First time at Proteopedia? Click on the green links: they change the 3D image. Click and drag the molecules. Proteopedia is a 3D, interactive encyclopedia of proteins, RNA, DNA and other molecules. With a free user account, you can edit pages in Proteopedia. Visit the Main Page to learn more.

1r7u

From Proteopedia

Jump to: navigation, search


1r7u, resolution 1.61Å ()
Ligands: , ,
Activity: Fucosylgalactoside 3-alpha-galactosyltransferase, with EC number 2.4.1.37
Related: 1r7t, 1r7v, 1r7x, 1r7y, 1r80, 1r81, 1r82
Resources: FirstGlance, OCA, PDBsum, RCSB
Coordinates: save as pdb, mmCIF, xml



Contents

Glycosyltransferase B in complex with 3-deoxy-acceptor analog inhibitor

Publication Abstract from PubMed

Human ABO(H) blood group glycosyltransferases GTA and GTB catalyze the final monosaccharide addition in the biosynthesis of the human A and B blood group antigens. GTA and GTB utilize a common acceptor, the H antigen disaccharide alpha-l-Fucp-(1-->2)-beta-d-Galp-OR, but different donors, where GTA transfers GalNAc from UDP-GalNAc and GTB transfers Gal from UDP-Gal. GTA and GTB are two of the most homologous enzymes known to transfer different donors and differ in only 4 amino acid residues, but one in particular (Leu/Met-266) has been shown to dominate the selection between donor sugars. The structures of the A and B glycosyltransferases have been determined to high resolution in complex with two inhibitory acceptor analogs alpha-l-Fucp(1-->2)-beta-d-(3-deoxy)-Galp-OR and alpha-l-Fucp-(1-->2)-beta-d-(3-amino)-Galp-OR, in which the 3-hydroxyl moiety of the Gal ring has been replaced by hydrogen or an amino group, respectively. Remarkably, although the 3-deoxy inhibitor occupies the same conformation and position observed for the native H antigen in GTA and GTB, the 3-amino analog is recognized differently by the two enzymes. The 3-amino substitution introduces a novel intramolecular hydrogen bond between O2' on Fuc and N3' on Gal, which alters the minimum-energy conformation of the inhibitor. In the absence of UDP, the 3-amino analog can be accommodated by either GTA or GTB with the l-Fuc residue partially occupying the vacant UDP binding site. However, in the presence of UDP, the analog is forced to abandon the intramolecular hydrogen bond, and the l-Fuc residue is shifted to a less ordered conformation. Further, the residue Leu/Met-266 that was thought important only in distinguishing between donor substrates is observed to interact differently with the 3-amino acceptor analog in GTA and GTB. These observations explain why the 3-deoxy analog acts as a competitive inhibitor of the glycosyltransferase reaction, whereas the 3-amino analog displays complex modes of inhibition.

The influence of an intramolecular hydrogen bond in differential recognition of inhibitory acceptor analogs by human ABO(H) blood group A and B glycosyltransferases., Nguyen HP, Seto NO, Cai Y, Leinala EK, Borisova SN, Palcic MM, Evans SV, J Biol Chem. 2003 Dec 5;278(49):49191-5. Epub 2003 Sep 11. PMID:12972418

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

About this Structure

1r7u is a 1 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA.

See Also

Reference

  • Nguyen HP, Seto NO, Cai Y, Leinala EK, Borisova SN, Palcic MM, Evans SV. The influence of an intramolecular hydrogen bond in differential recognition of inhibitory acceptor analogs by human ABO(H) blood group A and B glycosyltransferases. J Biol Chem. 2003 Dec 5;278(49):49191-5. Epub 2003 Sep 11. PMID:12972418 doi:http://dx.doi.org/10.1074/jbc.M308770200

Proteopedia Page Contributors and Editors (what is this?)

OCA

Personal tools