title: Condensin II alleviates DNA damage and is essential for tolerance of boron overload stress in Arabidopsis.
abstract: Although excess boron (B) is known to negatively affect plant growth, its molecular mechanism of toxicity is unknown. We previously isolated two Arabidopsis thaliana mutants, hypersensitive to excess B (heb1-1 and heb2-1). In this study, we found that HEB1 and HEB2 encode the CAP-G2 and CAP-H2 subunits, respectively, of the condensin II protein complex, which functions in the maintenance of chromosome structure. Growth of Arabidopsis seedlings in medium containing excess B induced expression of condensin II subunit genes. Simultaneous treatment with zeocin, which induces DNA double-strand breaks (DSBs), and aphidicolin, which blocks DNA replication, mimicked the effect of excess B on root growth in the heb mutants. Both excess B and the heb mutations upregulated DSBs and DSB-inducible gene transcription, suggesting that DSBs are a cause of B toxicity and that condensin II reduces the incidence of DSBs. The Arabidopsis T-DNA insertion mutant atr-2, which is sensitive to replication-blocking reagents, was also sensitive to excess B. Taken together, these data suggest that the B toxicity mechanism in plants involves DSBs and possibly replication blocks and that plant condensin II plays a role in DNA damage repair or in protecting the genome from certain genotoxic stressors, particularly excess B.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Yayoi Tsujimoto
authors.initials: YT
authors.lastname: Inui
authors.forename: Shimpei
authors.initials: S
authors.lastname: Uraguchi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yoshizumi
authors.forename: Sachihiro
authors.initials: S
authors.lastname: Matsunaga
authors.forename: Minami
authors.initials: M
authors.lastname: Mastui
authors.forename: Masaaki
authors.initials: M
authors.lastname: Umeda
authors.forename: Kiichi
authors.initials: K
authors.lastname: Fukui
authors.forename: Toru
authors.initials: T
authors.lastname: Fujiwara
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001895:Boron / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002874:Chromosome Mapping; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D004261:DNA Replication; D018744:DNA, Plant / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018519:Meristem / Q000187:drug effects / Q000254:growth & development; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; C108312:condensin complexes; D000251:Adenosine Triphosphatases; D001895:Boron