RNA polymerase switch in transcription of yeast rDNA: role of transcription factor UAF (upstream activation factor) in silencing rDNA transcription by RNA polymerase II

Transcription factor UAF (upstream activation factor) is required for a high level of transcription, but not for basal transcription, of rDNA by RNA polymerase I (Pol I) in the yeast Saccharomyces cerevisiae. RRN9 encodes one of the UAF subunits. We have found that rrn9 deletion mutants grow extreme...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1999-04, Vol.96 (8), p.4390-4395
Main Authors: Vu, L, Siddiqi, I, Lee, B.S, Josaitis, C.A, Nomura, M
Format: Article
Language:English
Subjects:
Biochemistry
Biological Sciences
Chromatin
Crosses, Genetic
deletions
Deoxyribonucleic acid
Diploidy
DNA
DNA, Ribosomal - genetics
DNA, Ribosomal - metabolism
DNA-Binding Proteins - metabolism
DNA-directed RNA polymerase
Enzymes
Gene Deletion
Genes
Genetic mutation
genetic regulation
Haploidy
Mutagenesis
mutants
Mutation
Phenotypes
Plasmids
Ribonucleic acid
Ribosomal DNA
ribosomal RNA
RNA
RNA Polymerase I - metabolism
RNA Polymerase II - metabolism
Saccharomyces cerevisiae
Saccharomyces cerevisiae - enzymology
Saccharomyces cerevisiae - genetics
Saccharomyces cerevisiae - growth & development
Saccharomyces cerevisiae Proteins
Templates, Genetic
transcription (genetics)
transcription factors
Transcription Factors - metabolism
Transcription, Genetic
Yeast
Yeasts
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Summary:Transcription factor UAF (upstream activation factor) is required for a high level of transcription, but not for basal transcription, of rDNA by RNA polymerase I (Pol I) in the yeast Saccharomyces cerevisiae. RRN9 encodes one of the UAF subunits. We have found that rrn9 deletion mutants grow extremely slowly but give rise to faster growing variants that can grow without intact Pol I, synthesizing rRNA by using RNA polymerase II (Pol II). This change is reversible and does not involve a simple mutation. The two alternative states, one suitable for rDNA transcription by Pol I and the other favoring rDNA transcription by Pol II, are heritable not only in mitosis, but also in meiosis. Thus, S. cerevisiae has an inherent ability to transcribe rDNA by Pol II, but this transcription activity is silenced in normal cells, and UAF plays a key role in this silencing by stabilizing the first state.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.96.8.4390