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Protein Degradation of RNA Polymerase II-Association Factor 1(PAF1) Is Controlled by CNOT4 and 26S Proteasome

Hwa-Young Sun1, Nari Kim1, Cheol-Sang Hwang1

  • 1Department of Life Sciences, Pohang University of Science and Technology, Pohang, Korea.

Plos One
|May 2, 2015
PubMed

Insights

The CCR4-NOT complex component CNOT4 targets PAF1 for degradation via the 26S proteasome. This process requires nuclear localization but not chromatin binding, regulating PAF1 protein levels.

Area of Science:

  • Molecular Biology
  • Gene Regulation
  • Protein Degradation

Background:

  • The Polycomb Repressive Complex Associated Factor (PAF) complex (PAFc) is crucial for transcriptional regulation.
  • PAFc components, including PAF1, interact to control transcription from initiation to termination.
  • Understanding the regulation of PAFc component stability is vital for comprehending transcriptional control.

Purpose of the Study:

  • To elucidate the mechanism regulating PAF1 protein degradation.
  • To identify factors controlling PAF1 protein stability within the PAF complex.

Main Methods:

  • Investigated PAF1 protein degradation using CNOT4 expression.
  • Analyzed PAF1 polyubiquitination and 26S proteasome-mediated degradation.
  • Utilized nucleus localization signal (NLS)-deficient PAF1 mutants to assess localization requirements.

Main Results:

  • CNOT4 negatively regulates PAF1 protein levels.
  • CNOT4 promotes PAF1 polyubiquitination and subsequent 26S proteasome degradation.
  • PAF1 degradation by CNOT4 requires nuclear localization but not chromatin binding.

Conclusions:

  • CNOT4 controls the degradation of nuclear, chromatin-unbound PAF1 via the 26S proteasome.
  • This mechanism provides specific regulation of PAF1 protein levels within the PAF complex.
  • The findings offer insights into the dynamic regulation of transcriptional machinery.

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