Linked Life Data

15449940

Source:http://linkedlifedata.com/resource/pubmed/id/15449940

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
39
pubmed:dateCreated
2004-9-28
pubmed:databankReference
pubmed:abstractText
Beta-1,4-galactosyltransferase (beta4Gal-T1) in the presence of manganese ion transfers galactose from UDP-galactose (UDP-Gal) to N-acetylglucosamine (GlcNAc) that is either free or linked to an oligosaccharide. Crystallographic studies on bovine beta4Gal-T1 have shown that the primary metal binding site is located in the hinge region of a long flexible loop, which upon Mn(2+) and UDP-Gal binding changes from an open to a closed conformation. This conformational change creates an oligosaccharide binding site in the enzyme. Neither UDP nor UDP analogues efficiently induce these conformational changes in the wild-type enzyme, thereby restricting the structural analysis of the acceptor binding site. The binding of Mn(2+) involves an uncommon coordination to the Sdelta atom of Met344; when it is mutated to His, the mutant M344H, in the presence of Mn(2+) and UDP-hexanolamine, readily changes to a closed conformation, facilitating the structural analysis of the enzyme bound with an oligosaccharide acceptor. Although the mutant M344H loses 98% of its Mn(2+)-dependent activity, it exhibits 25% of its activity in the presence of Mg(2+). The crystal structures of M344H-Gal-T1 in complex with either UDP-Gal.Mn(2+) or UDP-Gal.Mg(2+), determined at 2.3 A resolution, show that the mutant enzyme in these complexes is in a closed conformation, and the coordination stereochemistry of Mg(2+) is quite similar to that of Mn(2+). Although either Mn(2+) or Mg(2+), together with UDP-Gal, binds and changes the conformation of the M344H mutant to the closed one, it is the Mg(2+) complex that engages efficiently in catalyses. Thus, this property enabled us to crystallize the M344H mutant for the first time with the acceptor substrate chitobiose in the presence of UDP-hexanolamine and Mn(2+). The crystal structure determined at 2.3 A resolution reveals that the GlcNAc residue at the nonreducing end of chitobiose makes extensive hydrophobic interactions with the highly conserved Tyr286 residue.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
43
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12513-22
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:15449940-Acetylglucosamine, pubmed-meshheading:15449940-Animals, pubmed-meshheading:15449940-Carbohydrate Conformation, pubmed-meshheading:15449940-Catalysis, pubmed-meshheading:15449940-Cattle, pubmed-meshheading:15449940-Crystallization, pubmed-meshheading:15449940-Crystallography, X-Ray, pubmed-meshheading:15449940-Disaccharides, pubmed-meshheading:15449940-Hexanes, pubmed-meshheading:15449940-Histidine, pubmed-meshheading:15449940-Magnesium, pubmed-meshheading:15449940-Manganese, pubmed-meshheading:15449940-Methionine, pubmed-meshheading:15449940-Monosaccharides, pubmed-meshheading:15449940-Mutagenesis, Site-Directed, pubmed-meshheading:15449940-N-Acetyllactosamine Synthase, pubmed-meshheading:15449940-Protein Conformation, pubmed-meshheading:15449940-Structure-Activity Relationship, pubmed-meshheading:15449940-Thermodynamics, pubmed-meshheading:15449940-Tyrosine, pubmed-meshheading:15449940-Uridine Diphosphate Galactose
pubmed:year
2004
pubmed:articleTitle
Effect of the Met344His mutation on the conformational dynamics of bovine beta-1,4-galactosyltransferase: crystal structure of the Met344His mutant in complex with chitobiose.
pubmed:affiliation
Structural Glycobiology Section, Laboratory of Experimental and Computational Biology, SAIC-Frederick, Inc., Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702-1201, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.