Glycosyltransferase family 52. This family features glycosyltransferases belonging to glycosyltransferase family 52, which have alpha-2,3- sialyltransferase (EC:4.2.99.4) and alpha-glucosyltransferase (EC 2.4.1.-) activity. For example, beta-galactoside alpha-2,3- sialyltransferase expressed by Neisseria meningitidis is a member of this family and is involved in a step of lipooligosaccharide biosynthesis requiring sialic acid transfer; these lipooligosaccharides are thought to be important in the process of pathogenesis. This family includes several bacterial lipooligosaccharide sialyltransferases similar to the Haemophilus ducreyi LST protein. Haemophilus ducreyi is the cause of the sexually transmitted disease chancroid and produces a lipooligosaccharide (LOS) containing a terminal sialyl N-acetyllactosamine trisaccharide.
Alpha-2,8-polysialyltransferase (POLYST). This family contains the bacterial enzyme alpha-2,8-polysialyltransferase (EC:2.4.99.-) (approximately 500 residues long). This catalyzes the polycondensation of alpha-2,8-linked sialic acid required for the synthesis of polysialic acid (PSA).
acyl-CoA synthetase family member 4. This family of the adenylation (A) domain of nonribosomal peptide synthases (NRPS) contains acyl-CoA synthethase family member 4, also known as 2-aminoadipic 6-semialdehyde dehydrogenase or aminoadipate-semialdehyde dehydrogenase, most of which are uncharacterized. Acyl-CoA synthetase catalyzes the initial reaction in fatty acid metabolism, by forming a thioester with CoA. NRPSs are large multifunctional enzymes which synthesize many therapeutically useful peptides in bacteria and fungi via a template-directed, nucleic acid independent nonribosomal mechanism. These natural products include antibiotics, immunosuppressants, plant and animal toxins, and enzyme inhibitors. NRPS has a distinct modular structure in which each module is responsible for the recognition, activation, and in some cases, modification of a single amino acid residue of the final peptide product. The modules can be subdivided into domains that catalyze specific biochemical reactions.
