title: AtPolλ, a homolog of mammalian DNA polymerase λ in Arabidopsis thaliana, is involved in the repair of UV-B induced DNA damage through the dark repair pathway.
abstract: Plants are constantly exposed to a wide range of environmental genotoxic stress factors including obligatory exposure to UV radiation in sunlight. Here, we report the functional characterization of a DNA repair protein, AtPolλ, a homolog of mammalian DNA polymerase λ in Arabidopsis, in relation to its role in repair of UV-B-induced DNA damage during early stages of seedling development. The abundance of the AtPolλ transcript and the protein levels were distinctly increased in response to UV-B irradiation in 6-day-old wild-type seedlings. Growth of atpolλ mutant seedlings, deficient in AtPolλ expression, was more sensitive to UV-B radiation compared with wild-type plants when seeds were exposed to UV-B radiation before germination. The atpolλ mutants showed accumulation of relatively higher amounts of DNA lesions than wild-type plants following UV-B exposure and were less proficient in repair of UV-induced DNA damage. Increased accumulation of AtPolλ protein in UV-B-irradiated 6-day-old wild-type seedlings during the dark recovery period has indicated a possible role for the protein in repair of UV-B-induced lesions in the dark. Overexpression of AtPolλ in the atpolλ mutant line partially complemented the repair proficiency of UV-B-induced DNA damage. In vitro repair synthesis assays using whole-cell extracts from the wild-type and atpolλ mutant line have further demonstrated the role of AtPolλ in repair synthesis of UV-B-damaged DNA in the dark through an excision repair mechanism. Overall, our results have indicated the possible involvement of AtPolλ in a plant's response for repair of UV-B-mediated DNA damage during seedling development.
authors.affiliation: Protein Chemistry Laboratory, Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700 009, West Bengal, India. sujitroy2006@gmail.com
authors.forename: Sujit
authors.initials: S
authors.lastname: Roy
authors.forename: Swarup Roy
authors.initials: SR
authors.lastname: Choudhury
authors.forename: Sanjay Kumar
authors.initials: SK
authors.lastname: Singh
authors.forename: Kali Pada
authors.initials: KP
authors.lastname: Das
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020552:Comet Assay; D004249:DNA Damage; D004260:DNA Repair; D018744:DNA, Plant / Q000528:radiation effects; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D009154:Mutation; D018749:RNA, Plant / Q000235:genetics; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; D018749:RNA, Plant; D004259:DNA-Directed DNA Polymerase