Arabidopsis cockayne syndrome A-like proteins 1A and 1B form a complex with CULLIN4 and damage DNA binding protein 1A and regulate the response to UV irradiation

Plant Cell. 2010 Jul;22(7):2353-69. doi: 10.1105/tpc.110.073973. Epub 2010 Jul 9.


In plants, as in animals, DNA is constantly subject to chemical modification. UV-B irradiation is a major genotoxic agent and has significant effects on plant growth and development. Through forward genetic screening, we identified a UV-B-sensitive mutant (csaat1a-3) in Arabidopsis thaliana, in which expression of CSAat1A, encoding a Cockayne Syndrome A-like protein, is reduced due to insertion of a T-DNA in the promoter region. Arabidopsis lacking CSAat1A or its homolog CSAat1B is more sensitive to UV-B and the genotoxic drug methyl methanesulfonate and exhibits reduced transcription-coupled repair activity. Yeast two-hybrid analysis indicated that both CSAat1A and B interact with DDB1A (UV-Damage DNA Binding Protein1). Coimmunoprecipitation assays demonstrated that CSAat1A and B associate with the CULLIN4 (CUL4)-DDB1A complex in Arabidopsis. A split-yellow fluorescent protein assay showed that this interaction occurs in the nucleus, consistent with the idea that the CUL4-DDB1A-CSA complex functions as a nuclear E3 ubiquitin ligase. CSAat1A and B formed heterotetramers in Arabidopsis. Taken together, our data suggest that the plant CUL4-DDB1A(CSAat1A and B) complex represents a unique mechanism to promote ubiquitination of substrates in response to DNA damage.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis Proteins / metabolism*
  • Cell Nucleus / metabolism
  • Cullin Proteins / metabolism*
  • Promoter Regions, Genetic
  • Protein Binding
  • Two-Hybrid System Techniques
  • Ultraviolet Rays*


  • Arabidopsis Proteins
  • CULLIN4 protein, Arabidopsis
  • Cullin Proteins

Associated data

  • RefSeq/NM_101831
  • RefSeq/NM_102549
  • RefSeq/NM_116781
  • RefSeq/NM_123990