Two steps in Maf1-dependent repression of transcription by RNA polymerase III

Neelam Desai, Jae Hoon Lee, Rajendra Upadhya, Yaya Chu, Robyn D. Moir, Ian M. Willis

Research output: Contribution to journalArticle

80 Scopus citations

Abstract

In Saccharomyces cerevisiae, Maf1 is essential for mediating the repression of transcription by RNA polymerase (pol) III in response to diverse cellular conditions. These conditions activate distinct signaling pathways that converge at or above Maf1. Thus, Maf1-dependent repression is thought to involve a common set of downstream inhibitory effects on the pol III machinery. Here we provide support for this view and define two steps in Maf1-dependent transcriptional repression. We show that chlorpromazine (CPZ)-induced repression of pol III transcription is achieved by inhibiting de novo assembly of transcription factor (TF) IIIB onto DNA as well as the recruitment of pol III to preassembled TFIIIB·DNA complexes. Additionally Brf1 was identified as a target of repression in extracts of CPZ-treated cells. Maf1-Brf1 and Maf1-pol III interactions were implicated in the inhibition of TFIIIB·DNA complex assembly and polymerase recruitment by recombinant Maf1. Co-immunoprecipitation experiments confirmed these interactions in yeast extracts and demonstrated that Maf1 does not differentially sequester Brf1 or pol III under repressing conditions. The results suggest that Maf1 functions by a non-stoichiometric mechanism to repress pol III transcription.

Original languageEnglish (US)
Pages (from-to)6455-6462
Number of pages8
JournalJournal of Biological Chemistry
Volume280
Issue number8
DOIs
StatePublished - Feb 25 2005

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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