A UVB-hypersensitive mutant in Arabidopsis thaliana is defective in the DNA damage response.
To investigate UVB DNA damage response in higher plants, we used a genetic screen to isolate Arabidopsis thaliana mutants that are hypersensitive to UVB irradiation, and isolated a UVB-sensitive mutant, termed suv2 (for sensitive to UV 2) that also displayed hypersensitivity to gamma-radiation and hydroxyurea. This phenotype is reminiscent of the Arabidopsis DNA damage-response mutant atr. The suv2 mutation was mapped to the bottom of chromosome 5, and contains an insertion in an unknown gene annotated as MRA19.1. RT-PCR analysis with specific primers to MRA19.1 detected a transcript consisting of 12 exons. The transcript is predicted to encode a 646 amino acid protein that contains a coiled-coil domain and two instances of predicted PIKK target sequences within the N-terminal region. Fusion proteins consisting of the predicted MRA19.1 and DNA-binding or activation domain of yeast transcription factor GAL4 interacted with each other in a yeast two-hybrid system, suggesting that the proteins form a homodimer. Expression of CYCB1;1:GUS gene, which encodes a labile cyclin:GUS fusion protein to monitor mitotic activity by GUS activity, was weaker in the suv2 plant after gamma-irradiation than in the wild-type plants and was similar to that in the atr plants, suggesting that the suv2 mutant is defective in cell-cycle arrest in response to DNA damage. Overall, these results suggest that the gene disrupted in the suv2 mutant encodes an Arabidopsis homologue of the ATR-interacting protein ATRIP.
Sakamoto
Ayako N
AN
Radiation-Applied Biology Division, Japan Atomic Energy Agency, Watanuki-machi 1233, Takasaki, Gumma 370-1292, Japan. sakamoto.ayako@jaea.go.jp
Lan
Vo Thi Thuong
VT
Puripunyavanich
Vichai
V
Hase
Yoshihiro
Y
Yokota
Yuichiro
Y
Shikazono
Naoya
N
Nakagawa
Mayu
M
Narumi
Issay
I
Tanaka
Atsushi
A
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D032461:Chromosomes, Plant; D004249:DNA Damage; D018744:DNA, Plant / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009154:Mutation; D055503:Protein Multimerization; D014466:Ultraviolet Rays
D029681:Arabidopsis Proteins; D018744:DNA, Plant