Overview for MACiE Entry M0064
EC Number: 22.214.171.124 (A member of the Isomerases, Other isomerases, Sole sub-subclass for isomerases that do not belong in the other subclasses)
Enzyme Name: DNA topoisomerase (type IA)
Biological Species: Escherichia coli (Bacteria)
Catalytic Chain UniprotKB Accession Codes:
Representative PDB Code: 1d6m - CRYSTAL STRUCTURE OF E. COLI DNA TOPOISOMERASE III (Resolution = 3.00 Å).
Display structure information
Overall Comment: Although Mg(II) is required for the relaxation of the supercoiled DNA, its role in catalysis is not yet determined .
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Stepwise Description of the Reaction
|Step 1||Tyr328 acts as a nucleophilic, attacking the phosphorous of the DNA molecule, which proceeds through a pentavalent transition state, before eliminating the 5' DNA, with concomitant deprotonation of Glu7.|
|Step 2||The DNA uncoils before Glu7 deprotonates the 5'-OH, which initiates a nucleophilic attack upon the phosphorous atom, which proceeds through a pentavalent transition state, before eliminating Tyr328.|
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Catalytic Residues Involved
||Location of Function
- A. Changela et al. (2001), Nature, 411, 1077-1081. Crystal structure of a complex of a type IA DNA topoisomerase with a single-stranded DNA molecule.
- J. J. Champoux (2002), Trends Pharmacol. Sci., 23, 199-201. A first view of the structure of a type IA topoisomerase with bound DNA.
Homologue information for M0064 (1d6m)
MACiE Homologues (within the PDB)
MACiE Homologues (within UniprotKB/SwissProt)
Entries with the same EC number (different mechanisms):
||DNA topoisomerase (type IB)
Compare of the other reactions in MACiE with EC number 126.96.36.199
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