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1a35
From Proteopedia
HUMAN TOPOISOMERASE I/DNA COMPLEX
Overview
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.
About this Structure
1A35 is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Crystal structures of human topoisomerase I in covalent and noncovalent complexes with DNA., Redinbo MR, Stewart L, Kuhn P, Champoux JJ, Hol WG, Science. 1998 Mar 6;279(5356):1504-13. PMID:9488644 Page seeded by OCA on Fri May 2 09:44:25 2008
