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Infect. Immun., Jul 1997, 2717-2724, Vol 65, No. 7
JP Bouchara, M Sanchez, A Chevailler, A Marot-Leblond, JC Lissitzky, G Tronchin and D Chabasse
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.
Copyright © 1997, American Society for Microbiology
Sialic acid-dependent recognition of laminin and fibrinogen by Aspergillus fumigatus conidia
Laboratoire de Parasitologie-Mycologie, Centre Hospitalier Universitaire, Angers, France.
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