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 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 organelle organization 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 U.S. National Science Foundation (DBI-2321666), 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 R01GM157729.