1r7u: Difference between revisions
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|PDB= 1r7u |SIZE=350|CAPTION= <scene name='initialview01'>1r7u</scene>, resolution 1.61Å | |PDB= 1r7u |SIZE=350|CAPTION= <scene name='initialview01'>1r7u</scene>, resolution 1.61Å | ||
|SITE= | |SITE= | ||
|LIGAND= <scene name='pdbligand=HG:MERCURY (II) ION'>HG</scene> | |LIGAND= <scene name='pdbligand=DLG:HEXYL+3-DEOXY-ALPHA-L-RIBO-HEXOPYRANOSIDE'>DLG</scene>, <scene name='pdbligand=FUC:ALPHA-L-FUCOSE'>FUC</scene>, <scene name='pdbligand=HG:MERCURY+(II)+ION'>HG</scene> | ||
|ACTIVITY= [http://en.wikipedia.org/wiki/Fucosylgalactoside_3-alpha-galactosyltransferase Fucosylgalactoside 3-alpha-galactosyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.37 2.4.1.37] | |ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Fucosylgalactoside_3-alpha-galactosyltransferase Fucosylgalactoside 3-alpha-galactosyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.37 2.4.1.37] </span> | ||
|GENE= | |GENE= | ||
|DOMAIN= | |||
|RELATEDENTRY=[[1r7t|1R7T]], [[1r7v|1R7V]], [[1r7x|1R7X]], [[1r7y|1R7Y]], [[1r80|1R80]], [[1r81|1R81]], [[1r82|1R82]] | |||
|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1r7u FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1r7u OCA], [http://www.ebi.ac.uk/pdbsum/1r7u PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1r7u RCSB]</span> | |||
}} | }} | ||
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==Overview== | ==Overview== | ||
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2)-beta-d-(3-amino)-Galp-OR, in which the 3-hydroxyl moiety of the Gal ring has been replaced by hydrogen or an amino group, respectively.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. | 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. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Palcic, M M.]] | [[Category: Palcic, M M.]] | ||
[[Category: Seto, N O.L.]] | [[Category: Seto, N O.L.]] | ||
[[Category: blood group antigen]] | [[Category: blood group antigen]] | ||
[[Category: glycoprotein]] | [[Category: glycoprotein]] | ||
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[[Category: transmembrane]] | [[Category: transmembrane]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 23:24:26 2008'' | ||
