Linked Life Data

1322412

Source:http://linkedlifedata.com/resource/pubmed/id/1322412

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
22
pubmed:dateCreated
1992-8-28
pubmed:abstractText
Analysis of vaccinia topoisomerase mutants that are impaired in DNA relaxation has allowed the identification of amino acid residues required for the transesterification step of catalysis. Missense mutations of wild-type residues Gly-132----Asp and Arg-223----Gln rendered the protein inert in formation of the covalent enzyme-DNA complex and hence completely inactive in DNA relaxation. Mutations of Thr-147----Ile and Gly-132----Ser caused severe defects in covalent adduct formation that correlated with the extent of inhibition of relaxation. None of these point mutations had an effect on noncovalent DNA binding sufficient to account for the defect in relaxation. Deletion of amino- or carboxyl-terminal portions of the polypeptide abrogated noncovalent DNA binding. Two distinct topoisomerase-DNA complexes were resolved by native gel electrophoresis. One complex, which was unique to those proteins competent in covalent adduct formation, contained topoisomerase bound to the 5'-portion of the incised DNA strand. The 3'-segment of the cleaved strand had dissociated spontaneously. This complex was isolated and shown to catalyze transfer of the covalently bound DNA to a heterologous acceptor oligonucleotide, thereby proving that the covalent adduct between protein and duplex DNA is a true intermediate in strand breakage and reunion. The role of the active site region of eukaryotic topoisomerase in determining sensitivity or resistance to camptothecin was examined by converting the active site region of the resistant vaccinia enzyme (SKRAY274) to that of the drug-sensitive yeast enzyme (SKINY). The SKINY mutation did not alter the resistance of the vaccinia enzyme to the cleavage-enhancing effects of camptothecin.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
267
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
15984-92
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Covalent and noncovalent DNA binding by mutants of vaccinia DNA topoisomerase I.
pubmed:affiliation
Program in Molecular Biology, Sloan-Kettering Institute, New York, New York.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't