| Popis: |
Strains of Streptococcus pyogenes (group A streptococci) have the ability to express a hyaluronic acid capsule, a high molecular weight glycosaminoglycan composed of repeating subunits of glucuronic acid and N-acetylglucosamine, The polymer is synthesized by the alternate addition of UDP-glucuronic acid and UDP-N-acetylglucosamine by the streptococcal membrane-associated enzyme hyaluronate synthase. The chromosomal locus necessary for the production of the hyaluronic acid capsule, the has operon, has recently been identified and is conserved in all strains of group A streptococci and encapsulated group C streptococci3. The has operon is composed of three genes identified as hasA (hyaluronate synthase), hasB (UDP-glucose dehydrogenase), and hasC (UDP-glucose pyrophosphorylase). A single 4.1-kb mRNA product was observed by Northern blot analysis confirming that these genes are components of an operon. |
