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: Sujit Roy, Swarup Roy Choudhury, Dibyendu N Sengupta, Kali Pada Das
• Journal: Plant physiology (Plant Physiol) Vol. 162 Issue 2 Pg. 1195-210 (Jun 2013) ISSN: 1532-2548 [Electronic] United States
• PMID: 23660835 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Arabidopsis Proteins
• Cross-Linking Reagents
• DNA-Binding Proteins
• XRCC4 protein, Arabidopsis
• Mitomycin
• DNA polymerase beta2
• DNA Polymerase beta
• DNA polymerase lambda, Arabidopsis
• DNA-Directed DNA Polymerase
• DNA Ligases
• Lig4 protein, Arabidopsis

Topics

• Arabidopsis (drug effects, genetics, metabolism)
• Arabidopsis Proteins (genetics, metabolism)
• Cross-Linking Reagents (chemistry, pharmacology)
• DNA Breaks, Double-Stranded
• DNA Damage
• DNA End-Joining Repair
• DNA Ligases (genetics, metabolism)
• DNA Polymerase beta (genetics, metabolism)
• DNA Repair
• DNA-Binding Proteins (genetics, metabolism)
• DNA-Directed DNA Polymerase (genetics, metabolism)
• Gene Expression Regulation, Plant
• Genome, Plant
• Meristem (metabolism)
• Mitomycin (pharmacology)
• Mutation
• Plants, Genetically Modified
• Salinity
• Seedlings (drug effects, genetics, metabolism)