Klotz S A, Rutten M J, Smith R L, Babcock S R, Cunningham M D
Department of Medicine, Veterans Affairs Medical Center, Kansas City, MO.
Microb Pathog. 1993 Feb;14(2):133-47. doi: 10.1006/mpat.1993.1014.
The adherence of Candida albicans to the extracellular matrix proteins type I collagen and fibronectin (Fn) is dependent upon the presence of extracellular calcium. In the absence of calcium, 14 +/- 3% of yeast cells added to type I collagen adhered, whereas 62 +/- 3% of yeast cells adhered in the presence of 2 mM calcium. EDTA and EGTA reduced C. albicans adherence in a dose-dependent manner. Calcium, and to a lesser extent, cesium and magnesium, enhanced yeast cell adherence. The fluorescent probe, terbium (Tb+3), bound to the surface of yeast cells in a dose-dependent manner demonstrating the presence of cationic metal-binding sites on the yeast cell surface. When extracts of C. albicans yeast cells were applied to columns of Fn or gelatin coupled to agarose, two surface proteins of C. albicans were specifically eluted with 10 mM EDTA, 2% alpha-methylmannopyranoside or an Arg-Gly-Asp-containing peptide. The fungal proteins had relative molecular masses of 60,000 and 105,000 in the unreduced state. The proteins were present in the cell membrane as well as the cell wall and were demonstrated to be glycoproteins by their ability to bind concanavalin A. Immunoblot analysis of yeast extracts demonstrated that anti-integrin antibodies to the human fibronectin, vitronectin and complement receptor cross-reacted with the Candida 60 kDa glycoprotein. Thus, calcium-dependent fungal cell wall glycoproteins likely related to integrins may be receptors responsible for yeast cell adherence to host tissue such as the extracellular matrix.
白色念珠菌对细胞外基质蛋白I型胶原蛋白和纤连蛋白（Fn）的黏附依赖于细胞外钙的存在。在无钙情况下，添加到I型胶原蛋白中的酵母细胞有14±3%发生黏附，而在2 mM钙存在时，62±3%的酵母细胞发生黏附。乙二胺四乙酸（EDTA）和乙二醇双四乙酸（EGTA）以剂量依赖方式降低白色念珠菌的黏附。钙以及程度稍低的铯和镁可增强酵母细胞的黏附。荧光探针铽（Tb+3）以剂量依赖方式结合到酵母细胞表面，表明酵母细胞表面存在阳离子金属结合位点。当将白色念珠菌酵母细胞提取物应用于偶联到琼脂糖的Fn或明胶柱时，白色念珠菌的两种表面蛋白可被10 mM EDTA、2%α-甲基甘露糖苷或含精氨酸-甘氨酸-天冬氨酸的肽特异性洗脱。在未还原状态下，真菌蛋白的相对分子质量分别为60,000和105,000。这些蛋白存在于细胞膜以及细胞壁中，通过其与伴刀豆球蛋白A结合的能力证明为糖蛋白。酵母提取物的免疫印迹分析表明，针对人纤连蛋白、玻连蛋白和补体受体的抗整合素抗体与念珠菌60 kDa糖蛋白发生交叉反应。因此，可能与整合素相关的钙依赖性真菌细胞壁糖蛋白可能是负责酵母细胞黏附于宿主组织如细胞外基质的受体。
