In vitro transcribed SV40 minichromosomes, as the bulk minichromosomes, have a low level of unconstrained negative supercoils.
The method for detecting the small fraction (1%) of transcriptionally active SV40 minichromosomes, in the presence of the bulk minichromosomes, (14) has been applied to directly analyze the topology of transcribed and non-transcribed minichromosomal DNA. We show here that DNA of both transcribed and non-transcribed minichromosomes have the same number of supercoils which are constrained by nucleosomes. In addition, minichromosomal DNA of both fractions have a low level of unconstrained supercoils (1-2 extra supercoils) which can be relaxed in vitro by topoisomerase I.
Choder
M
M
Department of Genetics, Weizmann Institute of Science, Rehovot, Israel.
Aloni
Y
Y
D002738:Chloroquine; D004278:DNA, Superhelical / Q000648:ultrastructure*; D004279:DNA, Viral / Q000648:ultrastructure*; D004587:Electrophoresis, Agar Gel; D009707:Nucleosomes / Q000648:ultrastructure; D013539:Simian virus 40 / Q000235:genetics* / Q000648:ultrastructure; D014158:Transcription, Genetic
D004278:DNA, Superhelical; D004279:DNA, Viral; D009707:Nucleosomes; D002738:Chloroquine