1MW9: Crystal Structure Of H365r Mutant Of 67 Kda N-terminal Fragment Of E. Coli Dna Topoisomerase I

Citation:
Abstract
In order to gain insights into the mechaism of ssDNA binding and recognition by Escherichia coli DNA topoisomerase I, the structure of the 67 kDa N-terminal fragment of topoisomerase I was solved in complex with ssDNA. The structure reveals a new conformational stage in the multistep catalytic cycle of type IA topoisomerases. In the structure, the ssDNA binding groove leading to the active site is occupied, but the active site is not fully formed. Large conformational changes are not seen; instead, a single helix parallel to the ssDNA binding groove shifts to clamp the ssDNA. The structure helps clarify the temporal sequence of conformational events, starting from an initial empty enzyme and proceeding to a ssDNA-occupied and catalytically competent active site.
PDB ID: 1MW9Download
MMDB ID: 24936
PDB Deposition Date: 2002/9/27
Updated in MMDB: 2003/12
Experimental Method:
x-ray diffraction
Resolution: 1.67  Å
Source Organism:
Similar Structures:
Biological Unit for 1MW9: monomeric; determined by author
Molecular Components in 1MW9
Label Count Molecule
Protein (1 molecule)
1
DNA Topoisomerase I(Gene symbol: topA)
Molecule annotation
Chemicals (9 molecules)
1
9
* Click molecule labels to explore molecular sequence information.

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