Gene duplication and multiplicity of collagenases in Clostridium histolyticum

Clostridium histolyticum collagenase contains a number of different active components. Previously we have shown that colH encodes a 116-kDa collagenase (ColH) and a 98-kDa gelatinase. We purified a different 116-kDa collagenase (ColG) from the culture supernatant and sequenced its gene (colG). We also identified four other gelatinases (105, 82, 78, and 67 kDa) and determined their N-terminal amino acid sequences, all of which coincided with that of either ColG or ColH. Hybridization experiments showed that each gene is present in a single copy and each gene is transcribed into a single mRNA. These results suggest that all the gelatinases are produced from the respective full-length collagenase by the proteolytic removal of C-terminal fragments. The substrate specificities of the enzymes suggest that colG and colH encode class I and class II enzymes, respectively. Analysis of their DNA locations by pulsed-field gel electrophoresis and nucleotide sequencing of their surrounding regions revealed that the two genes are located in different sites on the chromosome. C. histolyticum colG is more similar to C. perfringens colA than to colH in terms of domain structure. Both colG and colA have a homologous gene, mscL, at their 3' ends. These results suggest that gene duplication and segment duplication have occurred in an ancestor cell common to C. histolyticum and C. perfringens and that further divergence of the parent gene produced colG and colA.