Annotations: 2B9S

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
D [auth A]	Topoisom_I_N_C	e2b9sA1	A: beta complex topology	X: Beta-strand domain in eukaryotic DNA topoisomerase I, N-terminal DNA-binding fragment (From Topology)	H: Beta-strand domain in eukaryotic DNA topoisomerase I, N-terminal DNA-binding fragment (From Topology)	T: Beta-strand domain in eukaryotic DNA topoisomerase I, N-terminal DNA-binding fragment	F: Topoisom_I_N_C	ECOD (1.6)
D [auth A]	Topoisom_I_N	e2b9sA3	A: alpha arrays	X: HTH	H: HTH	T: DNA breaking-rejoining enzymes	F: Topoisom_I_N	ECOD (1.6)
D [auth A]	Topoisom_I_N_N	e2b9sA2	A: alpha arrays	X: Alpha-helical domain in eukaryotic DNA topoisomerase I, N-terminal DNA-binding fragment (From Topology)	H: Alpha-helical domain in eukaryotic DNA topoisomerase I, N-terminal DNA-binding fragment (From Topology)	T: Alpha-helical domain in eukaryotic DNA topoisomerase I, N-terminal DNA-binding fragment	F: Topoisom_I_N_N	ECOD (1.6)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
D [auth A]	2.170.11.10	Mainly Beta	Beta Complex	DNA Topoisomerase I	domain 2	CATH (4.3.0)
D [auth A]	1.10.10.41	Mainly Alpha	Orthogonal Bundle	Arc Repressor Mutant, subunit A	Yeast DNA topoisomerase - domain 1	CATH (4.3.0)
D [auth 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
D [auth A]	PF02919	Eukaryotic DNA topoisomerase I, DNA binding fragment (Topoisom_I_N)	Eukaryotic DNA topoisomerase I, DNA binding fragment	-	Family
D [auth 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 [auth C]	5'-D(APAPAPAPAPGPAPCPTPT)-3'	-	-	-
B [auth D]	5'-D(APGPAPAPAPAPAPTPTPTPTPT)-3'	-	-	-
C [auth E]	5'-D(APAPAPAPAPTPTPTPTPTPCPTPAPAPGPTPCPTPTPTPTPT)-3'	-	-	-
D [auth A]	topoisomerase I-like protein	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	nucleobase-containing compound metabolic process DNA replication metabolic process cellular process primary metabolic process DNA metabolic process macromolecule metabolic process nucleic acid metabolic process cell cycle chromosome segregation cell cycle process chromosome organization DNA conformation change cellular component organization nucleobase-containing compound metabolic process DNA replication metabolic process cellular process primary metabolic process DNA metabolic process macromolecule metabolic process nucleic acid metabolic process cell cycle chromosome segregation cell cycle process chromosome organization DNA conformation change cellular component organization DNA topological change organelle organization cellular component organization or biogenesis	membrane-bounded organelle intracellular anatomical structure nucleus membrane-enclosed lumen intracellular membraneless organelle intracellular membrane-bounded organelle nucleolus intracellular organelle lumen intracellular organelle cellular anatomical structure organelle lumen organelle membraneless organelle nuclear lumen membrane-bounded organelle intracellular anatomical structure nucleus membrane-enclosed lumen intracellular membraneless organelle intracellular membrane-bounded organelle nucleolus intracellular organelle lumen intracellular organelle cellular anatomical structure organelle lumen organelle membraneless organelle nuclear lumen chromosome
E [auth B]	DNA topoisomerase I-like protein	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	nucleobase-containing compound metabolic process DNA replication metabolic process cellular process primary metabolic process DNA metabolic process macromolecule metabolic process nucleic acid metabolic process chromosome organization DNA conformation change cellular component organization DNA topological change organelle organization cellular component organization or biogenesis nucleobase-containing compound metabolic process DNA replication metabolic process cellular process primary metabolic process DNA metabolic process macromolecule metabolic process nucleic acid metabolic process chromosome organization DNA conformation change cellular component organization DNA topological change organelle organization cellular component organization or biogenesis cell cycle chromosome segregation cell cycle process	membrane-bounded organelle intracellular anatomical structure nucleus membrane-enclosed lumen intracellular membraneless organelle intracellular membrane-bounded organelle nucleolus intracellular organelle lumen intracellular organelle cellular anatomical structure organelle lumen organelle membraneless organelle nuclear lumen membrane-bounded organelle intracellular anatomical structure nucleus membrane-enclosed lumen intracellular membraneless organelle intracellular membrane-bounded organelle nucleolus intracellular organelle lumen intracellular organelle cellular anatomical structure organelle lumen organelle membraneless organelle nuclear lumen chromosome

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
D [auth A]	IPR011010	DNA breaking-rejoining enzyme, catalytic core	Homologous Superfamily
D [auth A]	IPR001631	DNA topoisomerase I	Family
D [auth A]	IPR008336	DNA topoisomerase I, DNA binding, eukaryotic-type	Domain
D [auth A]	IPR014711	DNA topoisomerase I, catalytic core, alpha-helical subdomain, eukaryotic-type	Homologous Superfamily
D [auth A]	IPR013030	DNA topoisomerase I, DNA binding, N-terminal domain 2	Homologous Superfamily
D [auth A]	IPR013499	DNA topoisomerase I, eukaryotic-type	Domain
D [auth A]	IPR051062	DNA topoisomerase IB	Family
D [auth A]	IPR036202	DNA topoisomerase I, DNA binding, eukaryotic-type, N-terminal domain superfamily	Homologous Superfamily
D [auth A]	IPR013500	DNA topoisomerase I, catalytic core, eukaryotic-type	Domain
D [auth A]	IPR013034	DNA topoisomerase I, DNA binding, N-terminal domain 1	Homologous Superfamily
E [auth B]	IPR011010	DNA breaking-rejoining enzyme, catalytic core	Homologous Superfamily
E [auth B]	IPR025834	Topoisomerase I C-terminal domain	Domain
E [auth B]	IPR018521	DNA topoisomerase I, active site	Active Site
E [auth B]	IPR051062	DNA topoisomerase IB	Family
E [auth B]	IPR014727	DNA topoisomerase I, catalytic core, alpha/beta subdomain	Homologous Superfamily

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.