae, instead differentiating into aberrantly shaped cells. The ability to normally process Sap2 and form hyphae was restored upon transformation of null mutants with a KEX2-containing plasmid.