Streptococcal hyaluronic acid: proposed mechanisms of degradation and loss of synthesis during stationary phase

Abstract

Streptococcal hyaluronic acid was found to distribute into two discrete sizes. Cellular hyaluronic acid from strain D181 had an average molecular weight of 10 X 10(6), whereas the average molecular weight of extracellular hyaluronic acid from the same strain was 2 X 10(6). Cellular streptococcal hyaluronic acid was purified to homogeneity. Proteases were unable to cleave the purified cellular polymer, indicating that a peptide was not involved in cross-linking five extracellular hyaluronate polymers to form a cell-bound complex. Lipids apparently are not part of the cellular hyaluronic acid because phosphorus and glycerol were not detected by radioisotopic techniques, and denaturing conditions did not change the size of the polymer. Membranes obtained from various strains of group A and C streptococci cleaved the cellular form of the hyaluronate polymer demonstrating the presence of a membrane-bound hyaluronidase-like activity. By contrast, this activity was not found in the extracellular products of the strains studied. Furthermore, membranes derived from streptococci at the stationary phase of growth no longer had the capacity to synthesize hyaluronic acid. The loss of this property appeared to be due to changes in the structure of the membrane.