High-affinity binding of the basement membrane protein collagen type IV to the crystalline virulence surface protein array of Aeromonas salmonicida |
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| Authors: | Trevor J Trust Magdalena Kostrzynska Levente Emödy Torkel Wadström |
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| Institution: | Department of Biochemistry and Microbiology, and Canadian Bacterial Diseases Network, University of Victoria, Victoria, British Columbia, V8W3P6, Canada.;Institute of Microbiology, University Medical School, Pécs, Hungary.;Institute of Medical Microbiology, University of Lund, Lund, Sweden. |
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| Abstract: | 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. |
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