Abstract
Nhp6A and Nhp6B are HMG1-like proteins required for the growth of S. cerevisiae at elevated temperatures. We show that the conditional lethality of an nhp6 strain results from defective transcription of SNR6 (U6 snRNA) by RNA polymerase III. Overexpression of U6 snRNA or Brf1, a limiting component of TFIIIB, and an activating mutation (PCF1-1) in TFIIIC were each found to suppress the nhp6 growth defect. Additionally, U6 snRNA levels, which are reduced over 10-fold in nhp6 cells at 37 degrees C, were restored by Brf1 overexpression and by PCF1-1. Nhp6A protein specifically enhanced TFIIIC-dependent, but not TATA box-dependent, SNR6 transcription in vitro by facilitating TFIIIC binding to the SNR6 promoter. Thus, Nhp6 has a direct role in transcription complex assembly at SNR6.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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DNA, Fungal / genetics
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DNA, Fungal / metabolism
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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Gene Expression Regulation, Fungal*
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Genes, Fungal / genetics
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Genes, Lethal / genetics
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HMGN Proteins
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High Mobility Group Proteins / metabolism*
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Phenotype
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Promoter Regions, Genetic / genetics
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Protein Binding
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RNA Polymerase III / chemistry
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RNA Polymerase III / metabolism*
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RNA, Fungal / biosynthesis
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RNA, Fungal / genetics
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RNA, Ribosomal, 5S / biosynthesis
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RNA, Ribosomal, 5S / genetics
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RNA, Small Nuclear / genetics*
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RNA, Small Nuclear / metabolism
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RNA, Transfer / biosynthesis
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RNA, Transfer / genetics
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Saccharomyces cerevisiae / enzymology
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Saccharomyces cerevisiae / genetics*
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Saccharomyces cerevisiae / growth & development
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins*
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Suppression, Genetic / genetics
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Temperature
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Transcription Factor TFIIIB
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Transcription Factors / genetics
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Transcription Factors / metabolism
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Transcription Factors, TFIII / genetics
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Transcription Factors, TFIII / metabolism
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Transcription, Genetic / genetics
Substances
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BRF1 protein, S cerevisiae
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DNA, Fungal
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DNA-Binding Proteins
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Fungal Proteins
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HMGN Proteins
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High Mobility Group Proteins
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NHP6A protein, S cerevisiae
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NHP6B protein, S cerevisiae
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Nuclear Proteins
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RNA, Fungal
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RNA, Ribosomal, 5S
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RNA, Small Nuclear
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Saccharomyces cerevisiae Proteins
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Transcription Factor TFIIIB
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Transcription Factors
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Transcription Factors, TFIII
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U6 small nuclear RNA
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transcription factor TFIIIC
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RNA, Transfer
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RNA Polymerase III