MOLECULAR POPULATION GENETIC-ANALYSIS OF A STREPTOCOCCUS-PYOGENES BACTERIOPHAGE-ENCODED HYASURONIDASE GENE - RECOMBINATION CONTRIBUTES TO ALLELIC VARIATION

Many strains of the human pathogenic bacterium Streptococcus pyogenes produce hyaluronidase, an enzyme that degrades hyaluronic acid, a majo r component of the extracellular matrix. Degradation of hyaluronic aci d is thought to aid in host tissue invasion and dissemination of S. py ogenes. The molecular population genetics of the bacteriophage-encoded hyaluronidase gene (hyl) was analysed by sequencing the gene from 13 streptococcal strains representing seven well-differentiated multilocu s enzyme electrophoretic types and eight M or T protein serotypes. Sub stantial levels of allelic polymorphism were identified, and the analy sis found strong statistical evidence that recombinational processes h ave contributed to the generation of molecular variation in this gene. A 111 base pair segment of hyl encoding a collagenous motif, that may bind collagen, was absent in a serotype M14 isolate and 13 serotype M 18 multilocus enzyme electrophoretic type 20 strains examined. The ana lysis provides a molecular population genetics framework for studies e xamining the role of naturally occurring hyaluronidase variation in ho st-pathogen interactions. (C) 1997 Academic Press Limited.