UVH1 is essential for dual incision during Arabidopsis nucleotide excision repair

Abstract

Plants rely on nucleotide excision repair to eliminate UV-induced pyrimidine dimers, which disrupt transcription and replication, thereby supporting growth and development under UV stress. In this process, endonucleases, the XPF-ERCC1 complex, and XPG in mammals make dual incisions around the damage site. In Arabidopsis thaliana, the XPF homolog UVH1 has been associated with several DNA repair pathways, but direct evidence for its role in the cleavage of damaged oligonucleotides during nucleotide excision repair has been limited. Materials and Methods: An excision assay was performed on UV-treated wild-type and uvh1 mutant Arabidopsis plants to examine the nucleotide excision repair activity. Phylogenetic analysis of XPF homologs was conducted across plant and other eukaryotic lineages. UVH1 transcript levels were analyzed in different developmental stages, tissue types, and stress conditions. Results: UVH1 is required for the excision of UV-induced pyrimidine dimers, which directly supports its role in the dual incision step of plant nucleotide excision repair. Phylogenetic analysis revealed that plant XPF homologs form a distinct, evolutionarily conserved lineage. UVH1 expression is regulated in a tissueand development-specific manner, responding dynamically to environmental stresses. Conclusion: This study provides direct evidence that UVH1 mediates dual incision during nucleotide excision repair in Arabidopsis, confirming its functional conservation with the animal XPF protein.