Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.99.1.3 (topoisomerase)
 9,911 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In addition to its fundamental role of nucleating the formation of stable transcription complexes, the Xenopus laevis 5S RNA specific transcription factor, TFIIIA, promotes a variety of DNA-associated metabolic reactions. We report that TFIIIA can induce a DNA supercoiling catalyzed by the Xenopus laevis S-150 cell-free extract on plasmids containing a single copy of the Xenopus 5S RNA gene (somatic-type). Stimulated supercoiling occurs in the presence of high concentrations of ATP (4 mM) and at a factor to DNA ratio of 1 through a mechanism most likely involving type I topoisomerase. The highest level of stimulated supercoiling occurs when TFIIIA is incubated with DNA prior to the addition of the S-150 extract. Taken together, the experiments outlined in this report establish a reliable and seminal system in which TFIIIA-induced DNA supercoiling can be observed reproducibly.
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PMID:Reaction parameters of TFIIIA-induced supercoiling catalyzed by a Xenopus laevis cell-free extract. 231 14

We report that TFIIIA, the positive transcription factor of the 5S RNA gene, induces DNA gyration in Xenopus oocyte extracts. The reaction uses one molecule of TFIIIA per molecule of DNA and is highly specific for 5S DNA plasmids. DNA gyration also requires the oocyte supernatant, ATP, and Mg2+, and is inhibited by novobiocin, suggesting that it is catalyzed by a type II DNA topoisomerase. The chromatin assembled with TFIIIA is dynamic and rapidly relaxed by novobiocin; the chromatin assembled without TFIIIA is static and unaffected by novobiocin. The torsionally strained DNA is produced in a novel concerted reaction: all of the 5S DNA molecules gyrate at TFIIIA-5S DNA ratios equal to or above 1, and none of them gyrate at TFIIIA-5S DNA ratios below 1. We discuss the biological implications of this eukaryotic DNA gyration.
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PMID:The positive transcription factor of the 5S RNA gene induces a 5S DNA-specific gyration in Xenopus oocyte extracts. 341 56

Novobiocin has been shown to inhibit class III gene transcription from both chromatin and non-chromatin templates. Since novobiocin is a well characterized inhibitor of type II DNA topoisomerases, it has been postulated that a gyrase activity is necessary for transcription. Using DNase I footprinting, we show here that novobiocin inhibits the specific binding of polymerase III transcription factors TFIIIA and TFIIIC to the promoters of the 5S RNA and VA RNA genes, respectively. Concentrations of novobiocin employed were comparable to those necessary to inhibit HeLa topoisomerase II. In vitro transcription assays, performed under equivalent conditions, demonstrated that similar novobiocin concentrations were necessary for transcription inhibition. These results strongly suggest that novobiocin interferes with transcription by inhibiting specific protein-DNA interactions.
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PMID:Novobiocin interferes with the binding of transcription factors TFIIIA and TFIIIC to the promoters of class III genes. 358 99