Open AccessRibosomal gene promoter domains can function as artificial enhancers of RNA polymerase I transcription, supporting a promoter origin for natural enhancers in Xenopus.
Author(s) -
Craig S. Pikaard
Publication year - 1994
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.91.2.464
Subject(s) - enhancer , enhancer rnas , biology , xenopus , promoter , upstream activating sequence , rna polymerase ii , transcription (linguistics) , microbiology and biotechnology , gene , transcription factor , spacer dna , genetics , ribosomal rna , gene expression , linguistics , philosophy , internal transcribed spacer
Enhancers of RNA polymerase I transcription in higher eukaryotes are repetitive elements within the intergenic spacers of rRNA genes. In Xenopus and mouse, enhancers and the gene promoter bind the activator protein, upstream binding factor, and in Xenopus, enhancers also share sequence similarity with an upstream domain of the promoter. This upstream promoter domain can act as an efficient enhancer when polymerized and cloned adjacent to a ribosomal gene promoter injected into oocytes. A core promoter domain lacking similarity with spacer sequences in Xenopus laevis but analogous to a repeated sequence in Xenopus borealis can also function as an enhancer. These data demonstrate functional relatedness between the promoter and enhancers, supporting the hypothesis that enhancers could have evolved from duplicated promoter domains that bind essential transcription factors. The ability of upstream binding factor to bind enhancers inactivated by mutation suggests that upstream binding factor binding alone cannot explain enhancer function.