Sequential post-translational modifications regulate damaged DNA-binding protein DDB2 function

Hidenori Kaneoka1, Kazuhiko Arakawa1, Yusuke Masuda1

  • 1Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.

PubMed

Insights

SUMOylation of DNA damage-binding protein 2 (DDB2) aids nucleotide excision repair (NER) by enhancing ubiquitination. This process is crucial for DNA repair and preventing genetic diseases.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Nucleotide excision repair (NER) is a critical DNA repair pathway. Defects in NER cause severe genetic disorders like xeroderma pigmentosum.
  • Damaged DNA-binding protein 2 (DDB2) is a key factor in DNA damage recognition within the NER pathway.
  • Previous studies showed DDB2 undergoes SUMOylation after UV irradiation, but its function remained unclear.

Purpose of the Study:

  • To investigate the physiological role of DDB2 SUMOylation in the NER pathway.
  • To identify the specific region and mechanism of DDB2 SUMOylation.

Main Methods:

  • Analysis of DDB2 mutants to pinpoint SUMOylation sites and functional motifs.
  • Investigating the impact of SUMOylation deficiency on DDB2 ubiquitination and chromatin retention.
  • Assessing the effect of DDB2 SUMOylation on the efficiency of the NER pathway.

Main Results:

  • The N-terminal tail of DDB2 is SUMOylated, facilitated by a SUMO-interacting motif (SIM) despite lacking a consensus SUMOylation sequence.
  • A DDB2 SIM mutant exhibited reduced ubiquitination and prolonged chromatin retention.
  • This SIM mutant displayed impaired NER, suggesting a role in lesion site handover to downstream factors like XPC.

Conclusions:

  • DDB2 SUMOylation is a crucial post-translational modification that enhances its ubiquitination.
  • This SUMOylation process facilitates efficient nucleotide excision repair by promoting timely protein dynamics at DNA damage sites.
  • Understanding DDB2 SUMOylation offers insights into NER pathway regulation and associated genetic diseases.

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