Topoisomerases are ubiquitously expressed enzymes that overcome topological problems in genomic DNA, which can result from DNA replication, transcription and repair. Common problems such as overwinding (positive supercoiling), knots and tangles are resolved by topoisomerases by catalyzing the breaking of one or two strands of DNA.
Topoisomerase type I enzymes cut just one strand of the DNA double helix, and therefore relax supercoiling of the DNA. Four genes encode Type I topoisomerases, which include nuclear topoisomerase I (TOP1) and mitochondrial topoisomerase I (TOP1MT). Type I enzymes can also be sub-divided into Types A and B based on their different catalytic mechanism for generating single DNA strand breaks. TOP1 and TOP1MT are both type 1B since they form 3'-phosphotyrosyl bonds. Camptothecin is a natural product inhibitor of TOP1 that has led to the discovery of derivatives that are clinically used anticancer drugs. Such inhibitors trap the enzyme in a cleavage complex with DNA. Type II topoisomerases (IIA and IIB) are particular important for the disentanglement of DNA, which is overcome by generating double stranded DNA breaks. Dysregulation of type II enzymes can therefore have a potentially significant genotoxic effect. There is a broad range of topoisomerase II inhibitors that are used clinically as therapeutically in cancer.View all products for DNA Topoisomerases »
|Gene||Species||Gene Symbol||Gene Accession No.||Protein Accession No.|
|Topoisomerase I (mitochondrial)||Human||TOP1MT||NM_052963||Q969P6|
|View all Topoisomerase Gene Data »|
Literature for DNA Topoisomerases
A collection of over 750 products for cancer research, the guide includes research tools for the study of:
- Cancer Metabolism
- Epigenetics in Cancer
- Receptor Signaling
- Cell Cycle and DNA Damage Repair
- Invasion and Metastasis
In normal cells, each stage of the cell cycle is tightly regulated, however in cancer cells many genes and proteins that are involved in the regulation of the cell cycle are mutated or over expressed. Adapted from the 2015 Cancer Product Guide, Edition 3, this poster summarizes the stages of the cell cycle and DNA repair. It also highlights strategies for enhancing replicative stress in cancer cells to force mitotic catastrophe and cell death.Request copy | Download PDF | View all posters
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