Role of the AtRad1p endonuclease in homologous recombination in plants

Abstract

Using a specific recombination assay, we show in the plant Arabidopsis thaliana that AtRad1 protein plays a role in the removal of non-homologous tails in homologous recombination. Recombination in the presence of non-homologous overhangs is reduced 11-fold in the atrad1 mutant compared with the wild-type plants. AtRad1p is the A. thaliana homologue of the human Xpf and Saccharomyces cerevisiae Rad1 proteins. Rad1p is a subunit of the Rad1p/Rad10p structurespecific endonuclease that acts in nucleotide excision repair and inter-strand crosslink repair. This endonuclease also plays a role in mitotic recombination to remove non-homologous, 3′-ended overhangs from recombination intermediates. The Arabidopsis atrad1 mutant (uvh1), unlike rad1 mutants known from other eukaryotes, is hypersensitive to ionizing radiation. This last observation may indicate a more important role for the Rad1/Rad10 endonuclease in recombination in plants. This is the first direct demonstration of the involvement of AtRad1p in homologous recombination in plants.

The Structure-Specific Endonucleases MUS81 and SEND1 Are Essential for Telomere Stability in Arabidopsis

“…We thus examined the possibility that GEN1 and/or SEND1 might act redundantly with other nucleases for the resolution of recombination intermediates. We crossed our gen1 and send1 mutants with the previously characterized mus81 (Hartung et al, 2006) and xpf (Dubest et al, 2002) nuclease mutants. Knockout of SEND1 in plants lacking XPF showed a wild-type phenotype.…”

CENTRIN2 Modulates Homologous Recombination and Nucleotide Excision Repair in Arabidopsis[W]

“…However, this higher RAD1 transcipt level is not directly responsible for the reduced NER efficiency; it rather points to an activity in another step of the DNA repair process. On the other hand, a direct role for the Arabidopsis Rad1p endonuclease in HR has been recently shown; rad1 mutant plants exhibited a reduced level of removal of nonhomologous overhangs compared with wild-type plants (Dubest et al, 2002). Thus, the higher RAD1 mRNA steady state level in the centrin mutant may contribute to the higher HRF by an efficient removal of nonhomologous tails during the recombination process.…”

Re-engineering plant gene targeting

“…2). It might also be involved in the trimming of nonhomologous flanking ends [44]. Homologs of both ERCC1 and XPF have been identified in the Arabidopsis database (The Arabidopsis Genome Initiative, 2000), and mutants in both genes identified [33,45,46]; the mutants are gamma-sensitive, UV sensitive, and sensitive to the crosslinking agent mitomycin C. The role of UVH1 (the Arabidopsis XPF homolog) in nontargeted T-DNA integration has been investigated, with conflicting results [47][48][49].…”