title: Point mutation analysis of the Xenopus laevis RNA polymerase I core promoter.
abstract: The core region of the Xenopus laevis pre-ribosomal RNA promoter was subjected to point mutation analysis. A total of 27 point mutants within a 78 base pair region from -64 to +14, (relative to the start of transcription at +1), were assayed by oocyte microinjection. The results locate the 3' boundary of the core promoter at +4 and the 5' boundary at between -33 and -39 and suggest that this region of the Xenopus promoter is generally similar in organisation to mammalian core promoters. In particular, the conserved guanidine nucleotides at -7 and -16 are clearly essential for promoter function. The data suggest that interactions between the transcription machinery and the promoter occur in four distinct regions around +2 to +4, -7, -17 to -20 and -28 to -33. This particular periodicity of functionally important nucleotides is consistent with a model in which all protein-DNA interactions take place from predominantly one side of the DNA helix.
authors.affiliation: Biophysics Laboratories, Portsmouth Polytechnic, UK.
authors.forename: S
authors.initials: S
authors.lastname: Firek
authors.forename: C
authors.initials: C
authors.lastname: Read
authors.forename: D R
authors.initials: DR
authors.lastname: Smith
authors.forename: T
authors.initials: T
authors.lastname: Moss
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D004275:DNA, Ribosomal / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012318:RNA Polymerase I / Q000235:genetics*; D012335:RNA, Ribosomal / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D013379:Substrate Specificity; D014982:Xenopus laevis / Q000235:genetics
chemical_list: D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; D012318:RNA Polymerase I