Arabidopsis DNA ligase IV is induced by γ‐irradiation and interacts with an Arabidopsis homologue of the double strand break repair protein XRCC4

• Published in: The Plant journal : for cell and molecular biology Vol. 24; no. 1; pp. 67 - 78
• Main Authors: West, Christopher E., Waterworth, Wanda M., Jiang, Qing, Bray, Clifford M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.10.2000; Blackwell Science
• Subjects: Amino Acid Sequence; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis - radiation effects; Arabidopsis thaliana; AtLIG4 gene; Biological and medical sciences; BRCT domain; DNA Ligase ATP; DNA ligase IV; DNA Ligases - biosynthesis; DNA Ligases - genetics; DNA Ligases - metabolism; DNA Repair; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; Dose-Response Relationship, Radiation; double-strand break repair; Enzyme Induction - radiation effects; Enzymes; Fundamental and applied biological sciences. Psychology; Gamma Rays; Gene Expression Regulation, Enzymologic - radiation effects; Gene Expression Regulation, Plant - radiation effects; Humans; Light; Metabolism; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Molecular Weight; Mutagenesis. Repair; non‐homologous end joining; Plant physiology and development; Recombination, Genetic; Saccharomyces cerevisiae - enzymology; Sequence Alignment; Sequence Homology, Amino Acid; Ultraviolet Rays; XRCC4 protein; Enzyme; Induction; DNA binding protein; DNA ligase (ATP); Phosphoric ester ligases; Arabidopsis thaliana; Characterization; Double stranded DNA; Gamma irradiation; Cruciferae; Ligases; Dicotyledones; Angiospermae; Spermatophyta; Experimental plant; Molecular cloning; Repair; Molecular domain
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313x.2000.00856.x

Summary Rejoining of single‐ and double‐strand breaks (DSBs) introduced in DNA during replication, recombination, and DNA damage is catalysed by DNA ligase enzymes. Eukaryotes possess multiple DNA ligase enzymes, each having distinct roles in cellular metabolism. Double‐strand breaks in DNA, which can occur spontaneously in the cell or be induced experimentally by γ‐irradiation, represent one of the most serious threats to genomic integrity. Non‐homologous end joining (NHEJ) rather than homologous recombination is the major pathway for repair of DSBs in organisms with complex genomes, including humans and plants. DNA ligase IV in Saccharomyces cerevisiae and humans catalyses the final step in the NHEJ pathway of DSB repair. In this study we identify an Arabidopsis thaliana homologue (AtLIG4) of human and S. cerevisiae DNA ligase IV which is shown to encode an ATP‐dependent DNA ligase with a theoretical molecular mass of 138 kDa and 48% similarity in amino‐acid sequence to the human DNA ligase IV. Yeast two‐hybrid analysis demonstrated a strong interaction between A. thaliana DNA ligase IV and the A. thaliana homologue of the human DNA ligase IV‐binding protein XRCC4. This interaction is shown to be mediated via the tandem BRCA C‐terminal domains of A. thaliana DNA ligase IV protein. Expression of AtLIG4 is induced by γ‐irradiation but not by UVB irradiation, consistent with an in vivo role for the A. thaliana DNA ligase IV in DSB repair.