Linked Life Data

19341290

Source:http://linkedlifedata.com/resource/pubmed/id/19341290

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
20
pubmed:dateCreated
2009-5-19
pubmed:abstractText
Human DNA is continuously damaged by exogenous and endogenous genotoxic insults. To counteract DNA damage and ensure the completion of DNA replication, cells possess specialized DNA polymerases (Pols) that bypass a variety of DNA lesions. Human DNA polymerase kappa (hPolkappa) is a member of the Y-family of DNA Pols and a direct counterpart of DinB in Escherichia coli. hPolkappa is characterized by its ability to bypass several DNA adducts [e.g., benzo[a]pyrene diolepoxide-N(2)-deoxyguanine (BPDE-N(2)-dG) and thymine glycol] and efficiently extend primers with mismatches at the termini. hPolkappa is structurally distinct from E. coli DinB in that it possesses an approximately 100-amino acid extension at the N-terminus. Here, we report that tyrosine 112 (Y112), the steric gate amino acid of hPolkappa, which distinguishes dNTPs from rNTPs by sensing the 2'-hydroxy group of incoming nucleotides, plays a crucial role in extension reactions with mismatched primer termini. When Y112 was replaced with alanine, the amino acid change severely reduced the catalytic constant, i.e., k(cat), of the extending mismatched primers and lowered the efficiency, i.e., k(cat)/K(m), of this process by approximately 400-fold compared with that of the wild-type enzyme. In contrast, the amino acid replacement did not reduce the insertion efficiency of dCMP opposite BPDE-N(2)-dG in template DNA, nor did it affect the ability of hPolkappa to bind strongly to template-primer DNA with BPDE-N(2)-dG/dCMP. We conclude that the steric gate of hPolkappa is a major fidelity factor that regulates extension reactions from mismatched primer termini.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
1520-4995
pubmed:author
pubmed:issnType
Electronic
pubmed:day
26
pubmed:volume
48
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4239-46
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
The steric gate amino acid tyrosine 112 is required for efficient mismatched-primer extension by human DNA polymerase kappa.
pubmed:affiliation
Division of Genetics and Mutagenesis, National Institute of Health Sciences, Setagaya-ku, Tokyo 158-8501, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural