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Transcription of chromosomal rRNA genes by both RNA polymerase I and II in yeast uaf30 mutants lacking the 30 kDa subunit of transcription factor UAF
Author(s) -
Siddiqi Imran N.,
Dodd Jonathan A.,
Vu Loan,
Eliason Kristilyn,
Oakes Melanie L.,
Keener John,
Moore Roger,
Young Mary K.,
Nomura Masayasu
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.16.4512
Subject(s) - biology , rna polymerase i , rna polymerase ii , transcription (linguistics) , genetics , transcription factor ii d , gene , rna polymerase , general transcription factor , rna polymerase ii holoenzyme , microbiology and biotechnology , rna polymerase iii , ribosomal rna , rna , promoter , gene expression , linguistics , philosophy
UAF, a yeast RNA polymerase I transcription factor, contains Rrn5p, Rrn9p, Rrn10p, histones H3 and H4, and uncharacterized protein p30. Mutants defective in RRN5 , RRN9 or RRN10 are unable to transcribe rDNA by polymerase I and grow extremely slowly, but give rise to variants able to grow by transcribing chromosomal rDNA by polymerase II. Thus, UAF functions as both an activator of polymerase I and a silencer of polymerase II for rDNA transcription. We have now identified the gene for subunit p30. This gene, UAF30 , is not essential for growth, but its deletion decreases the cellular growth rate. Remarkably, the deletion mutants use both polymerase I and II for rDNA transcription, indicating that the silencer function of UAF is impaired, even though rDNA transcription by polymerase I is still occurring. A UAF complex isolated from the uaf30 deletion mutant was found to retain the in vitro polymerase I activator function to a large extent. Thus, Uaf30p plays only a minor role in its activator function. Possible reasons for slow growth caused by uaf30 mutations are discussed.