Group A and C streptococci have the ability to surround themselves with a capsule formed by hyaluronic acid (HA) which serves as a virulence factor. The structure of streptococcal HA is identical to mammalian HA where it is a ubiquitous component of connective tissue. HA is also synthesized and secreted by many differentiated cells in the body and plays a role in the morphogenesis of embryonic tissue, the invasiveness of carcinoma cells, and virus transformation of fibroblasts and chondrocytes. Finally, deregulation of the synthesis of HA appears to play an important role in Marfans syndrome and osteogenesis imperfecta. Therefore an examination of the mode of synthesis of this biological molecules is required in order to understand its role in the above processes. The cell free synthesis of HA was demonstrated in 1955 but attempts at solubilization of the synthetase have all failed until recently. Our laboratory is the first group to solubile the HA synthetase with its enzymatic activity intact. Furthermore, a requirement for phospholipid was demonstrated for both reactivation and enhancement of the enzsymatic activity. The overall objective of this proposal is to purify and characterize the HA synthetase from streptococci. Toward this objective we plan to isolate the streptococcal enzyme using affinity chromatography and specific probes. In addition the synthetase will be cloned into E. coli to engineer an overproducer of the synthetase. As the synthetase is isolated it will be characterized as to its physical properties, phospholipid requirements, substrate kinetics, size of product, role of primer, and location of addition of monosaccharides (reducing or nonreducing end). The completion of these specific aim should provide us with the information to understand the regulation of the production of this molecule in procaryote cells. Finally, these studies should add information useful in understanding the role of this molecule as a virulence factor in the poststreptococcal sequelae (acute rheumatic fever, glomerulonephritis) and its deregulation in such disease states as Marfans syndrome, osteogenesis imperfecta, and cancer.
| van de Rijn, I; Drake, R R (1992) Analysis of the streptococcal hyaluronic acid synthase complex using the photoaffinity probe 5-azido-UDP-glucuronic acid. J Biol Chem 267:24302-6 |
| Dougherty, B A; van de Rijn, I (1992) Molecular characterization of a locus required for hyaluronic acid capsule production in group A streptococci. J Exp Med 175:1291-9 |
| Triscott, M X; van de Rijn, I (1986) Solubilization of hyaluronic acid synthetic activity from streptococci and its activation with phospholipids. J Biol Chem 261:6004-9 |
