title: Involvement of AtPolλ in the repair of high salt- and DNA cross-linking agent-induced double strand breaks in Arabidopsis.
abstract: DNA polymerase λ (Pol λ) is the sole member of family X DNA polymerase in plants and plays a crucial role in nuclear DNA damage repair. Here, we report the transcriptional up-regulation of Arabidopsis (Arabidopsis thaliana) AtPolλ in response to abiotic and genotoxic stress, including salinity and the DNA cross-linking agent mitomycin C (MMC). The increased sensitivity of atpolλ knockout mutants toward high salinity and MMC treatments, with higher levels of accumulation of double strand breaks (DSBs) than wild-type plants and delayed repair of DSBs, has suggested the requirement of Pol λ in DSB repair in plants. AtPolλ overexpression moderately complemented the deficiency of DSB repair capacity in atpolλ mutants. Transcriptional up-regulation of major nonhomologous end joining (NHEJ) pathway genes KU80, X-RAY CROSS COMPLEMENTATION PROTEIN4 (XRCC4), and DNA Ligase4 (Lig4) along with AtPolλ in Arabidopsis seedlings, and the increased sensitivity of atpolλ-2/atxrcc4 and atpolλ-2/atlig4 double mutants toward high salinity and MMC treatments, indicated the involvement of NHEJ-mediated repair of salinity- and MMC-induced DSBs. The suppressed expression of NHEJ genes in atpolλ mutants suggested complex transcriptional regulation of NHEJ genes. Pol λ interacted directly with XRCC4 and Lig4 via its N-terminal breast cancer-associated C terminus (BRCT) domain in a yeast two-hybrid system, while increased sensitivity of BRCT-deficient Pol λ-expressing transgenic atpolλ-2 mutants toward genotoxins indicated the importance of the BRCT domain of AtPolλ in mediating the interactions for processing DSBs. Our findings provide evidence for the direct involvement of DNA Pol λ in the repair of DSBs in a plant genome.
authors: Protein Chemistry Laboratory, Department of Chemistry, Bose Institute, Kolkata 700 009, West Bengal, India. sujitroy2006@gmail.com
authors: Sujit
authors: S
authors: Roy
authors: Swarup Roy
authors: SR
authors: Choudhury
authors: Dibyendu N
authors: DN
authors: Sengupta
authors: Kali Pada
authors: KP
authors: Das
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000494:pharmacology; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D059766:DNA End-Joining Repair; D011088:DNA Ligases / Q000235:genetics / Q000378:metabolism; D019951:DNA Polymerase beta / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D018519:Meristem / Q000378:metabolism; D016685:Mitomycin / Q000494:pharmacology; D009154:Mutation; D030821:Plants, Genetically Modified; D054712:Salinity; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; C581740:XRCC4 protein, Arabidopsis; D016685:Mitomycin; C415367:DNA polymerase beta2; D019951:DNA Polymerase beta; C585937:DNA polymerase lambda, Arabidopsis; D004259:DNA-Directed DNA Polymerase; D011088:DNA Ligases; C525218:Lig4 protein, Arabidopsis
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