InterPro : IPR000380

Name  DNA topoisomerase, type IA Short Name  Topo_IA
Type  Family Description  This entry describes the type IA topoisomerases, which are highly conserved enzymes that are structurally distinct from type IB enzymes. The structures of both topoisomerases I and III have been elucidated, and consist of four domains that together form a toroidal molecule with a central hole that is large enough to accommodate single- and double-stranded DNA []. It is believed that the domains transiently separate from one another to allow the entrance and exit of DNA strands.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.

Sequence Features

GO Displayer


InterPro protein domain ID --> Contigs



3 Child Features

Id Name Short Name Type
IPR028612 DNA topoisomerase I, type IA Topoisom_1_IA Family
IPR005736 Reverse gyrase Reverse_gyrase Family
IPR005738 DNA topoisomerase III TopoIII Family

7 Contains

Id Name Short Name Type
IPR006171 Toprim domain Toprim_domain Domain
IPR013497 DNA topoisomerase, type IA, central Topo_IA_cen Domain
IPR013826 DNA topoisomerase, type IA, central region, subdomain 3 Topo_IA_cen_sub3 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
IPR013825 DNA topoisomerase, type IA, central region, subdomain 2 Topo_IA_cen_sub2 Domain

0 Found In

0 Parent Features

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
Li Z The mechanism of type IA topoisomerase-mediated DNA topological transformations. 2001 Mol Cell 7 301-7

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)