Linked Life Data

11290737

Source:http://linkedlifedata.com/resource/pubmed/id/11290737

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
26
pubmed:dateCreated
2001-6-25
pubmed:abstractText
We have studied the processing of O(6)-methylguanine (m6G)-containing oligonucleotides and N-methyl-N-nitrosourea (MNU)-treated DNA templates by the 3' --> 5' exonuclease of T4 DNA polymerase. In vitro biochemical analyses demonstrate that the exonuclease can remove bases opposite a defined m6G lesion. The efficiency of excision of a terminal m6G.T was similar to that of m6G.C, and both were excised as efficiently as a G.T substrate. Partitioning assays between the polymerase and exonuclease activities, performed in the presence of dNTPs, resulted in repeated incorporation and excision events opposite the m6G lesion. This idling produces dramatically less full-length product, relative to natural substrates, indicating that the 3' --> 5' exonuclease may contribute to DNA synthesis inhibition by alkylating agents. Genetic data obtained using an in vitro herpes simplex virus-thymidine kinase assay support the inefficiency of the exonuclease as a "proofreading" activity for m6G, since virtually all mutations produced by the native enzyme using MNU-treated templates were G --> A transitions. Comparison of MNU dose-response curves for exonuclease-proficient and -deficient forms of T4 polymerase reveals that the exonuclease efficiently removes 50-86% of total premutagenic alkyl mispairs. We propose that idling of exonuclease-proficient polymerases at m6G lesions during repair DNA synthesis provides the biochemical explanation for cellular cytotoxicity of methylating agents.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
29
pubmed:volume
276
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
24286-92
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
The 3' --> 5' exonuclease of T4 DNA polymerase removes premutagenic alkyl mispairs and contributes to futile cycling at O6-methylguanine lesions.
pubmed:affiliation
Gittlen Cancer Research Institute, Department of Pathology and the Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, 500 University Dr., Hershey, Pennsylvania 17033, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't