title: Oxidative DNA damage bypass in Arabidopsis thaliana requires DNA polymerase λ and proliferating cell nuclear antigen 2.
abstract: The oxidized base 7,8-oxoguanine (8-oxo-G) is the most common DNA lesion generated by reactive oxygen species. This lesion is highly mutagenic due to the frequent misincorporation of A opposite 8-oxo-G during DNA replication. In mammalian cells, the DNA polymerase (pol) family X enzyme DNA pol λ catalyzes the correct incorporation of C opposite 8-oxo-G, together with the auxiliary factor proliferating cell nuclear antigen (PCNA). Here, we show that Arabidopsis thaliana DNA pol λ, the only member of the X family in plants, is as efficient in performing error-free translesion synthesis past 8-oxo-G as its mammalian homolog. Arabidopsis, in contrast with animal cells, possesses two genes for PCNA. Using in vitro and in vivo approaches, we observed that PCNA2, but not PCNA1, physically interacts with DNA pol λ, enhancing its fidelity and efficiency in translesion synthesis. The levels of DNA pol λ in transgenic plantlets characterized by overexpression or silencing of Arabidopsis POLL correlate with the ability of cell extracts to perform error-free translesion synthesis. The important role of DNA pol λ is corroborated by the observation that the promoter of POLL is activated by UV and that both overexpressing and silenced plants show altered growth phenotypes.
authors.affiliation: Institute of Molecular Genetics, National Research Council, 27100 Pavia, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Amoroso
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Concia
authors.forename: Caterina
authors.initials: C
authors.lastname: Maggio
authors.forename: Cécile
authors.initials: C
authors.lastname: Raynaud
authors.forename: Catherine
authors.initials: C
authors.lastname: Bergounioux
authors.forename: Emmanuele
authors.initials: E
authors.lastname: Crespan
authors.forename: Rino
authors.initials: R
authors.lastname: Cella
authors.forename: Giovanni
authors.initials: G
authors.lastname: Maga
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D003001:Cloning, Molecular; D004249:DNA Damage; D019951:DNA Polymerase beta / Q000378:metabolism*; D018744:DNA, Plant / Q000378:metabolism; D006147:Guanine / Q000031:analogs & derivatives / Q000737:chemistry; D006801:Humans; D018384:Oxidative Stress; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D011523:Protoplasts / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; D018809:Proliferating Cell Nuclear Antigen; C024829:8-hydroxyguanine; D006147:Guanine; C415367:DNA polymerase beta2; D019951:DNA Polymerase beta