title: GMI1, a structural-maintenance-of-chromosomes-hinge domain-containing protein, is involved in somatic homologous recombination in Arabidopsis.
abstract: DNA double-strand breaks (DSBs) pose one of the most severe threats to genome integrity, potentially leading to cell death. After detection of a DSB, the DNA damage and repair response is initiated and the DSB is repaired by non-homologous end joining and/or homologous recombination. Many components of these processes are still unknown in Arabidopsis thaliana. In this work, we characterized γ-irradiation and mitomycin C induced 1 (GMI1), a member of the SMC-hinge domain-containing protein family. RT-PCR analysis and promoter-GUS fusion studies showed that γ-irradiation, the radio-mimetic drug bleocin, and the DNA cross-linking agent mitomycin C strongly enhance GMI1 expression particularly in meristematic tissues. The induction of GMI1 by γ-irradiation depends on the signalling kinase Ataxia telangiectasia-mutated (ATM) but not on ATM and Rad3-related (ATR). Epistasis analysis of single and double mutants demonstrated that ATM acts upstream of GMI1 while the atr gmi1-2 double mutant was more sensitive than the respective single mutants. Comet assay revealed a reduced rate of DNA double-strand break repair in gmi1 mutants during the early recovery phase after exposure to bleocin. Moreover, the rate of homologous recombination of a reporter construct was strongly reduced in gmi1 mutant plants upon exposure to bleocin or mitomycin C. GMI1 is the first member of its protein family known to be involved in DNA repair.
authors.affiliation: Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Dr. Bohr-Gasse 3, 1030 Vienna, Austria. gudrun.boehmdorfer@gmi.oeaw.ac.at
authors.forename: Gudrun
authors.initials: G
authors.lastname: Böhmdorfer
authors.forename: Alexander
authors.initials: A
authors.lastname: Schleiffer
authors.forename: Reinhard
authors.initials: R
authors.lastname: Brunmeir
authors.forename: Stefan
authors.initials: S
authors.lastname: Ferscha
authors.forename: Viktoria
authors.initials: V
authors.lastname: Nizhynska
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Kozák
authors.forename: Karel J
authors.initials: KJ
authors.lastname: Angelis
authors.forename: David P
authors.initials: DP
authors.lastname: Kreil
authors.forename: Dieter
authors.initials: D
authors.lastname: Schweizer
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D032461:Chromosomes, Plant / Q000378:metabolism*; D003001:Cloning, Molecular; D020552:Comet Assay; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant; D050939:Gene Fusion; D018519:Meristem / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D046228:Microarray Analysis; D016685:Mitomycin / Q000494:pharmacology; D016254:Mutagenesis, Insertional; D011995:Recombination, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D036226:Seedlings / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D018744:DNA, Plant; C036483:T-DNA; D016685:Mitomycin