A COLLAGEN-BINDING PROTEIN PRODUCED BY AEROMONAS-HYDROPHILA

The gastrointestinal pathogen Aeromonas hydrophila strain A186 produce s a collagen-binding protein (CNBP) which is found extracellularly and loosely associated with the cell surface. The cell-associated CNBP wa s purified by sequential ammonium sulphate precipitation, size-exclusi on chromatography and ion-exchange chromatography, or by sequential am monium sulphate precipitation and affinity chromatography with collage n-Sepharose. The purified CNBP was homogeneous in SDS-PAGE, and had a mol. wt of c. 98 kDa. Cyanogen bromide cleavage of the CNBP destroyed collagen-binding activity; however, enzymic digestion with Staphylococ cus aureus V8 protease generated > 10 polypeptide fragments, from whic h a 30-kDa polypeptide contained the strongest collagen-binding activi ty. Binding of collagen by the CNBP was restricted to the a1 (I) chain of the collagen molecule and binding seemed to involve both the carbo hydrate moieties and certain peptide sequences on the collagen. Collag en-saccharides generated by alkaline hydrolysis inhibited collagen bin ding by A. hydrophila. Also, glycosidase digestion and chemical altera tion of the carbohydrate residues of collagen reduced its ability to b e bound by the CNBP. Collagen-homologous synthetic peptides inhibited binding of I-125-collagen by the bacteria.