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.
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.
Zhang
Caiguo
C
Institute of Cell Biology, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
Guo
Huiping
H
Zhang
Jun
J
Guo
Guangqin
G
Schumaker
Karen S
KS
Guo
Yan
Y
D029681:Arabidopsis Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D044842:Cullin Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020798:Two-Hybrid System Techniques; D014466:Ultraviolet Rays
D029681:Arabidopsis Proteins; C514806:CULLIN4 protein, Arabidopsis; D044842:Cullin Proteins