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Detection of Protein Ubiquitination
09:00

Detection of Protein Ubiquitination

Published on: August 19, 2009

UV-induced ubiquitylation of XPC protein mediated by UV-DDB-ubiquitin ligase complex

Kaoru Sugasawa1, Yuki Okuda, Masafumi Saijo

  • 1Cellular Physiology Laboratory, RIKEN Discovery Research Institute, Japan Science and Technology Agency, Wako, Saitama 351-0198, Japan. sugasawa@riken.jp

Cell
|May 11, 2005
PubMed

Insights

Ubiquitylation of the xeroderma pigmentosum group C (XPC) protein complex is crucial for DNA repair. This process, dependent on UV-damaged DNA binding protein (UV-DDB), facilitates the transfer of UV-induced DNA damage for nucleotide excision repair (NER).

Area of Science:

  • Molecular Biology
  • DNA Repair Mechanisms
  • Cellular Response to UV Radiation

Background:

  • The xeroderma pigmentosum group C (XPC) complex is vital for recognizing genomic DNA damage during nucleotide excision repair (NER).
  • The ultraviolet light-damaged DNA binding protein (UV-DDB) complex is implicated in recognizing NER-inducing damage, but its exact role and relationship with XPC are unclear.

Purpose of the Study:

  • To investigate the role of ubiquitylation in the interaction between XPC and UV-DDB during DNA repair.
  • To elucidate the functional consequences of XPC ubiquitylation on DNA binding and lesion recognition.

Main Methods:

  • Studied UV irradiation effects on XPC protein in mammalian cells.
  • Investigated physical interactions between XPC and UV-DDB using biochemical assays.
  • Analyzed the impact of polyubiquitylation on DNA binding properties of XPC and UV-DDB.
  • Assessed the requirement of ubiquitylation for cell-free NER of UV-induced photoproducts.

Main Results:

  • XPC undergoes reversible ubiquitylation following UV irradiation, contingent on functional UV-DDB activity.
  • XPC and UV-DDB physically interact and are polyubiquitylated by a UV-DDB-associated ubiquitin ligase.
  • Polyubiquitylation modifies the DNA binding characteristics of both XPC and UV-DDB.
  • Ubiquitylation is essential for cell-free NER of UV-induced (6-4) photoproducts when UV-DDB is bound to the lesion.

Conclusions:

  • Ubiquitylation is a critical regulatory mechanism in the NER pathway.
  • The findings suggest ubiquitylation mediates the transfer of UV-damaged DNA lesions from UV-DDB to XPC.
  • This study clarifies the interplay between UV-DDB, XPC, and ubiquitylation in processing UV-induced DNA damage.

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