The structure of the human skin fibroblast collagenase gene

Genomic clones containing the complete gene encoding human fibroblast interstitial collagenase were isolated from a lambda phage human DNA library. The gene is comprised from 10 exons and spans 8.2 kilobase pairs. We have mapped the relative positions and determined the DNA sequence of all the exon/intron borders of the gene. The organization of the human interstitial collagenase gene is very similar to that of rabbit collagenase and of two other extracellular matrix (ECM) metalloproteases: rat stromelysin (transin) and rat transin 2. All four genes are organized into 10 exons of virtually identical size while the length of the 3' proximal introns is subject to variation. The protein sequence comprising the putative active center is coded for by exon 5 of all four genes and contains a strongly conserved zinc binding site. This observation suggests that the organization of the ECM metalloprotease genes reflect the structure of the functional domains of the enzyme proteins. The structural data accumulated so far provides evidence for the existence of a gene family coding for secreted ECM metalloproteases and suggests that gene duplication played an important role in its formation.