Linked Life Data

17511471

Source:http://linkedlifedata.com/resource/pubmed/id/17511471

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
23
pubmed:dateCreated
2007-6-5
pubmed:abstractText
The flavoenzyme UDP-galactopyranose mutase (UGM) is a mediator of cell wall biosynthesis in many pathogenic microorganisms. UGM catalyzes a unique ring contraction reaction that results in the conversion of UDP-galactopyranose (UDP-Galp) to UDP-galactofuranose (UDP-Galf). UDP-Galf is an essential precursor to the galactofuranose residues found in many different cell wall glycoconjugates. Due to the important consequences of UGM catalysis, structural and biochemical studies are needed to elucidate the mechanism and identify the key residues involved. Here, we report the results of site-directed mutagenesis studies on the absolutely conserved residues in the putative active site cleft. By generating variants of the UGM from Klebsiella pneumoniae, we have identified two arginine residues that play critical catalytic roles (alanine substitution abolishes detectable activity). These residues also have a profound effect on the binding of a fluorescent UDP derivative that inhibits UGM, suggesting that the Arg variants are defective in their ability to bind substrate. One of the residues, Arg280, is located in the putative active site, but, surprisingly, the structural studies conducted to date suggest that Arg174 is not. Molecular dynamics simulations indicate that closed UGM conformations can be accessed in which this residue contacts the pyrophosphoryl group of the UDP-Gal substrates. These results provide strong evidence that the mobile loop, noted in all the reported crystal structures, must move in order for UGM to bind its UDP-galactose substrate.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
46
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6723-32
pubmed:dateRevised
2007-12-3
pubmed:meshHeading
pubmed-meshheading:17511471-Amino Acid Sequence, pubmed-meshheading:17511471-Amino Acid Substitution, pubmed-meshheading:17511471-Arginine, pubmed-meshheading:17511471-Bacterial Proteins, pubmed-meshheading:17511471-Binding Sites, pubmed-meshheading:17511471-Cloning, Molecular, pubmed-meshheading:17511471-Conserved Sequence, pubmed-meshheading:17511471-DNA Primers, pubmed-meshheading:17511471-Escherichia coli, pubmed-meshheading:17511471-Intramolecular Transferases, pubmed-meshheading:17511471-Kinetics, pubmed-meshheading:17511471-Klebsiella pneumoniae, pubmed-meshheading:17511471-Models, Molecular, pubmed-meshheading:17511471-Molecular Sequence Data, pubmed-meshheading:17511471-Mutagenesis, Site-Directed, pubmed-meshheading:17511471-Mycobacterium tuberculosis, pubmed-meshheading:17511471-Protein Conformation, pubmed-meshheading:17511471-Recombinant Proteins, pubmed-meshheading:17511471-Thermodynamics, pubmed-meshheading:17511471-Uridine Diphosphate Galactose
pubmed:year
2007
pubmed:articleTitle
Site-directed mutagenesis of UDP-galactopyranose mutase reveals a critical role for the active-site, conserved arginine residues.
pubmed:affiliation
Department of Chemistry, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5C9.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural