Protein kinase A regulates RNA polymerase III transcription through the nuclear localization of Maf1

Robyn D. Moir, JaeHoon Lee, Rebecca A. Haeusler, Neelam Desai, David R. Engelke, Ian M. Willis

Research output: Contribution to journalArticle

100 Citations (Scopus)

Abstract

Maf1 is an essential and specific mediator of transcriptional repression in the RNA polymerase (pol) III system. Maf1-dependent repression occurs in response to a wide range of conditions, suggesting that the protein itself is targeted by the major nutritional and stress-signaling pathways. We show that Maf1 is a substrate for cAMP-dependent PKA in vitro and is differentially phosphorylated on PKA sites in vivo under normal versus repressing conditions. PKA activity negatively regulates Maf1 function because strains with unregulated high PKA activity block repression of pol III transcription in vivo, and strains lacking all PKA activity are hyperrepressible. Nuclear accumulation of Maf1 is required for transcriptional repression and is regulated by two nuclear localization sequences in the protein. An analysis of PKA phosphosite mutants shows that the localization of Maf1 is affected via the N-terminal nuclear localization sequence. In particular, mutations that prevent phosphorylation at PKA consensus sites promote nuclear accumulation of Maf1 without inducing repression. These results indicate that negative regulation of Maf1 by PKA is achieved by inhibiting its nuclear import and suggest that a PKA-independent activation step is required for nuclear Maf1 to function in the repression of pol III transcription. Finally, we report a previously undescribed phenotype for Maf1 in tRNA gene-mediated silencing of nearby RNA pol Il transcription.

Original languageEnglish (US)
Pages (from-to)15044-15049
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume103
Issue number41
DOIs
StatePublished - Oct 10 2006

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RNA Polymerase III
Cyclic AMP-Dependent Protein Kinases
Cell Nucleus Active Transport
Gene Silencing
DNA-Directed RNA Polymerases
Transfer RNA
Proteins
Phosphorylation
Phenotype
Mutation
In Vitro Techniques

Keywords

  • Nuclear import
  • Phosphorylation
  • tRNA biosynthesis

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

Protein kinase A regulates RNA polymerase III transcription through the nuclear localization of Maf1. / Moir, Robyn D.; Lee, JaeHoon; Haeusler, Rebecca A.; Desai, Neelam; Engelke, David R.; Willis, Ian M.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 103, No. 41, 10.10.2006, p. 15044-15049.

Research output: Contribution to journalArticle

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