High-affinity binding of the basement membrane protein collagen type IV to the crystalline virulence surface protein array of Aeromonas salmonicida

• Published in: Molecular microbiology Vol. 7; no. 4; p. 593
• Main Authors: Trust, T J, Kostrzynska, M, Emödy, L, Wadström, T
• Format: Journal Article
• Language: English
• Published: England 01.02.1993
• Subjects: Aeromonas - metabolism; Aeromonas - pathogenicity; Bacterial Adhesion - physiology; Bacterial Proteins - metabolism; Basement Membrane - metabolism; Binding, Competitive; Collagen - metabolism; Membrane Proteins - metabolism; Virulence
• ISSN: 0950-382X
• DOI: 10.1111/j.1365-2958.1993.tb01150.x

The surface of the fish pathogen Aeromonas salmonicida is covered by a paracrystalline array (the A-layer) which is a virulence factor for the organism. Quantification of the ability of A. salmonicida cells to bind collagen types I and IV in a 125I-radiolabelled liquid-phase assay showed that A-layer-positive cells bound high levels of collagen type IV, but significantly lower levels of collagen type I. Collagen type IV binding was confirmed using non-radiolabelled enzyme-linked immunosorbent assays. 125I-Collagen type IV binding was rapid, specific, saturable, high affinity, and essentially irreversible by unlabelled collagen type IV. The A-layer was responsible for collagen type IV binding because binding was inactivated by selective removal of the A-layer at pH 2.2, and neither isogenic A-layer-deficient A. salmonicida mutants nor strains of Aeromonas hydrophila possessing a morphologically similar paracrystalline array bound this basement membrane protein.