Positive modulation of RNA polymerase III transcription by ribosomal proteins.

Dipartimento di Biochimica e Biologia Molecolare, Universita degli Studi di Parma, Viale G.P. Usberti 23/A, 43100 Parma, Italy. giorgio.dieci@unipr.it
A yeast nuclear fraction of unknown composition, named TFIIIE, was reported previously to enhance transcription of tRNA and 5S rRNA genes in vitro. We show that TFIIIE activity co-purifies with a specific subset of ribosomal proteins (RPs) which, as revealed by chromatin immunoprecipitation analysis, generally interact with tRNA and 5S rRNA genes, but not with a Pol II-specific promoter. Only Rpl6Ap and Rpl6Bp, among the tested RPs, were found associated to a TATA-containing tRNA(Ile)(TAT) gene. The RPL6A gene also emerged as a strong multicopy suppressor of a conditional mutation in the basal transcription factor TFIIIC, while RPL26A and RPL14A behaved as weak suppressors. The data delineate a novel extra-ribosomal role for one or a few RPs which, by influencing 5S rRNA and tRNA synthesis, could play a key role in the coordinate regulation of the different sub-pathways required for ribosome biogenesis and functionality.
Mesh Terms:
Chromatin Immunoprecipitation, Gene Expression Regulation, Fungal, Mutation, Promoter Regions, Genetic, RNA Polymerase III, RNA, Ribosomal, 5S, RNA, Transfer, Ile, Ribosomal Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Transcription Factors, TFIII, Transcription, Genetic
Biochem. Biophys. Res. Commun. Feb. 06, 2009; 379(2);489-93 [PUBMED:19116144]
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