title: Sialic acid-dependent recognition of laminin and fibrinogen by Aspergillus fumigatus conidia.
abstract: In an attempt to define the molecular basis of the adherence of Aspergillus fumigatus conidia to the host tissues, a step which might be mediated by the recognition of basement membrane laminin or fibrinogen, we analyzed the binding of these glycoproteins by flow cytometry and a microtiter plate adherence assay. Flow cytometry revealed that the binding of fluorescein isothiocyanate-labeled laminin to conidia was saturable and specific. Moreover, the ability of conidia to bind laminin increased with their maturation. Competition experiments showed a cross-reactivity between laminin and fibrinogen binding and a lack of interactions with glycosaminoglycans. In addition, the binding of laminin was not inhibited by the different adhesive synthetic peptides tested. Furthermore, the microtiter plate assay of adherence to chymotrypsin degradation products of laminin or fibrinogen purified by gel filtration suggested a unique binding site common to sequential degradation fragments or the presence of multiple binding sites on the two ligands. Therefore, the role of carbohydrates in the recognition process was investigated. Among the carbohydrates tested, constitutive of the conidial wall or of the oligosaccharide side chains of laminin and fibrinogen, only N-acetylneuraminic acid and sialyllactose inhibited the binding of these glycoproteins to conidia. In conclusion, these results strengthen the idea that the laminin and fibrinogen receptors in A. fumigatus are identical and suggest an interaction mediated by a sialic acid-specific lectin of the conidial wall.
authors.affiliation: Laboratoire de Parasitologie-Mycologie, Centre Hospitalier Universitaire, Angers, France.
authors.forename: J P
authors.initials: JP
authors.lastname: Bouchara
authors.forename: M
authors.initials: M
authors.lastname: Sanchez
authors.forename: A
authors.initials: A
authors.lastname: Chevailler
authors.forename: A
authors.initials: A
authors.lastname: Marot-Leblond
authors.forename: J C
authors.initials: JC
authors.lastname: Lissitzky
authors.forename: G
authors.initials: G
authors.lastname: Tronchin
authors.forename: D
authors.initials: D
authors.lastname: Chabasse
mesh_terms: D001232:Aspergillus fumigatus / Q000276:immunology*; D002918:Chymotrypsin / Q000494:pharmacology; D003429:Cross Reactions; D005340:Fibrinogen / Q000276:immunology*; D005353:Fibronectins / Q000276:immunology; D005434:Flow Cytometry; D007797:Laminin / Q000276:immunology*; D019158:N-Acetylneuraminic Acid / Q000502:physiology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000032:analysis; D017474:Receptors, Laminin / Q000032:analysis
chemical_list: D005353:Fibronectins; D007797:Laminin; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D017474:Receptors, Laminin; D005340:Fibrinogen; D002918:Chymotrypsin; D019158:N-Acetylneuraminic Acid