Alonso Ruth, Llopis Inés, Flores Consuelo, Murgui Amelia, Timoneda Joaquı N
Secció Departamental de Bioquı́mica i Biologia Molecular, Facultat de Farmacia, Universitat de Valencia, Avda Vicent A. Estellés, s/n, 46100-Burjassot (València), Spain1.
Departamento de Bioquı́mica, Facultad de Estomatologı́a, Benemérita Universidad autónoma de Puebla, Mexico2.
Microbiology (Reading). 2001 Jul;147(Pt 7):1971-1981. doi: 10.1099/00221287-147-7-1971.
Adherence of the opportunistic pathogen Candida albicans to basement membrane (BM) proteins is considered a crucial step in the development of candidiasis. In this study the interactions of C. albicans yeast cells with the three main domains of type IV collagen, a major BM glycoprotein, were analysed. C. albicans adhered to the three immobilized domains by different mechanisms. Adhesion to the N-terminal cross-linking domain (7S) required the presence of divalent cations, whereas interaction with the central collagenous domain (CC) was cation-independent. Recognition of the C-terminal non-collagenous domain (NC1) was partially cation-dependent. Binding inhibition assays with the corresponding domains in soluble form showed that these interactions were specific. Both Ca(2+) and Mg(2+) promoted adhesion to the 7S domain and the interaction was completely abolished by EDTA. Treatment of the 7S domain, or its subunits, with N-glycosidase F reduced yeast binding by approximately 70%. Moreover, several sugars known to be part of the N-linked oligosaccharide chains of collagen IV inhibited adhesion to immobilized 7S; N-acetylglucosamine, L-fucose and methylmannoside caused a similar inhibition whereas N-acetyllactosamine was a more effective inhibitor. In contrast, glucose, galactose, lactose or heparan sulfate did not affect yeast binding. Combinations of the inhibitory sugars at suboptimal inhibition concentrations did not reduce C. albicans adhesion more than the individual sugars, pointing to a single lectin as responsible for the interaction. These results taken together show that C. albicans utilizes several adhesins for interacting with type IV collagen, and that at least one of them is a lectin which recognizes the 7S(IV) oligosaccharide residues as its receptor.
机会性病原体白色念珠菌与基底膜（BM）蛋白的黏附被认为是念珠菌病发展中的关键步骤。在本研究中，分析了白色念珠菌酵母细胞与主要BM糖蛋白IV型胶原蛋白的三个主要结构域之间的相互作用。白色念珠菌通过不同机制黏附于这三个固定化结构域。黏附于N端交联结构域（7S）需要二价阳离子的存在，而与中央胶原结构域（CC）的相互作用则不依赖阳离子。对C端非胶原结构域（NC1）的识别部分依赖阳离子。用可溶性形式的相应结构域进行的结合抑制试验表明，这些相互作用是特异性的。Ca(2+)和Mg(2+)均促进对7S结构域的黏附，而EDTA可完全消除这种相互作用。用N-糖苷酶F处理7S结构域或其亚基可使酵母结合减少约70%。此外，几种已知为IV型胶原N-连接寡糖链组成部分的糖类可抑制对固定化7S的黏附；N-乙酰葡糖胺、L-岩藻糖和甲基甘露糖苷引起类似的抑制作用，而N-乙酰乳糖胺是更有效的抑制剂。相比之下，葡萄糖、半乳糖、乳糖或硫酸乙酰肝素不影响酵母结合。次优抑制浓度的抑制性糖类组合对白色念珠菌黏附的降低作用并不比单个糖类更大，表明负责这种相互作用的是单一凝集素。这些结果共同表明，白色念珠菌利用多种黏附素与IV型胶原相互作用，并且其中至少一种是识别7S(IV)寡糖残基作为其受体的凝集素。
