SIALIC ACID-DEPENDENT RECOGNITION OF LAMININ AND FIBRINOGEN BY ASPERGILLUS-FUMIGATUS CONIDIA

Citation
Jp. Bouchara et al., SIALIC ACID-DEPENDENT RECOGNITION OF LAMININ AND FIBRINOGEN BY ASPERGILLUS-FUMIGATUS CONIDIA, Infection and immunity, 65(7), 1997, pp. 2717-2724
Citations number
44
Categorie Soggetti
Immunology,"Infectious Diseases
Journal title
ISSN journal
00199567
Volume
65
Issue
7
Year of publication
1997
Pages
2717 - 2724
Database
ISI
SICI code
0019-9567(1997)65:7<2717:SAROLA>2.0.ZU;2-E
Abstract
In an attempt to define the molecular basis of the adherence of Asperg illus fumigatus conidia to the host tissues, a step which might be med iated by the recognition of basement membrane laminin or fibrinogen, w e analyzed the binding of these glycoproteins by flow cytometry and a microtiter plate adherence assay. Flow cytometry revealed that the bin ding of fluorescein isothiocyanate-labeled laminin to conidia was satu rable and specific. Moreover, the ability of conidia to bind laminin i ncreased with their maturation. Competition experiments showed a cross -reactivity between laminin and fibrinogen binding and a lack of inter actions with glycosaminoglycans. In addition, the binding of laminin w as not inhibited by the different adhesive synthetic peptides tested. Furthermore, the microtiter plate assay of adherence to chymotrypsin d egradation products of laminin or fibrinogen purified by gel filtratio n suggested a unique binding site common to sequential degradation fra gments or the presence of multiple binding sites on the two ligands. T herefore, the role of carbohydrates in the recognition process was inv estigated. Among the carbohydrates tested, constitutive of the conidia l 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 stren gthen the idea that the laminin and fibrinogen receptors in A. fumigat us are identical and suggest an interaction mediated by a sialic acid- specific lectin of the conidial wall.