Stimuli that induce production of Candida albicans extracellular aspartyl proteinase.
Stimuli that induce production of Candida albicans extracellular aspartyl proteinase.
复制标题
DOI：
10.1099/00221287-139-7-1643
复制
发表时间：
1993-07
期刊：
影响因子：
--
通讯作者：
Claude G. Lerner;Robert C. Goldman
中科院分区：
文献类型：
--
作者：
Claude G. Lerner;Robert C. Goldman
几种机会性真菌病原体假丝酵母产生细胞外N-乙酰基蛋白酶，其可以帮助生物体侵入和定殖宿主组织，逃避宿主免疫应答并从蛋白质来源同化氮。虽然在培养的C.已知白念珠菌引起蛋白酶产生，但控制蛋白酶诱导调节的精确分子机制尚不清楚。我们已经研究了各种大分子诱导蛋白酶生产的能力，使用化学定义的氮限制生长培养基和快速，灵敏的微量荧光测定培养上清液中的蛋白酶活性。BSA和细胞外基质蛋白胶原诱导蛋白酶的产生。聚-L-和聚-D-谷氨酸的均聚物也诱导蛋白酶活性，而聚甘氨酸，硫酸肝素和硫酸葡聚糖没有。因此，蛋白酶诱导刺激的分子识别不是高度立体特异性的，但显然需要主链和侧链的相互作用。长度为8个或更多残基的肽通常诱导蛋白酶产生，而大多数较短的肽则不诱导蛋白酶产生。这些数据表明，小于7个残基的小肽通过肽转运的内化不是蛋白酶产生的诱导信号，因为假丝酵母二肽和寡肽渗透酶不能有效地转运大于6-7个残基的肽。此外，一种紧密结合的念珠菌蛋白酶合成抑制剂（Ki = 0.17 nM）阻止了C.白念珠菌对BSA作为唯一的氮源通过阻断蛋白质降解。这些培养上清液中蛋白酶的免疫检测表明，除了足够大小的肽片段外，完全完整的蛋白质能够诱导蛋白酶产生。（250字处删节）
Several species of the opportunistic fungal pathogen Candida produce an extracellular aspartyl proteinase that may assist the organism to invade and colonize host tissues, evade the host immune response and assimilate nitrogen from proteinaceous sources. Although addition of exogenous proteins, such as bovine serum albumin (BSA), to cultures of C. albicans is known to elicit proteinase production, the precise molecular mechanisms controlling regulation of proteinase induction are unknown. We have examined the ability of a variety of macromolecules to induce proteinase production using a chemically-defined nitrogen-limited growth medium and a rapid, sensitive microtitre fluorescent assay for proteinase activity in culture supernatants. BSA and the extracellular matrix protein collagen induced proteinase production. Homopolymers of both poly-L- and poly-D-glutamate also induced proteinase activity, whereas polyglycine, heparin sulphate and dextran sulphate did not. Thus, molecular recognition of proteinase-inducing stimuli is not highly stereospecific, but apparently requires both main- and side-chain interactions. Peptides 8 or more residues in length generally induced proteinase production while most shorter peptides did not. These data reveal that internalization of small peptides with less than 7 residues by peptide transport was not the inducing signal for proteinase production, since Candida dipeptide and oligopeptide permeases do not efficiently transport peptides of more than 6-7 residues. In addition a tight-binding synthetic inhibitor of Candida proteinase (Ki = 0.17 nM) prevented growth of C. albicans on BSA as a sole nitrogen source by blocking protein degradation. Immunodetection of proteinase in these culture supernatants suggests that fully intact proteins, in addition to peptide fragments of sufficient size, are capable of inducing proteinase production.(ABSTRACT TRUNCATED AT 250 WORDS)