MOLECULAR-GENETIC ANALYSIS OF THE NAGH GENE ENCODING A HYALURONIDASE OF CLOSTRIDIUM-PERFRINGENS

A recombinant lambda phage was identified in a Clostridium perfringens genomic library by means of its ability to hydrolyse the fluorescent substrate 4-methyl-umbelliferyl-beta-D-glucosaminide, isolated and sho wn to encode an endo-beta-N-acetylglucosaminidase. This enzyme, NagH, is also known as hyaluronidase, or Mu toxin, a putative virulence fact or which is likely to act on connective tissue during gas gangrene. Nu cleotide sequence analysis allowed the primary structure to be deduced and showed hyaluronidase to be a large exported protein of 114392 Dal tons and an enzyme of this size, endowed with the corresponding activi ties, was partially purified from C. perfringens. Hyaluronidase seems to be organised into two domains, an N-terminal region comprising 700 amino acids bearing the active site and a 300-residue C-terminal segme nt, containing three copies of an extended motif. Two other reading fr ames, linked to nagH, also appear to encode proteins with sugar-bindin g motifs.