N-terminal domain of Chondroitin polymerase functions as a GalNAc transferase.
Chondroitin polymerase is a two domain, bi-functional protein. The N-terminal domain functions as a GalNAc transferase. The bacterial chondroitin polymerase catalyzes elongation of the chondroitin chain by alternatively transferring the GlcUA and GalNAc moiety from UDP-GlcUA and UDP-GalNAc to the non-reducing ends of the chondroitin chain. The enzyme consists of N-terminal and C-terminal domains in which the two active sites catalyze the addition of GalNAc and GlcUA, respectively. Chondroitin chains range from 40 to over 100 repeating units of the disaccharide. Sulfated chondroitins are involved in the regulation of various biological functions such as central nervous system development, wound repair, infection, growth factor signaling, and morphogenesis, in addition to its conventional structural roles. In Caenorhabditis elegans, chondroitin is an essential factor for the worm to undergo cytokinesis and cell division. Chondroitin is synthesized as proteoglycans, sulfated and secreted to the cell surface or extracellular matrix.