sugar transferase, PEP-CTERM/EpsH1 system associated. Members of this family include a match to the pfam00534 Glycosyl transferases group 1 domain. Nearly all are found in species that encode the PEP-CTERM/exosortase system predicted to act in protein sorting in a number of Gram-negative bacteria. In particular, these transferases are found proximal to a particular variant of exosortase, EpsH1, which appears to travel with a conserved group of genes summarized by Genome Property GenProp0652. The nature of the sugar transferase reaction catalyzed by members of this clade is unknown and may conceivably be variable with respect to substrate by species, but we hypothesize a conserved substrate.

phosphatidyl-myo-inositol mannosyltransferase. This family is most closely related to the GT4 family of glycosyltransferases and named after PimA in Propionibacterium freudenreichii, which is involved in the biosynthesis of phosphatidyl-myo-inositol mannosides (PIM) which are early precursors in the biosynthesis of lipomannans (LM) and lipoarabinomannans (LAM), and catalyzes the addition of a mannosyl residue from GDP-D-mannose (GDP-Man) to the position 2 of the carrier lipid phosphatidyl-myo-inositol (PI) to generate a phosphatidyl-myo-inositol bearing an alpha-1,2-linked mannose residue (PIM1). Glycosyltransferases catalyze the transfer of sugar moieties from activated donor molecules to specific acceptor molecules, forming glycosidic bonds. The acceptor molecule can be a lipid, a protein, a heterocyclic compound, or another carbohydrate residue. This group of glycosyltransferases is most closely related to the previously defined glycosyltransferase family 1 (GT1). The members of this family may transfer UDP, ADP, GDP, or CMP linked sugars. The diverse enzymatic activities among members of this family reflect a wide range of biological functions. The protein structure available for this family has the GTB topology, one of the two protein topologies observed for nucleotide-sugar-dependent glycosyltransferases. GTB proteins have distinct N- and C- terminal domains each containing a typical Rossmann fold. The two domains have high structural homology despite minimal sequence homology. The large cleft that separates the two domains includes the catalytic center and permits a high degree of flexibility. The members of this family are found mainly in certain bacteria and archaea.

Glycosyl transferases group 1.

Glycosyltransferase involved in cell wall bisynthesis [Cell wall/membrane/envelope biogenesis].

Escherichia coli WbuB and similar proteins. This family is most closely related to the GT1 family of glycosyltransferases. WbuB in E. coli is involved in the biosynthesis of the O26 O-antigen. It has been proposed to function as an N-acetyl-L-fucosamine (L-FucNAc) transferase.