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  • Crystal structures of human topoisomerase I in covalent and noncovalent complexes with DNA.

Crystal structures of human topoisomerase I in covalent and noncovalent complexes with DNA.

Science (New York, N.Y.) (1998-03-21)
M R Redinbo, L Stewart, P Kuhn, J J Champoux, W G Hol
ABSTRACT

Topoisomerases I promote the relaxation of DNA superhelical tension by introducing a transient single-stranded break in duplex DNA and are vital for the processes of replication, transcription, and recombination. The crystal structures at 2.1 and 2.5 angstrom resolution of reconstituted human topoisomerase I comprising the core and carboxyl-terminal domains in covalent and noncovalent complexes with 22-base pair DNA duplexes reveal an enzyme that "clamps" around essentially B-form DNA. The core domain and the first eight residues of the carboxyl-terminal domain of the enzyme, including the active-site nucleophile tyrosine-723, share significant structural similarity with the bacteriophage family of DNA integrases. A binding mode for the anticancer drug camptothecin is proposed on the basis of chemical and biochemical information combined with these three-dimensional structures of topoisomerase I-DNA complexes.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Topo I (C651-765) (C terminal domain) human, recombinant, expressed in insect cells, ≥80% (SDS-PAGE)
Sigma-Aldrich
Topo I (197-651) (core domain) human, recombinant, expressed in insect cells, ≥80% (SDS-PAGE)