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 (PF02397). Characterized and partially characterized members of this subfamily include Salmonella WbaP (originally RfbP) [1], E. coli WcaJ [2], Methylobacillus EpsB [3], Xanthomonas GumD [4], Vibrio CpsA [5], Erwinia AmsG [6], Group B Streptococcus CpsE (originally CpsD) [7], and Streptococcus suis Cps2E [8]. 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 [9] and Lactococcus EpsD [10] lack the N-terminal domain and are not found by this model.
GO Terms:- Date:
- 2021-08-23