Collagenase gene (colA) is located in the 3'-flanking region of the perfringolysin O (pfoA) locus in Clostridium perfringens.

The 3'-flanking region of the beta-galactosidase gene (pbg), which is located downstream of the perfringolysin O gene (pfoA), and the 5'-flanking region of the collagenase gene (colA) of Clostridium perfringens strains NCTC8237 and 13, respectively, were analyzed. Southern analysis revealed that the colA gene is located 6.5 kb downstream of the pbg gene in the chromosome of C. perfringens. Sequence analysis showed that between the pbg and colA genes were the arcABDC and ahrC genes, whose putative products were quite similar to enzymes of the arginine deiminase pathway of Pseudomonas aeruginosa and the arginine repressor/activator of Bacillus subtilis, respectively. It is concluded that the genomic structure of the pfoA-colA region consists of pfoR-pfoA-ORF54-pbg-arcABDC-ahrC-colA.