Arabidopsis UVH3 gene is a homolog of the Saccharomyces cerevisiae RAD2 and human XPG DNA repair genes.
To identify mechanisms of DNA repair in Arabidopsis thaliana, we have analyzed a mutant (uvh3) which exhibits increased sensitivity to ultraviolet (UV) light, H2O2 and ionizing radiation and displays a premature senescence phenotype. The uvh3 locus was mapped within chromosome III to the GL1 locus. A cosmid contig of the GL1 region was constructed, and individual cosmids were used to transform uvh3 mutant plants. Cosmid N9 was found to confer UV-resistance, H2O2-resistance and a normal senescence phenotype following transformation, indicating that the UVH3 gene is located on this cosmid and that all three phenotypes are due to the same mutation. Analysis of cosmid N9 sequences identified a gene showing strong similarity to two homologous repair genes, RAD2 (Saccharomyces cerevisiae) and XPG (human), which encode an endonuclease required for nucleotide excision repair of UV-damage. The uvh3 mutant was shown to carry a nonsense mutation in the coding region of the AtRAD2/XPG gene, thus revealing that the UVH3 gene encodes the AtRAD2/XPG gene product. In humans, the homologous XPG protein is also involved in removal of oxygen-damaged nucleotides by base excision repair. We discuss the possibility that the increased sensitivity of the uvh3 mutant to H2O2 and the premature senescence phenotype might result from failure to repair oxygen damage in plant tissues. Finally, we show that the AtRAD2/XPG gene is expressed at moderate levels in all plant tissues.
Liu
Z
Z
Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721, USA.
Hall
J D
JD
Mount
D W
DW
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins; D019757:Carbon-Oxygen Lyases / Q000235:genetics*; D002874:Chromosome Mapping; D004260:DNA Repair; D018076:DNA, Complementary; D018744:DNA, Plant; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D004268:DNA-Binding Proteins / Q000235:genetics*; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases; D004720:Endonucleases; D005656:Fungal Proteins / Q000235:genetics; D005816:Genetic Complementation Test; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors; D000099250:DNA Excision Repair Protein ERCC-5
D029681:Arabidopsis Proteins; D019757:Carbon-Oxygen Lyases; D018076:DNA, Complementary; D018744:DNA, Plant; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D004268:DNA-Binding Proteins; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases; D004720:Endonucleases; D005656:Fungal Proteins; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000099250:DNA Excision Repair Protein ERCC-5; C433744:UVH3 protein, Arabidopsis; C073998:RAD2 protein, S cerevisiae