Linked Life Data

14556639

Source:http://linkedlifedata.com/resource/pubmed/id/14556639

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
41
pubmed:dateCreated
2003-10-14
pubmed:abstractText
Human polynucleotide kinase (hPNK), which possesses both 5'-DNA kinase and 3'-DNA phosphatase activities, is a DNA repair enzyme required for processing and rejoining of single- and double-strand-break termini. Full-length hPNK was subjected to sedimentation and spectroscopic analyses in association with its ligands, a 20-mer oligonucleotide, ATP, and AMP-PNP (a nonhydrolyzable analogue of ATP). Sedimentation equilibrium measurements indicated that hPNK was a monomer in the presence and absence of the ligands. Circular dichroism measurements revealed that the ligands induced different conformational changes in hPNK, although AMP-PNP induced the same conformational changes as ATP. CD also indicated that the oligonucleotide could bind to the protein-AMP-PNP complex. Protein-ligand binding affinities and stoichiometries were determined by measuring changes in protein intrinsic fluorescence. Titrating hPNK with the oligonucleotide indicated tight binding with a K(d) value of 1.3 microM and with 1:1 stoichiometry. A 5'-phosphorylated oligonucleotide with the same sequence exhibited an almost 6-fold lower affinity (K(d) value, 7.2 microM). ATP and AMP-PNP bound with high affinity (K(d) values, respectively, of 1.4 and 1.6 microM), and the observed binding stoichiometries were 1:1. Furthermore, the nonphosphorylated oligonucleotide was able to bind to hPNK in the presence of AMP-PNP with a K(d) value of 2.5 microM, confirming the formation of a ternary complex. This study provides the first direct physical evidence for such a ternary complex involving a polynucleotide kinase, AMP-PNP, and an oligonucleotide, and supports a reaction mechanism in which ATP and DNA bind simultaneously to the enzyme.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
42
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12077-84
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Spectroscopic studies of DNA and ATP binding to human polynucleotide kinase: evidence for a ternary complex.
pubmed:affiliation
Department of Experimental Oncology, Cross Cancer Institute, and Department of Oncology, University of Alberta, Edmonton, Alberta T6G 1Z2, Canada. rajam.mani@cancerboard.ab.ca
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't