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

Neelam Desai1, Jaehoon Lee, Rajendra Upadhya

  • 1Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA.

The Journal of Biological Chemistry
|December 14, 2004
PubMed

Insights

The study reveals how Maf1 protein represses RNA polymerase III transcription in yeast. It identifies two key steps involving transcription factor IIIB and polymerase III recruitment, suggesting a non-stoichiometric mechanism.

Area of Science:

  • Molecular Biology
  • Yeast Genetics
  • Gene Regulation

Background:

  • Maf1 is a key regulator of RNA polymerase III transcription in Saccharomyces cerevisiae.
  • Diverse cellular signals converge on Maf1 to induce transcriptional repression.
  • Maf1-dependent repression is believed to involve common downstream inhibitory effects on the RNA polymerase III machinery.

Purpose of the Study:

  • To investigate the molecular mechanisms underlying Maf1-dependent repression of RNA polymerase III transcription.
  • To define the specific steps inhibited by Maf1 during transcriptional repression.
  • To explore the role of Brf1 and interactions with Maf1 in this process.

Main Methods:

  • Chlorpromazine (CPZ) treatment to induce Maf1-dependent repression.
  • Analysis of transcription factor IIIB (TFIIIB) assembly and RNA polymerase III recruitment.
  • Co-immunoprecipitation assays to study protein interactions.

Main Results:

  • CPZ-induced repression involves inhibition of TFIIIB.DNA complex assembly and RNA polymerase III recruitment.
  • Brf1 was identified as a target of repression.
  • Maf1 interacts with Brf1 and RNA polymerase III, suggesting a role in inhibiting complex assembly and polymerase recruitment.
  • Maf1 does not differentially sequester Brf1 or RNA polymerase III under repressing conditions.

Conclusions:

  • Maf1 represses RNA polymerase III transcription through at least two distinct steps.
  • Maf1 likely functions via a non-stoichiometric mechanism to regulate transcription.

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