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exopolysaccharide biosynthesis polyprenyl glycosylphosphotransferase Members of this family are generally found near other genes involved in the biosynthesis of a variety of exopolysaccharides. These proteins consist of two fused domains, an N-terminal hydrophobic domain of generally low conservation and a highly conserved C-terminal sugar transferase domain (pfam02397). Characterized and partially characterized members of this subfamily include Salmonella WbaP (originally RfbP), E. coli WcaJ, Methylobacillus EpsB, Xanthomonas GumD, Vibrio CpsA, Erwinia AmsG, Group B Streptococcus CpsE (originally CpsD), and Streptococcus suis Cps2E. Each of these is believed to act in transferring the sugar from, for instance, UDP-glucose or UDP-galactose, to a lipid carrier such as undecaprenyl phosphate as the first (priming) step in the synthesis of an oligosaccharide "block". This function is encoded in the C-terminal domain. The liposaccharide is believed to be subsequently transferred through a "flippase" function from the cytoplasmic to the periplasmic face of the inner membrane by the N-terminal domain. Certain closely related transferase enzymes, such as Sinorhizobium ExoY and Lactococcus EpsD, lack the N-terminal domain and are not found by this model. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",