Showing papers by "Jean-Louis Mandel published in 1973"
TL;DR: The transcription in vitro of twisted circular double-stranded SV40 DNA Form I by purified calf thymus AI and B RNA polymerases is studied and the lengths of the RNA’s synthesized by these enzymes are reported on.
16 citations
01 Jan 1973
TL;DR: It is clear that the possible specificity of the animal enzymes cannot be unequivocally demonstrated using ordinary preparations of DNA’s, since all of them contain a high number of single-stranded nicks, acting as efficient non-specific initiation sites.
Abstract: The multiplicity and different intranuclear localizations of DNA-dependent RNA polymerases have suggested that gene expression in animal cells is regulated, at least in part, by distinct RNA polymerases with different template specificities [1]. One of the most direct ways to support this hypothesis would be to show in vitro that the various purified enzymes specifically transcribe different parts of the deproteinized chromosomal DNA. A first step in such a study is to ask whether the purified enzymes alone can in fact initiate RNA synthesis on an intact double-stranded DNA, or whether the presence of additional initiation factor(s), similar to the E. coli σ factor [2, 3] is (are) required. Previous studies involving normal calf thymus DNA preparations and the initiation inhibitor AF/013 [4–7] have suggested that purified AI and B enzymes initiate at different sites on calf thymus DNA, and that the B enzymes could in fact initiate on “true” double-stranded regions of the DNA while AI enzyme could lack an initiation factor. It is nevertheless clear that the possible specificity of the animal enzymes cannot be unequivocally demonstrated using these ordinary preparations of DNA’s, since all of them contain a high number of single-stranded nicks (“high” compared to the expected number of true promoter sites), acting as efficient non-specific initiation sites [8, 9].
3 citations