5.6.2.1: DNA topoisomerase
This is an abbreviated version!
For detailed information about DNA topoisomerase, go to the full flat file.
Word Map on EC 5.6.2.1
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5.6.2.1
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camptothecins
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supercoiled
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strand
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etoposide
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topotecan
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leukemia
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novobiocin
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dna-damaging
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unwind
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medicine
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drug development
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aphidicolin
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etoposide-induced
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pharmacology
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holliday
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diagnostics
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norfloxacin
- 5.6.2.1
- camptothecins
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supercoiled
- strand
- etoposide
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poison
- topotecan
- irinotecan
- leukemia
- chromatin
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cleavable
- doxorubicin
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single-stranded
- fluoroquinolones
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quinolone
- ovarian
- duplex
- colorectal
- ciprofloxacin
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ii-mediated
- fork
- helicase
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schedule
- cisplatin
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decatenation
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antiproliferative
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checkpoint
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superhelical
- novobiocin
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intercalation
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breakage
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dna-damaging
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unwind
- neutropenia
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dose-limiting
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s-phase
- anthracyclines
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cross-resistance
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myelosuppression
- kinetoplast
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taxanes
- levofloxacin
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nalidixic
- mitoxantrone
- scleroderma
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rejoin
- analysis
- chk1
- medicine
- drug development
- aphidicolin
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etoposide-induced
- pharmacology
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holliday
- diagnostics
- norfloxacin
Reaction
ATP-independent breakage of single-stranded DNA, followed by passage and rejoining =
Synonyms
ATP-independent type I topoisomerase, AtTop1, bcTopo I, bcTopo IIIbeta, bi-subunit topoisomerase I, Bi-subunit topoisomerase IB, Ca-Top1, CrTop1, Dam DNA topoisomerase III, Deoxiribonucleate topoisomerase, Deoxiribonucleic topoisomerase, DNA Top IB, DNA topo I, DNA topoisomerase, DNA topoisomerase 1, DNA topoisomerase I, DNA topoisomerase I alpha, DNA topoisomerase I-B, DNA topoisomerase IB, DNA topoisomerase III, DNA topoisomerase IIIalpha, DNA topoisomerase type I, EC 5.99.1.2, EcTOP, ETOP, HssTopoI, HsTop1, hTop1p, hTopI, hTopo, htopo I, hTopo IIIalpha, hTopoI, human DNA topoisomerase I, human Top1, human topo I, human topoisomerase I, Isomerase, deoxiribonucleate topo-, Late protein H6, LdTop1, LdTOP1L, LdTOP1LS, LdTOP1S, LdTopIIIbeta, MimiTopIB, MsTopA, MtbTopA, mTopoI, MtTOP1, MttopoI, Nicking-closing enzyme, OjTop1, OlTop1, omega-Protein, OpTop1, PfTopI, PfTopoI, Poxviridae topoisomerase IB, Relaxing enzyme, Reverse gyrase, SiRe_1176, SsTop3, Swivelase, top I, Top1, TOP1alpha, TOP1mt, Top1p, TopA, TopI, TopIB, topo 1, Topo I, topo IB, topo V, topoI, Topoisomerase, topoisomerase 1, topoisomerase 1alpha, Topoisomerase I, topoisomerase I homolog, topoisomerase IB, topoisomerase III, topoisomerase IIIalpha, topoisomerase IIIbeta, topoisomerase IV, topoisomerase V, topoisomerase-I, topoIV, TopR1, TpI, Type I DNA topoisomerase, type I topoisomerase, type IA DNA topoisomerase, type IA topoisomerase, type IB topoisomerase, type IB topoisomerase V, Untwisting enzyme, Vaccinia DNA topoisomerase I, variola topoisomerase IB, vTopo, yeast DNA topoisomerase I, yeastTop1, YpTOP, YrdD, YTOP
ECTree
5.6.2.1 DNA topoisomeraseAdvanced search results
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results (Natural Substrates Products
Natural Substrates Products on EC 5.6.2.1 - DNA topoisomerase
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NATURAL SUBSTRATE 
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
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negatively supercoiled DNA
relaxed DNA
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TopR1 can relax negative supercoils without ATP, while the extent of positive supercoiling catalyzed by TopR1 is dependent on the stoichiometry, the ATP concentration, the NaCl concentration and the assay temperature
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supercoiled DNA
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reverse gyrase induces unwinding of synthetic four-way junctions as well as forked DNA substrates, following a mechanism independent of both the ATPase and the strand cutting activity of the enzyme. Reverse gyrase works like an ATP-independent helix-destabilizing protein specific for branched DNA structures
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supercoiled DNA
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reverse gyrase induces unwinding of synthetic four-way junctions as well as forked DNA substrates, following a mechanism independent of both the ATPase and the strand cutting activity of the enzyme. Reverse gyrase works like an ATP-independent helix-destabilizing protein specific for branched DNA structures
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supercoiled DNA
relaxed DNA
the enzyme relaxes the negative DNA supercoiling generated by RNA polymerase during transcription elongation
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additional information
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enzyme controls the topological state of DNA
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role in control of DNA topology including regulation of supercoiling and maintenance of genetic stability
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topoisomerase I works in concert with topoisomerase II to modulate the level of DNA supercoiling
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when enzyme expression is interfered with by a cognate double-stranded RNA injection, pleiotropic phenotypes with abnormalities in germ cell proliferation, oogenesis and embryogenesis appeare
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when enzyme expression is interfered with by a cognate double-stranded RNA injection, pleiotropic phenotypes with abnormalities in germ cell proliferation, oogenesis and embryogenesis appeare
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Drosophila sp. (in: flies)
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enzyme controls the topological state of DNA
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enzyme controls the topological state of DNA
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controls the DNA topology by cleaving and rejoining DNA strands and passing other DNA strands through the transient gaps, plays a crucial role in the regulation of the physiological function of the genome
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additional information
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plays a crucial role in controlling the physiological functions of DNA
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plays a direct role in the regulation of transcriptional initiation by acting as a repressor of the basal-level transcription
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role of topoisomerase I in DNA replication, transcription and recombination
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DNA structural alterations induced by UV lesions can be sufficient stimulus to induce cross-linking of topoisomerase I to cellular DNA
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Topo I is the first endogenous interaction partner for c-Jun in the regulation of cancer cell proliferation. Topo I and JNK-c Jun pathway cooperate in the regulation of eGFR gene expression and in the proliferation of HT-1080 cells
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additional information
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Cdc2-like kinases and DNA topoisomerase I regulate alternative splicing of tissue factor, TF, via phosphorylation of serine/arginine-rich proteins. Selective inhibition of Cdc2-like kinases and DNA topoisomerase I elicite distinct changes in TF biosynthesis in TNF-alpha-stimulated endothelial cells, which impact endothelial procoagulant activity, overview
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DNA topoisomerase IB catalyzes the relaxation of supercoiled DNA through the transient cleavage of one strand of a DNA duplex, molecular dynamics simulation of wild-type and mutant K681A enzymes, the N-terminal and C-terminal regions of the core domain show a slightly larger and a slightly smaller displacements, respectively, in the wild type than in the mutant enzyme, overview
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human cells can rapidly activate and deactivate DNA topoisomerase I in response to a signal molecule, the activity of DNA topoisomerase I is highly regulated in HuT 78 cells upon treatment with interleukin-2, overview
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reversible reaction. TopI produces a single strand break in DNA, allowing relaxation of DNA during its replication. The single strand break is then religated, thus restoring the DNA double strands. The enzymatic mechanism involves two sequential transesterification reactions. The cleavage reaction involves the active site Tyr723 acting as a nucleophile. A phenolic oxygen attacks a DNA phosphodiester bond, forming an intermediate in which the 3' end of the broken strand is covalently attached by an O4-phosphodiester bond to TopI tyrosine. The religation step consists of transesterification involving a nucleophilic attack by the hydroxyl oxygen at the 5' end of the broken strand. The equilibrium constant of the breakage and closure reactions is close to unity
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Top1 functionally interacts with splicing factor ASF/SF2, alternative splicing factor/splicing factor 2 modulating its the function to prevent genomic instability in S phase
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additional information
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human topoisomerase I is a dual-activity enzyme. First, it transiently nicks double-stranded DNA. Next, topo I is a kinase that phosphorylates SR proteins, essential splicing factors, and regulators of splicing composed of one or two RNA recognition motifs (RRMs) followed by the RS domain (RS) and containing numerous serine-arginine repeats. Topo I is one of several protein kinases that phosphorylate SR proteins, enzymes of both families, SRPK1 and CLK1
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the enzyme catalyzes the relaxation of supercoiled DNA during DNA replication and transcription
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additional information
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TopIIIbeta possesses a weak, ATP-independent relaxation activity towards negatively supercoiled DNA only
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additional information
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TopIIIbeta possesses a weak, ATP-independent relaxation activity towards negatively supercoiled DNA only
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additional information
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TopIIIbeta possesses a weak, ATP-independent relaxation activity towards negatively supercoiled DNA only
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additional information
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the topoisomerase and DNA repair activities reside in different parts of the protein and the DNA repair activity is dispensable for the topoisomerase catalytic activity
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topo V contains a signature motif of leucine-responsive regulatory proteins and therefore might also act as a transcriptional regulator, in addition to being a topoisomerase and an apurinic/apyrimidinic lyase
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enzyme controls the topological state of DNA
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the mycobacterial topoisomerase I physically interacts with its ribokinase both in vitro and in vivo with opposite effects on their respective function, overview. Interaction analysis, overview
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the mycobacterial topoisomerase I physically interacts with its ribokinase both in vitro and in vivo with opposite effects on their respective function, overview. Interaction analysis, overview
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topoisomerase I shows a negative interplay between MazF protein Rv1495. Through its C-terminal domain, MtbTopA physically interacts with and inhibits the mRNA cleavage activity of Rv1495, overview. Rv1495, in turn, inhibits the DNA cleavage activity of MtbTopA as well as its function of relaxation of supercoiled DNA
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the mycobacterial topoisomerase I physically interacts with its ribokinase both in vitro and in vivo with opposite effects on their respective function, overview. Interaction analysis, overview
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MsTopA stimulates the phosphorylating activity of Ms3759 on D-ribose, and physically interacts with its ribokinase both in vitro and in vivo with opposite effects on their respective function, overview. Interaction analysis, overview
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additional information
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topoisomerase I shows a negative interplay between MazF protein Rv1495. Through its C-terminal domain, MsTopA physically interacts with and inhibits the mRNA cleavage activity of Rv1495. Rv1495, in turn, inhibits the DNA cleavage activity of MsTopA as well as its function of relaxation of supercoiled DNA
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MstopoI carries out the DNA relaxation reaction in a processive fashion
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enzyme controls the topological state of DNA
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additional information
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enzyme controls the topological state of DNA
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additional information
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enzyme controls the topological state of DNA
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additional information
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topoisomerase I forms in vivo complexes with DNA substrates, the complexes are stabilized by irinotecan, which has DNA strand breaking ability, it leads to topisomerase poisoning and DNA damage, overview
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FOB1 affects DNA topoisomerase I in vivo cleavages in the enhancer region of the Saccharomyces cerevisiae ribosomal DNA locus. Binding to DNA of Fob1p itself may be the cause of the DNA topoisomerase I activity in the rDNA enhancer
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H2O2 induces topoisomerase I-mediated DNA damage and cell death. H2O2 promotes the trapping of topoisomerase I on oxidative DNA lesions to form TOP1-DNA cleavage complexes that contribute to H2O2 toxicity
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type I DNA topoisomerase from vaccinia virus, vTopo, forms a reversible covalent 3'-phosphotyrosyl linkage with a single strand of duplex DNA at the preferred sequence 5'-(C/T) CCTTp-/-N-1N-2N-3-3'. Site-specific DNA cleavage and ligation chemistry. Oscillation between an open and closed state of the covalently bound enzyme is likely important for regulating the number of DNA superhelical turns that are removed during the lifetime of the covalent complex with supercoiled substrates
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