Molecular and functional characterization of channel catfish (Ictalurus punctatus) neutrophil collagenase

Abstract

Channel catfish (Ictalurus punctatus) neutrophils, like mammalian neutrophils, contain a variety of enzymes and lytic peptides that participate in pathogen destruction. We have identified and characterized from a channel catfish anterior kidney cDNA library a 1.6 kb cDNA that encodes for channel catfish neutrophil collagenase. The deduced amino acid sequence has a predicted molecular mass of 53 kDa. The putative catfish collagenase has nucleotide and amino acid homology of 51.4% and 45.1%, respectively, with human neutrophil collagenase and 50.4% and 47.1%, respectively, with mouse neutrophil collagenase. Certain regions of the molecule, including the cysteine switch and the putative zinc binding sites, were identical to those in the human and mouse genes. Polyclonal antiserum, prepared to the fusion protein, recognizes proteins from channel catfish neutrophil supernatants with molecular masses of approximately 63, 53 and 28 kDa. Supernatants from phorbol dibutyrate stimulated neutrophils were capable of degrading type I collagen. In addition, the polyclonal antiserum prevented the collagenase activity of the supernatants from stimulated catfish neutrophils; whereas, preimmune serum had no effect on collagenase activity of supernatants. Supernatants from unstimulated cells or the fusion protein did not possess the ability of degrading type I collagen. These results indicate that channel catfish neutrophil collagenases share molecular and functional features with mammalian neutrophil collagenase.