Linked Life Data

14506224

Source:http://linkedlifedata.com/resource/pubmed/id/14506224

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
49
pubmed:dateCreated
2003-12-3
pubmed:abstractText
The roles of ATP binding and hydrolysis by MutS in mismatch repair are poorly understood. MutS E694A, in which Glu-694 of the Walker B motif is substituted with alanine, is defective in hydrolysis of bound ATP and has been reported to support MutL-dependent activation of the MutH d(GATC) endonuclease in a trans DNA activation assay (Junop, M. S., Obmolova, G., Rausch, K., Hsieh, P., and Yang, W. (2001) Mol. Cell 7, 1-12). Because the MutH trans activation assay used in these previous studies was characterized by high background and low efficiency, we have re-evaluated the activities of MutS E694A. In contrast to native MutS, which can be isolated in a nucleotide-free form, purified MutS E694A contains 1.0 mol of bound ATP per dimer equivalent, and substoichiometric levels of bound ADP (0.08-0.58 mol/dimer), consistent with the suggestion that the ADP.MutS.ATP complex comprises a significant fraction of the protein in solution (Bjornson, K. P. and Modrich, P. (2003) J. Biol. Chem. 278, 18557-18562). In the presence of Mg2+, endogenous ATP is hydrolyzed with a rate constant of 0.12 min-1 at 30 degrees C, and hydrolysis yields a protein that displays increased specificity for heteroduplex DNA. As observed with wild type MutS, ATP can promote release of MutS E694A from a mismatch. However, the mutant protein is defective in the methyl-directed, mismatch- and MutL-dependent cis activation of MutH endonuclease on a 6.4-kilobase pair heteroduplex, displaying only 1 to 2% of the activity of wild type MutS. The mutant protein also fails to support normal assembly of the MutS.MutL.DNA ternary complex. Although a putative ternary complex can be observed in the presence of MutS E694A, assembly of this structure displays little if any dependence on a mismatched base pair.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
278
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
49505-11
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Hydrolytically deficient MutS E694A is defective in the MutL-dependent activation of MutH and in the mismatch-dependent assembly of the MutS.MutL.heteroduplex complex.
pubmed:affiliation
Howard Hughes Medical Institute and Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.