Crystal structures of human topoisomerase I in covalent and noncovalent complexes with DNA.
Redinbo, M.R., Stewart, L., Kuhn, P., Champoux, J.J., Hol, W.G.(1998) Science 279: 1504-1513
- PubMed: 9488644 
- DOI: 10.1126/science.279.5356.1504
- Primary Citation of Related Structures:  
1A31, 1A35 - PubMed 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 ...