Domain Annotation: SCOP/SCOPe Classification SCOP-e Database Homepage

ChainsDomain InfoClassFoldSuperfamilyFamilyDomainSpeciesProvenance Source (Version)
Ad1d6ma_ Multi-domain proteins (alpha and beta) Prokaryotic type I DNA topoisomerase Prokaryotic type I DNA topoisomerase Prokaryotic type I DNA topoisomerase DNA topoisomerase III (Escherichia coli ) [TaxId: 562 ], SCOPe (2.08)

Domain Annotation: SCOP2 Classification SCOP2 Database Homepage

ChainsTypeFamily Name Domain Identifier Family IdentifierProvenance Source (Version)
ASCOP2B SuperfamilyProkaryotic type I DNA topoisomerase clamp domain-like 8033735 3001789 SCOP2B (2022-06-29)
ASCOP2B SuperfamilyToprim domain-like 8055739 3000737 SCOP2B (2022-06-29)

Domain Annotation: ECOD Classification ECOD Database Homepage

ChainsFamily NameDomain Identifier ArchitecturePossible HomologyHomologyTopologyFamilyProvenance Source (Version)
ATopoisom_bac_2nde1d6mA1 A: beta barrelsX: LigT-likeH: Prokaryotic type I DNA topoisomerase beta-barrel domain (From Topology)T: Prokaryotic type I DNA topoisomerase beta-barrel domainF: Topoisom_bac_2ndECOD (1.6)
ATopoisom_bac_3rde1d6mA2 A: alpha arraysX: HTHH: HTHT: wingedF: Topoisom_bac_3rdECOD (1.6)
ATopoisom_bac_1st_1e1d6mA3 A: alpha arraysX: HTHH: HTHT: wingedF: Topoisom_bac_1st_1ECOD (1.6)
AToprime1d6mA4 A: a/b three-layered sandwichesX: HAD domain-likeH: HAD domain-relatedT: Toprim domainF: ToprimECOD (1.6)

Domain Annotation: CATH CATH Database Homepage

ChainDomainClassArchitectureTopologyHomologyProvenance Source (Version)
A3.40.50.140 Alpha Beta 3-Layer(aba) Sandwich Rossmann fold CATH (4.3.0)
A1.10.460.10 Mainly Alpha Orthogonal Bundle Topoisomerase I domain 2CATH (4.3.0)
A2.70.20.10 Mainly Beta Distorted Sandwich Topoisomerase I domain 3CATH (4.3.0)
A1.10.290.10 Mainly Alpha Orthogonal Bundle Topoisomerase I domain 4CATH (4.3.0)

Protein Family Annotation Pfam Database Homepage

ChainsAccessionNameDescriptionCommentsSource
PF01131DNA topoisomerase (Topoisom_bac)DNA topoisomerase- Family
PF01751Toprim domain (Toprim)Toprim domain- Family

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

ChainsPolymerMolecular FunctionBiological ProcessCellular Component
DNA TOPOISOMERASE III

Structure Motif Annotation: Mechanism and Catalytic Site Atlas M-CSA Database Homepage

ChainsEnzyme NameDescriptionCatalytic Residues
DNA topoisomerase (type III)  M-CSA #64

Topoisomerases catalyse the winding and unwinding of super-coiled DNA, a process vital during DNA replication, transcription and repair. Type I topoisomerases reversibly cut one strand of the DNA helix, and can only relax supercoils. Analysis of sequence and mutagenesis data indicates that the type Ia topoisomerases (those found in prokaryotes, and the example given here) may be related to the major family of type II topoisomerases (found in all life apart from some archaea). Type II topoisomerases cut both strands and can either relax or tighten super-coils, but require ATP hydrolysis for catalytic turnover. All topoisomerases recorded form an intermediate with a tyr-DNA covalent bond during catalysis.

Defined by 6 residues: GLU:A-7LYS:A-8ASP:A-103ASP:A-105TYR:A-328ARG:A-330
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