Protein Family Models

Date:

2024-08-14

This Pfam family represents a conserved region from a number of different bacterial sugar transferases, involved in diverse biosynthesis pathways. [1]. 9423846. Identification of a genetic locus essential for serotype b-specific antigen synthesis in Actinobacillus actinomycetemcomitans. Yoshida Y, Nakano Y, Yamashita Y, Koga T;. Infect Immun 1998;66:107-114. (from Pfam)

Date:

2024-10-16

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.

Date:

2021-08-23

The WbaP (formerly RfbP) protein has been characterized [1,2] as the first enzyme in O-antigen biosynthesis in Salmonella typhimurium. The enzyme transfers galactose from UDP-galactose to a polyprenyl carrier (utilizing the highly conserved C-terminal sugar transferase domain, PF02397) a reaction which takes place at the cytoplasmic face of the inner membrane. The N-terminal hydrophobic domain is then believed to facilitate the "flippase" function of transferring the liposaccharide unit from the cytoplasmic face to the periplasmic face of the inner membrane. This model includes the enterobacterial enzymes, where the function is presumed to be identical to the S. typhimurium enzyme as well as a somewhat broader group which are likely to catalyze the same or highly similar reactions based on a phylogenetic tree-building analysis of the broader sugar transferase family. Most of these genes are found within large operons dedicated to the production of complex exopolysaccharides such as the enterobacterial O-antigen. The most likely heterogeneity would be in the precise nature of the sugar molecule transferred.

Gene:

wbaP

Date:

2024-05-30