Journal Article

AtPolλ, A Homolog of Mammalian DNA Polymerase λ in <i>Arabidopsis thaliana</i>, is Involved in the Repair of UV-B Induced DNA Damage Through the Dark Repair Pathway

Sujit Roy, Swarup Roy Choudhury, Sanjay Kumar Singh and Kali Pada Das

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 52, issue 2, pages 448-467
Published in print February 2011 | ISSN: 0032-0781
Published online January 2011 | e-ISSN: 1471-9053 | DOI: https://dx.doi.org/10.1093/pcp/pcr002
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

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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.

Keywords: AtPolλ; DNA damage; DNA polymerase; Nucleotide excision repair; UV-B

Journal Article.  12990 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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