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In Vitro Ubiquitination and Deubiquitination Assays of Nucleosomal Histones
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Physical and functional interactions of monoubiquitylated transactivators with the proteasome

Chase T Archer1, Lyle Burdine, Bo Liu

  • 1Division of Translational Research and Department of Internal Medicine, University of Texas-Southwestern Medical Center, Dallas, TX 75390-9185, USA.

The Journal of Biological Chemistry
|June 3, 2008
PubMed

Insights

Monoubiquitylation protects activators from proteasomal degradation, preventing transcription inhibition. This modification limits activator-ATPase complex interaction, preserving activator-DNA binding and gene transcription.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Gene Regulation

Background:

  • Proteasomal ATPases destabilize activator-DNA complexes, inhibiting transcription.
  • Monoubiquitylation of activators offers protection against this destabilization.

Purpose of the Study:

  • To investigate the protective mechanism of monoubiquitylation against proteasomal destabilization of activator-DNA complexes.
  • To elucidate how monoubiquitylation influences the interaction between activators and proteasomal ATPases.

Main Methods:

  • Novel label transfer techniques.
  • Chemical cross-linking assays.
  • Biochemical analysis of protein-protein interactions.

Main Results:

  • Ubiquitin directly contacts the proteasomal ATPase complex, specifically Rpn1 and Rpt1.
  • This interaction induces allosteric dissociation of the activator-DNA-ATPase complex.
  • Monoubiquitylation limits the duration of activator-ATPase complex interactions.

Conclusions:

  • Activator monoubiquitylation acts as a regulatory mechanism to control proteasomal activity.
  • This process prevents the unfolding and dissociation of activators from DNA by ATPases.
  • Monoubiquitylation ensures sustained activator-DNA complex stability and facilitates transcription.

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