Annotations: 3IGC

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
A	Topoisom_I_C	e3igcA2	A: alpha arrays	X: HTH	H: HTH	T: DNA breaking-rejoining enzymes	F: Topoisom_I_C	ECOD (1.6)
A	Topoisom_I_N	e3igcA1	A: alpha arrays	X: HTH	H: HTH	T: DNA breaking-rejoining enzymes	F: Topoisom_I_N	ECOD (1.6)
A	VirDNA-topo-I_N	e3igcA3	A: a+b two layers	X: DNA topoisomerase I domain (From Topology)	H: DNA topoisomerase I domain (From Topology)	T: DNA topoisomerase I domain	F: VirDNA-topo-I_N	ECOD (1.6)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
A	3.30.66.10	Alpha Beta	2-Layer Sandwich	Viral Topoisomerase I	DNA topoisomerase I domain	CATH (4.3.0)
A	3.90.15.10	Alpha Beta	Alpha-Beta Complex	Topoisomerase I	Chain A, domain 3	CATH (4.3.0)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A	PF09266	Viral DNA topoisomerase I, N-terminal (VirDNA-topo-I_N)	Viral DNA topoisomerase I, N-terminal	Members of this family are predominantly found in viral DNA topoisomerase, and assume a beta(2)-alpha-beta-alpha-beta(2) fold, with a left-handed crossover between strands beta2 and beta3 [1].	Domain
A	PF01028	Eukaryotic DNA topoisomerase I, catalytic core (Topoisom_I)	Eukaryotic DNA topoisomerase I, catalytic core	Topoisomerase I promotes the relaxation of DNA superhelical tension by introducing a transient single-stranded break in duplex DNA and are vital for the processes of replication, transcription, and recombination [2].	Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
A	DNA topoisomerase 1	DNA binding binding organic cyclic compound binding nucleic acid binding isomerase activity DNA topoisomerase type I (single strand cut, ATP-independent) activity catalytic activity, acting on DNA DNA topoisomerase activity catalytic activity, acting on a nucleic acid catalytic activity	chromosome organization primary metabolic process DNA conformation change DNA metabolic process nucleic acid metabolic process cellular component organization nucleobase-containing compound metabolic process DNA topological change organic cyclic compound metabolic process organelle organization organic substance metabolic process cellular process metabolic process cellular component organization or biogenesis chromosome organization primary metabolic process DNA conformation change DNA metabolic process nucleic acid metabolic process cellular component organization nucleobase-containing compound metabolic process DNA topological change organic cyclic compound metabolic process organelle organization organic substance metabolic process cellular process metabolic process cellular component organization or biogenesis macromolecule metabolic process	virion component
B	5'-D(GPTPGPTPCPGPCPCPCPTP*T)-3'	-	-	-
C	5'-D(APTPTPCP*C)-3'	-	-	-
D	5'-D(CPGPGPAPAPTPAPAPGPGPGPCPGPAPCPA)-3'	-	-	-

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A	IPR035447	DNA topoisomerase I, N-terminal domain superfamily	Homologous Superfamily
A	IPR011010	DNA breaking-rejoining enzyme, catalytic core	Homologous Superfamily
A	IPR001631	DNA topoisomerase I	Family
A	IPR013500	DNA topoisomerase I, catalytic core, eukaryotic-type	Domain
A	IPR014711	DNA topoisomerase I, catalytic core, alpha-helical subdomain, eukaryotic-type	Homologous Superfamily
A	IPR018521	DNA topoisomerase I, active site	Active Site
A	IPR015346	DNA topoisomerase I, N-terminal, viral	Domain

RCSB PDB Core Operations are funded by the National Science Foundation (DBI-1832184), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM133198.