InterPro : IPR005738

Name  DNA topoisomerase III Short Name  TopoIII
Type  Family Description  DNA topoisomerases regulate the number of topological links between two DNA strands (i.e. change the number of superhelical turns) by catalysing transient single- or double-strand breaks, crossing the strands through one another, then resealing the breaks []. These enzymes have several functions: to remove DNA supercoils during transcription and DNA replication; for strand breakage during recombination; for chromosome condensation; and to disentangle intertwined DNA during mitosis [, ]. DNA topoisomerases are divided into two classes: type I enzymes(; topoisomerases I, III and V) break single-strand DNA, and type II enzymes (; topoisomerases II, IV and VI) break double-strand DNA [].Type I topoisomerases are ATP-independent enzymes (except for reverse gyrase), and can be subdivided according to their structure and reaction mechanisms: type IA (bacterial and archaeal topoisomerase I, topoisomerase III and reverse gyrase) and type IB (eukaryotic topoisomerase I and topoisomerase V). These enzymes are primarily responsible for relaxing positively and/or negatively supercoiled DNA, except for reverse gyrase, which can introduce positive supercoils into DNA. This entry describes topoisomerase III from bacteria. In Escherichia coli, topoisomerase III functions as the principal cellular decatenase, capable of unlinking replicating daughter chromosomes []. Topoisomerase III requires single-stranded DNA for binding, so it is more efficient at decatenating chromosomes if the DNA circles contain a small gap. It appears that Topoisomerase III works by removing precatenanes, an alternative form that can be taken by the positive linkages that arise between the daughter chromosomes during replication. Topoisomerase III shows considerable identity to bacterial topoisomerase I, except that it lacks the zinc finger region found in the latter.

Sequence Features

GO Displayer


InterPro protein domain ID --> Contigs



0 Child Features

4 Contains

Id Name Short Name Type
IPR013497 DNA topoisomerase, type IA, central Topo_IA_cen Domain
IPR003602 DNA topoisomerase, type IA, DNA-binding domain Topo_IA_DNA-bd_dom Domain
IPR003601 DNA topoisomerase, type IA, domain 2 Topo_IA_2 Domain
IPR013824 DNA topoisomerase, type IA, central region, subdomain 1 Topo_IA_cen_sub1 Domain

0 Found In

1 Parent Features

Id Name Short Name Type
IPR000380 DNA topoisomerase, type IA Topo_IA Family

5 Publications

First Author Title Year Journal Volume Pages
Roca J The mechanisms of DNA topoisomerases. 1995 Trends Biochem Sci 20 156-60
Champoux JJ DNA topoisomerases: structure, function, and mechanism. 2001 Annu Rev Biochem 70 369-413
Gadelle D Phylogenomics of type II DNA topoisomerases. 2003 Bioessays 25 232-42
Wang JC Cellular roles of DNA topoisomerases: a molecular perspective. 2002 Nat Rev Mol Cell Biol 3 430-40
Nurse P Topoisomerase III can serve as the cellular decatenase in Escherichia coli. 2003 J Biol Chem 278 8653-60

To cite PlanMine, please refer to the following publication:

Rozanski, A., Moon, H., Brandl, H., Martín-Durán, J. M., Grohme, M., Hüttner, K., Bartscherer, K., Henry, I., & Rink, J. C.
PlanMine 3.0—improvements to a mineable resource of flatworm biology and biodiversity
Nucleic Acids Research, gky1070. doi:10.1093/nar/gky1070 (2018)