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RAD6-dependent DNA repair is linked to modification of PCNA by ubiquitin and SUMO

Carsten Hoege1, Boris Pfander, George-Lucian Moldovan

  • 1Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18a, 82152 Martinsried, Germany.

Nature
|September 13, 2002
PubMed

Insights

The RAD6 DNA repair pathway involves ubiquitination and SUMOylation of proliferating cell nuclear antigen (PCNA). These modifications, occurring at the same site, differentially impact DNA damage resistance and are crucial for repair in yeast and humans.

Area of Science:

  • Molecular Biology
  • DNA Repair Mechanisms
  • Ubiquitin Signaling

Background:

  • The RAD6 pathway is essential for post-replicative DNA repair in eukaryotes.
  • Key components include RAD6, MMS2-UBC13, RAD18, and RAD5, but pathway regulation is not fully understood.

Purpose of the Study:

  • To investigate the involvement of UBC9 (a SUMO-conjugating enzyme) in the RAD6 pathway.
  • To identify substrates of the RAD6 pathway and their modifications.
  • To elucidate the functional consequences of these modifications on DNA repair.

Main Methods:

  • Chromatin recruitment analysis of pathway components.
  • Identification and characterization of proliferating cell nuclear antigen (PCNA) modifications.
  • Assays to assess DNA damage resistance and repair efficiency.

Main Results:

  • UBC9 is affiliated with the RAD6 pathway, and PCNA is a substrate.
  • PCNA undergoes mono-ubiquitination (RAD6/RAD18), K63-linked multi-ubiquitination (MMS2/UBC13/RAD5), and SUMOylation (UBC9) at the same lysine residue.
  • These modifications differentially affect DNA damage resistance.
  • Damage-induced PCNA ubiquitination is essential for DNA repair and conserved in yeast and humans.

Conclusions:

  • PCNA is a central hub for multiple post-translational modifications within the RAD6 DNA repair pathway.
  • These modifications, though acting on the same residue, confer distinct functions related to DNA damage tolerance and repair.
  • The findings highlight conserved mechanisms of DNA repair regulation across species.

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