lipopolysaccharide heptosyltransferase and similar proteins. Lipopolysaccharide heptosyltransferase (2.4.99.B6) is involved in the biosynthesis of lipooligosaccharide (LOS). Lipopolysaccharide (LPS) is a major component of the outer membrane of gram-negative bacteria. LPS heptosyltransferase transfers heptose molecules from ADP-heptose to 3-deoxy-D-manno-octulosonic acid (KDO), a part of the inner core component of LPS. This family also contains lipopolysaccharide 1,2-N-acetylglucosaminetransferase EC 2.4.1.56 and belongs to the GT-B structural superfamily of glycoslytransferases, which have characteristic 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.
Glycosyltransferase family 9 (heptosyltransferase). Members of this family belong to glycosyltransferase family 9. Lipopolysaccharide is a major component of the outer leaflet of the outer membrane in Gram-negative bacteria. It is composed of three domains; lipid A, Core oligosaccharide and the O-antigen. All of these enzymes transfer heptose to the lipopolysaccharide core.
The glycosyltransferase WecG/TagA superfamily contains Escherichia coli WecG, Bacillus subtilis TagA and related proteins. E. coli WecG is believed to be a UDP-N-acetyl-D-mannosaminuronic acid transferase, and is involved in enterobacterial common antigen (eca) synthesis. B. subtilis TagA plays a key role in the Wall Teichoic Acid (WTA) biosynthetic pathway, catalyzing the transfer of N-acetylmannosamine to the C4 hydroxyl of a membrane-anchored N-acetylglucosaminyl diphospholipid to make ManNAc-beta-(1,4)-GlcNAc-pp-undecaprenyl. This is the first committed step in this pathway. Also included in this group is Xanthomonas campestris pv. campestris GumM, a glycosyltransferase participating in the biosynthesis of the exopolysaccharide xanthan.