Caticha O, Li Y, Griffin J, Winge D, Odell W D
Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City 84132.
Endocrinology. 1993 Feb;132(2):667-73. doi: 10.1210/endo.132.2.8425486.
Studies from our laboratory have demonstrated that human CG (hCG), human LH, (hLH), and an hCG-like protein extracted from Xanthomonas maltophilia were able to induce Candida albicans transition from the blastospore to the germ tube stage. In the present study, we describe the characterization of an hCG-like material extracted from Candida albicans blastospores (CaCGLP), which is potent in inducing transition and presumably represents the endogenous transition-inducing substance. This material was extracted from Candida albicans blastospores with glacial acetic acid and purified by affinity chromatography using a polyclonal rabbit anti-hCG antibody. The product obtained is a 68-kilodalton single band protein, as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis. Under reduced conditions a protein smear is seen. Amino acid analysis showed a predominance of glycine (22%), followed by serine (12%), and glutamate (12%). This protein reacted in the following hCG immunoassays: 1) a polyclonal rabbit anti-hCG equilibrium assay, 2) a carboxyl-tail hCG equilibrium assay, 3) two hCG equilibrium assays using monoclonal antibodies (CG no. 4 and CG no. 9), 4) a free alpha-subunit equilibrium assay using a monoclonal antibody, and 5) an ultrasensitive immunoradiometric assay for hCG which does not cross-react with hLH, nor the free beta-subunit of hCG. The CaCGLP showed no reaction in a specific hLH immunoradiometric assay. When CaCGLP was tested in the transition assay, in the presence of 4% rat serum, it was found that this protein was 100 times more potent than hCG in producing Candida albicans transition. We conclude that Candida albicans produces a protein that has certain tertiary structure similarities to hCG and that this material is able to induce germ tube formation. We postulate that CaCGLP has an autocrine/paracrine effect in Candida albicans as a transition factor to control its own pathogenicity.
我们实验室的研究表明，人绒毛膜促性腺激素（hCG）、人促黄体生成素（hLH）以及从嗜麦芽窄食单胞菌中提取的一种hCG样蛋白，能够诱导白色念珠菌从芽生孢子转变为芽管阶段。在本研究中，我们描述了从白色念珠菌芽生孢子中提取的一种hCG样物质（CaCGLP）的特性，该物质在诱导转变方面具有强大作用，可能代表内源性转变诱导物质。这种物质用冰醋酸从白色念珠菌芽生孢子中提取，并使用兔抗hCG多克隆抗体通过亲和色谱法进行纯化。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和蛋白质免疫印迹分析，得到的产物是一条68千道尔顿的单条带蛋白。在还原条件下可见蛋白质条带拖尾现象。氨基酸分析显示甘氨酸占主导（22%），其次是丝氨酸（12%）和谷氨酸（12%）。该蛋白在以下hCG免疫测定中呈阳性反应：1）兔抗hCG多克隆抗体平衡测定；2）羧基末端hCG平衡测定；3）使用单克隆抗体（CG 4号和CG 9号）的两种hCG平衡测定；4）使用单克隆抗体的游离α亚基平衡测定；5）一种超灵敏的hCG免疫放射测定法，该方法与hLH以及hCG的游离β亚基均无交叉反应。CaCGLP在特定的hLH免疫放射测定中无反应。当在转变测定中对CaCGLP进行测试时，发现在存在4%大鼠血清的情况下，这种蛋白在促使白色念珠菌转变方面的效力比hCG强100倍。我们得出结论，白色念珠菌产生一种与hCG具有某些三级结构相似性的蛋白，并且这种物质能够诱导芽管形成。我们推测CaCGLP在白色念珠菌中作为一种转变因子具有自分泌/旁分泌作用，以控制其自身的致病性。
