Linked Life Data

12752432

Source:http://linkedlifedata.com/resource/pubmed/id/12752432

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
2003-5-19
pubmed:databankReference
pubmed:abstractText
Glycogen phosphorylases (GPs) constitute a family of widely spread catabolic alpha1,4-glucosyltransferases that are active as dimers of two identical, pyridoxal 5'-phosphate-containing subunits. In GP from Corynebacterium callunae, physiological concentrations of phosphate are required to inhibit dissociation of protomers and cause a 100-fold increase in kinetic stability of the functional quarternary structure. To examine interactions involved in this large stabilization, we have cloned and sequenced the coding gene and have expressed fully active C. callunae GP in Escherichia coli. By comparing multiple sequence alignment to structure-function assignments for regulated and nonregulated GPs that are stable in the absence of phosphate, we have scrutinized the primary structure of C. callunae enzyme for sequence changes possibly related to phosphate-dependent dimer stability. Location of Arg234, Arg236, and Arg242 within the predicted subunit-to-subunit contact region made these residues primary candidates for site-directed mutagenesis. Individual Arg-->Ala mutants were purified and characterized using time-dependent denaturation assays in urea and at 45 degrees C. R234A and R242A are enzymatically active dimers and in the absence of added phosphate, they display a sixfold and fourfold greater kinetic stability of quarternary interactions than the wild-type, respectively. The stabilization by 10 mm of phosphate was, however, up to 20-fold greater in the wild-type than in the two mutants. The replacement of Arg236 by Ala was functionally silent under all conditions tested. Arg234 and Arg242 thus partially destabilize the C. callunae GP dimer structure, and phosphate binding causes a change of their tertiary or quartenary contacts, likely by an allosteric mechanism, which contributes to a reduced protomer dissociation rate.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:volume
270
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2126-36
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed-meshheading:12752432-Allosteric Site, pubmed-meshheading:12752432-Amino Acid Sequence, pubmed-meshheading:12752432-Arginine, pubmed-meshheading:12752432-Binding Sites, pubmed-meshheading:12752432-Blotting, Southern, pubmed-meshheading:12752432-Circular Dichroism, pubmed-meshheading:12752432-Cloning, Molecular, pubmed-meshheading:12752432-Corynebacterium, pubmed-meshheading:12752432-DNA, pubmed-meshheading:12752432-Dimerization, pubmed-meshheading:12752432-Escherichia coli, pubmed-meshheading:12752432-Gene Library, pubmed-meshheading:12752432-Glucans, pubmed-meshheading:12752432-Hydrogen-Ion Concentration, pubmed-meshheading:12752432-Kinetics, pubmed-meshheading:12752432-Molecular Sequence Data, pubmed-meshheading:12752432-Mutagenesis, Site-Directed, pubmed-meshheading:12752432-Oligonucleotides, pubmed-meshheading:12752432-Plasmids, pubmed-meshheading:12752432-Protein Structure, Quaternary, pubmed-meshheading:12752432-Protein Structure, Tertiary, pubmed-meshheading:12752432-Recombinant Proteins, pubmed-meshheading:12752432-Sequence Homology, Amino Acid, pubmed-meshheading:12752432-Starch Phosphorylase, pubmed-meshheading:12752432-Temperature
pubmed:year
2003
pubmed:articleTitle
Tracking interactions that stabilize the dimer structure of starch phosphorylase from Corynebacterium callunae. Roles of Arg234 and Arg242 revealed by sequence analysis and site-directed mutagenesis.
pubmed:affiliation
Institute of Food Technology, University of Agricultural Sciences, Vienna, Austria.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't