DNA topoisomerases (or topoisomerases) are enzymes that catalyze changes in the topological state of DNA, interconverting relaxed and supercoiled forms, linked (catenated) and unlinked species, and knotted and unknotted DNA.[1][2] Topological issues in DNA arise due to the intertwined nature of its double-helical structure, which, for example, can lead to overwinding of the DNA duplex during DNA replication and transcription. If left unchanged, this torsion would eventually stop the DNA or RNA polymerases involved in these processes from continuing along the DNA helix. A second topological challenge results from the linking or tangling of DNA during replication. Left unresolved, links between replicated DNA will impede cell division. The DNA topoisomerases prevent and correct these types of topological problems. They do this by binding to DNA and cutting the sugar-phosphate backbone of either one (type I topoisomerases) or both (type II topoisomerases) of the DNA strands. This transient break allows the DNA to be untangled or unwound, and, at the end of these processes, the DNA backbone is resealed. Since the overall chemical composition and connectivity of the DNA do not change, the DNA substrate and product are chemical isomers, differing only in their topology.
^McKie SJ, Neuman KC, Maxwell A (April 2021). "DNA topoisomerases: Advances in understanding of cellular roles and multi-protein complexes via structure-function analysis". BioEssays. 43 (4): e2000286. doi:10.1002/bies.202000286. PMC 7614492. PMID 33480441. S2CID 231679533.
^Sutormin DA, Galivondzhyan AK, Polkhovskiy AV, Kamalyan SO, Severinov KV, Dubiley SA (2021-03-15). "Diversity and Functions of Type II Topoisomerases". Acta Naturae. 13 (1): 59–75. doi:10.32607/actanaturae.11058. PMC 8084294. PMID 33959387.
DNA topoisomerases (or topoisomerases) are enzymes that catalyze changes in the topological state of DNA, interconverting relaxed and supercoiled forms...
Type II topoisomerases are topoisomerases that cut both strands of the DNA helix simultaneously in order to manage DNA tangles and supercoils. They use...
Topoisomerase inhibitors are chemical compounds that block the action of topoisomerases, which are broken into two broad subtypes: type I topoisomerases...
Topoisomerase IV is one of two Type II topoisomerases in bacteria, the other being DNA gyrase. Like gyrase, topoisomerase IV is able to pass one double-strand...
In molecular biology Type I topoisomerases are enzymes that cut one of the two strands of double-stranded DNA, relax the strand, and reanneal the strand...
simply gyrase, is an enzyme within the class of topoisomerase and is a subclass of Type II topoisomerases that reduces topological strain in an ATP dependent...
DNA topoisomerase 1 is an enzyme that in humans is encoded by the TOP1 gene. It is a DNA topoisomerase, an enzyme that catalyzes the transient breaking...
DNA topoisomerase 2-beta is an enzyme that in humans is encoded by the TOP2B gene. This gene encodes a DNA topoisomerase, an enzyme that controls and alters...
Three topoisomerase enzymes are involved in this process: Type IA Topoisomerase, Type IB Topoisomerase, and Type II Topoisomerase. Type I Topoisomerase unwinds...
groups have been identified as the main components of the scaffold: DNA topoisomerase IIα, condensins, and the KIF4A kinesin. When these proteins are removed...
DNA topoisomerase IIα is a human enzyme encoded by the TOP2A gene. Topoisomerase IIα relieves topological DNA stress during transcription, condenses chromosomes...
This structure is also found in the catalytic domains of topoisomerase Ia, topoisomerase II, the OLD-family nucleases and DNA repair proteins related...
etoposide and teniposide. Topoisomerase inhibitors are drugs that affect the activity of two enzymes: topoisomerase I and topoisomerase II. When the DNA double-strand...
gyrase does in fact have topoisomerase type II activity; thus, with it being a homologue of topoisomerase IV (also having topoisomerase II activity) we expect...
and RNA production. Cytotoxicity is primarily due to inhibition of topoisomerase II after the enzyme induces a break in DNA, preventing religation of...
Specifically, they inhibit the ligase activity of the type II topoisomerases, DNA gyrase and topoisomerase IV, which cut DNA to introduce supercoiling, while leaving...
Although topoisomerase V is useful in this case, finding other hyperthermophiles that have topoisomerase V has proven difficult. This lack of topoisomerase V...
DNA topoisomerase 3-alpha is an enzyme that in humans is encoded by the TOP3A gene. This gene encodes a DNA topoisomerase, an enzyme that controls and...
Use during pregnancy will likely harm the fetus. Etoposide is in the topoisomerase inhibitor family of medication. It is believed to work by damaging DNA...
Austin is a British molecular biologist known for her work on human DNA topoisomerase enzymes. She is a Professor of Molecular Biology at the Institute for...
I topoisomerase that introduces positive supercoils into DNA, contrary to the typical negative supercoils introduced by the type II topoisomerase DNA...
Hycamtin among others, is a chemotherapeutic agent medication that is a topoisomerase inhibitor. It is a synthetic, water-soluble analog of the natural chemical...
Topoisomerase-based cloning (TOPO cloning) is a molecular biology technique in which DNA fragments are cloned into specific vectors without the requirement...
can result in harm to the baby. Irinotecan is a topoisomerase inhibitor—it blocks the topoisomerase I enzyme, resulting in DNA damage and cell death...
individuals with SLE. The antigenic target of anti-Scl-70 antibodies is topoisomerase I. Although anti-Jo-1 antibodies are often included with ANAs, they...
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