N,N'-diacetylbacillosaminyl-diphospho-undecaprenol alpha-1,3-N-acetylgalactosaminyltransferase explained

N,N'-diacetylbacillosaminyl-diphospho-undecaprenol alpha-1,3-N-acetylgalactosaminyltransferase
Ec Number:	2.4.1.290

N,N'-diacetylbacillosaminyl-diphospho-undecaprenol alpha-1,3-N-acetylgalactosaminyltransferase (PglA) is an enzyme with systematic name UDP-N-acetyl-alpha-D-galactosamine:N,N'-diacetyl-alpha-D-bacillosaminyl-diphospho-tritrans,heptacis-undecaprenol 3-alpha-N-acetyl-D-galactosaminyltransferase.^[1] This enzyme catalyses the following chemical reaction

UDP-N-acetyl-alpha-D-galactosamine + N,N'-diacetyl-alpha-D-bacillosaminyl-diphospho-tritrans,heptacis-undecaprenol

\rightleftharpoons UDP + N-acetyl-D-galactosaminyl-alpha-(1->3)-N,N'-diacetyl-alpha-D-bacillosaminyl-diphospho-tritrans,heptacis-undecaprenol

This enzyme is isolated from Campylobacter jejuni. It is important for N-linked glycosylation in this species.^[2] The glycosyl motif that the enzymes encoded by the Pgl locus create consists of a bacillosamine joined to a GalNAc residue by an alpha 1–3 glycosidic bond, followed by four additional GalNAc residues linked by alpha 1–4 bonds. A branching glucose residue completes the heptasaccharide, joined by a beta 1–3 linkage to the third GalNAc residue from the amino acid linkage point.^[3] Glycosylation takes place on an undecaprenyl pyrophosphate on the cytosolic face of the plasma membrane, followed by flippase transfer to the periplasmic space and en bloc transfer to an asparagine residue.^[4]

This enzyme catalyzes the addition of GalNAc, covalently bonded to carrier uridine diphosphate (UDP), to isoprenoid lipid–linked bacillosamine, resulting in production of UDP and the glycosylated lipid.^[1]

Notes and References

1. Glover KJ, Weerapana E, Imperiali B . In vitro assembly of the undecaprenylpyrophosphate-linked heptasaccharide for prokaryotic N-linked glycosylation . Proceedings of the National Academy of Sciences of the United States of America . 102 . 40 . 14255–9 . October 2005 . 16186480 . 1242339 . 10.1073/pnas.0507311102 . 2005PNAS..10214255G . free .
2. Karlyshev AV, Ketley JM, Wren BW. The Campylobacter jejuni Glycome. FEMS Microbiology Reviews. 29. 2. 377-390. 10.1016/j.fmrre.2005.01.003. free. 15808749. 2005.
3. Young NM, Brisson JR, Kelly J, Watson DC, Tessier L, Lanthier PH, Jarrell HC, Cadotte N, St Michael F, Aberg E, Szymanski CM. Structure of the N-linked glycan present on multiple glycoproteins in the Gram-negative bacterium, Campylobacter jejuni. Journal of Biological Chemistry. 277. 45. 42530-42539. 2002. 10.1074/jbc.M206114200. free. 12186869.
4. Alaimo C, Catrein I, Morf L, Marolda CL, Callewaert N, Valvano MA, Feldman MF, Aebi M. Two distinct but interchangeable mechanisms for flipping of lipid-linked oligosaccharides. The EMBO Journal. 25. 5. 967-976. 2006. 10.1038/sj.emboj.7601024. free. 16498400. 1409731.