%0 Journal Article %J Proc Natl Acad Sci U S A %D 1997 %T An Arabidopsis photolyase mutant is hypersensitive to ultraviolet-B radiation. %A Landry, L G %A Stapleton, A E %A Lim, J %A Peter D Hoffman %A John B Hays %A Walbot, V %A Last, R L %K Apoenzymes %K Arabidopsis %K Deoxyribodipyrimidine Photo-Lyase %K DNA Repair %K Dose-Response Relationship, Radiation %K Fungal Proteins %K Membrane Glycoproteins %K Mutagenesis %K Mutation %K Pyrimidine Dimers %K Radiation Tolerance %K Ultraviolet Rays %X

Photolyases are DNA repair enzymes that use energy from blue light to repair pyrimidine dimers. We report the isolation of an Arabidopsis thaliana mutant (uvr2-1) that is defective in photorepair of cyclobutylpyrimidine dimers (CPDs). Whereas uvr2-1 is indistinguishable from wild type in the absence of UV light, low UV-B levels inhibit growth and cause leaf necrosis. uvr2-1 is more sensitive to UV-B than wild type when placed under white light after UV-B treatment. In contrast, recovery in darkness or in light lacking photoreactivating blue light results in equal injury in uvr2-1 and wild type. The uvr2-1 mutant is unable to remove CPDs in vivo, and plant extracts lack detectable photolyase activity. This recessive mutation segregates as a single gene located near the top of chromosome 1, and is a structural gene mutation in the type II CPD photolyase PHR1. This mutant provides evidence that CPD photolyase is required for plant survival in the presence of UV-B light.

%B Proc Natl Acad Sci U S A %V 94 %P 328-32 %8 1997 Jan 07 %G eng %N 1 %0 Journal Article %J Mol Gen Genet %D 1996 %T PHH1, a novel gene from Arabidopsis thaliana that encodes a protein similar to plant blue-light photoreceptors and microbial photolyases. %A Peter D Hoffman %A Batschauer, A %A John B Hays %K Amino Acid Sequence %K Apoenzymes %K Arabidopsis %K Arabidopsis Proteins %K Cryptochromes %K Deoxyribodipyrimidine Photo-Lyase %K DNA Repair %K DNA, Complementary %K Drosophila Proteins %K Escherichia coli %K Eye Proteins %K Flavoproteins %K Fungal Proteins %K Genes, Plant %K Genomic Library %K Introns %K Membrane Glycoproteins %K Molecular Sequence Data %K Photoreceptor Cells, Invertebrate %K Plant Proteins %K Plasmids %K Receptors, G-Protein-Coupled %K Saccharomyces cerevisiae %K Transformation, Genetic %K Ultraviolet Rays %X

A cDNA from Arabidopsis thaliana similar to microbial photolyase genes, and designated AT-PHH1, was isolated using a photolyase-like cDNA from Sinapsis alba (SA-PHR1) as a probe. Multiple isolations yielded only PHH1 cDNAs, and a few blue-light-receptor CRY1 (HY4) cDNAs (also similar to microbial photolyase genes), suggesting the absence of any other highly similar Arabidopsis genes. The AT-PHH1 and SA-PHR1 cDNA sequences predict 89% identity at the protein level, except for an AT-PHH1 C-terminal extension (111 amino acids), also not seen in microbial photolyases. AT-PHH1 and CRY1 show less similarity (54% p4erein identity), including respective C-terminal extensions that are themselves mostly dissimilar. Analysis of fifteen AT-PHH1 genomic isolates reveals a single gene, with three introns in the coding sequence and one in the 5'-untranslated leader. Full-length AT-PHH1, and both AT-PHH1 and AT-PHH1 delta C-513 (truncated to be approximately the size of microbial photolyase genes) cDNAs, were overexpressed, respectively, in yeast and Escherichia coli mutants hypersensitive to ultraviolet light. The absence of significant effects on resistance suggests either that any putative AT-PHH1 DNA repair activity requires cofactors/chromophores not present in yeast or E. coli, or that AT-PHH1 encodes a blue-light/ultraviolet-A receptor rather than a DNA repair protein.

%B Mol Gen Genet %V 253 %P 259-65 %8 1996 Nov 27 %G eng %N 1-2