Different adhesins for type IV collagen on Candida albicans: identification of a lectin-like adhesin recognizing the 7S(IV) domain

Adherence of the opportunistic pathogen Candida albicans to basement membra ne (BM) proteins is considered a crucial step in the development of candidi asis. In this study the interactions of C. albicans yeast cells with the th ree main domains of type IV collagen, a major BM glycoprotein, were analyse d. C. albicans adhered to the three immobilized domains by different mechan isms. Adhesion to the N-terminal cross-linking domain (7S) required the pre sence of divalent cations, whereas interaction with the central collagensus domain (CC) was cation-independent. Recognition of the C-terminal noncolla genous domain (NCI) was partially cation-dependent. Binding inhibition assa ys with the corresponding domains in soluble form showed that these interac tions were specific. Both Ca2+ and Mg2+ promoted adhesion to the 75 domain and the interaction was completely abolished by EDTA. Treatment of the 75 d omain, or its subunits, with N-glycosidase F reduced yeast binding by appro ximately 70%. Moreover, several sugars known to be part of the N-linked oli gosaccharide 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, g lucose, galactose, lactase or heparan sulfate did not affect yeast binding. Combinations of the inhibitory sugars at suboptimal inhibition concentrati ons did not reduce C. albicans adhesion snore than the individual sugars, p ointing to a single lectin as responsible for the interaction. These result s taken together show that C. albicans utilizes several adhesins for intera cting with type IV collagen, and that at least one of them is a lectin whic h recognizes the 75(IV) oligosaccharide residues as its receptor.