Sequence-specific transactivators counteract topoisomerase II-mediated inhibition of in vitro transcription by RNA polymerases I and II.
An inhibitor of RNA polymerase II transcription in vitro has been purified from HeLa cell nuclear extracts. Partial amino acid sequences derived from the purified protein revealed that the inhibitor of transcription corresponded to human topoisomerase II. Order of addition experiments provided evidence indicating that topoisomerase II inhibited transcription by binding over the core promoter and blocking preinitiation complex formation. Topoisomerase II-mediated repression could be relieved by sequence-specific transcriptional activators, having different activating and/or DNA binding domains, but antirepression required a transcriptional activation function in addition to a DNA binding domain. Moreover, transcription by RNA polymerase I was also inhibited by topoisomerase II and this inhibition could be relieved by the RNA polymerase I transactivator UBF. These observations suggest that topoisomerase II may participate in a general repression of transcription which can be counteracted by transcriptional activators.
Brou
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C
Laboratoire de Génétique Moléculaire des Eucaryotes du CNRS, Unité 184 de Biologie Moléculaire et de Génie Génétique de l'INSERM, Faculté de Médecine, Strasbourg, France.
Kuhn
A
A
Staub
A
A
Chaudhary
S
S
Grummt
I
I
Davidson
I
I
Tora
L
L
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D012318:RNA Polymerase I / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012319:RNA Polymerase II / Q000037:antagonists & inhibitors* / Q000378:metabolism; D059005:Topoisomerase II Inhibitors; D015534:Trans-Activators / Q000378:metabolism*; D014158:Transcription, Genetic
D059005:Topoisomerase II Inhibitors; D015534:Trans-Activators; D004247:DNA; D012319:RNA Polymerase II; D012318:RNA Polymerase I; D004250:DNA Topoisomerases, Type II