Production and secretion of collagen-binding proteins from Aeromonas veronii

Collagen-binding protein (CNBP) synthesized by Aeromonas veronii is located conserved within the subcellular fraction. The results of this study show that 98% of the total CNBP produced by Aer. veronii is present in the extra cellular medium, and that the remaining CNBP is distributed either on the c ell surface, within the periplasm or anchored on the outer membrane. CNBP i s specifically secreted from Aer. veronii into the culture medium, because all the beta -lactamase activity was located in the cells and could be rele ased by polymixin B extraction of periplasmic proteins. CNBP was produced a t growth temperatures from 12 degreesC to 42 degreesC, but not at 4 degrees C. The findings indicate that the level of CNBP in the medium increases dur ing the exponential growth phase and reaches a maximum during the early sta tionary phase. There was less CNBP production in poor nutrient MMB medium t han in the rich LB nutrient medium. CNBP secretion, in contrast to aerolysi n secretion, was unaffected by the exeA mutation of Aer. hydrophila. It is concluded that CNBP secretion from Aer. veronii must be achieved by a mecha nism different from that reported for aerolysin secretion.