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.

Lipopolysaccharide heptosyltransferase 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 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.

lipopolysaccharide heptosyltransferase I. This family consists of examples of ADP-heptose:LPS heptosyltransferase I, an enzyme of LPS inner core region biosynthesis. LPS, composed of lipid A, a core region, and O antigen, is found in the outer membrane of Gram-negative bacteria [Cell envelope, Biosynthesis and degradation of surface polysaccharides and lipopolysaccharides].

ADP-heptose:LPS heptosyltransferase [Cell envelope biogenesis, outer membrane]