Linked Life Data

10551862

Source:http://linkedlifedata.com/resource/pubmed/id/10551862

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
46
pubmed:dateCreated
2000-1-3
pubmed:abstractText
Human topoisomerase I is composed of four major domains: the highly charged NH(2)-terminal region, the conserved core domain, the positively charged linker domain, and the highly conserved COOH-terminal domain. Near complete enzyme activity can be reconstituted by combining recombinant polypeptides that approximate the core and COOH-terminal domains, although DNA binding is reduced somewhat for the reconstituted enzyme (Stewart, L., Ireton, G. C., and Champoux, J. J. (1997) J. Mol. Biol. 269, 355-372). A reconstituted enzyme comprising the core domain plus a COOH-terminal fragment containing the complete linker region exhibits the same biochemical properties as a reconstituted enzyme lacking the linker altogether, and thus detachment of the linker from the core domain renders the linker non-functional. The rate of religation by the reconstituted enzyme is increased relative to the forms of the enzyme containing the linker indicating that in the intact enzyme the linker slows religation. Relaxation of plasmid DNA by full-length human topoisomerase I or a 70-kDa form of the enzyme that is missing only the non-essential NH(2)-terminal domain (topo70) is inhibited approximately 16-fold by the anticancer compound, camptothecin, whereas the reconstituted enzyme is nearly resistant to the inhibitory effects of the drug despite similar affinities for the drug by the two forms of the enzyme. Based on these results and in light of the crystal structure of human topoisomerase I, we propose that the linker plays a role in hindering supercoil relaxation during the normal relaxation reaction and that camptothecin inhibition of DNA relaxation depends on a direct effect of the drug on DNA rotation that is also dependent on the linker.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
274
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
32950-60
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
A functional linker in human topoisomerase I is required for maximum sensitivity to camptothecin in a DNA relaxation assay.
pubmed:affiliation
Department of Microbiology, School of Medicine, University of Washington, Seattle, Washington 98195-7242, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't