title: The RTR Complex Partner RMI2 and the DNA Helicase RTEL1 Are Both Independently Involved in Preserving the Stability of 45S rDNA Repeats in Arabidopsis thaliana.
abstract: The stability of repetitive sequences in complex eukaryotic genomes is safeguarded by factors suppressing homologues recombination. Prominent in this is the role of the RTR complex. In plants, it consists of the RecQ helicase RECQ4A, the topoisomerase TOP3α and RMI1. Like mammals, but not yeast, plants harbor an additional complex partner, RMI2. Here, we demonstrate that, in Arabidopsis thaliana, RMI2 is involved in the repair of aberrant replication intermediates in root meristems as well as in intrastrand crosslink repair. In both instances, RMI2 is involved independently of the DNA helicase RTEL1. Surprisingly, simultaneous loss of RMI2 and RTEL1 leads to loss of male fertility. As both the RTR complex and RTEL1 are involved in suppression of homologous recombination (HR), we tested the efficiency of HR in the double mutant rmi2-2 rtel1-1 and found a synergistic enhancement (80-fold). Searching for natural target sequences we found that RTEL1 is required for stabilizing 45S rDNA repeats. In the double mutant with rmi2-2 the number of 45S rDNA repeats is further decreased sustaining independent roles of both factors in this process. Thus, loss of suppression of HR does not only lead to a destabilization of rDNA repeats but might be especially deleterious for tissues undergoing multiple cell divisions such as the male germline.
authors.affiliation: Botanical Institute II, Karlsruhe Institute of Technology, Karlsruhe, Germany.
authors.forename: Sarah
authors.identifier: http://orcid.org/0000-0002-7558-478X
authors.initials: S
authors.lastname: Röhrig
authors.affiliation: Botanical Institute II, Karlsruhe Institute of Technology, Karlsruhe, Germany.
authors.forename: Susan
authors.identifier: http://orcid.org/0000-0003-3249-2161
authors.initials: S
authors.lastname: Schröpfer
authors.affiliation: Botanical Institute II, Karlsruhe Institute of Technology, Karlsruhe, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Knoll
authors.affiliation: Botanical Institute II, Karlsruhe Institute of Technology, Karlsruhe, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Puchta
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics*; D004265:DNA Helicases / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics*; D004264:DNA Topoisomerases, Type I / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D059765:Homologous Recombination / Q000235:genetics*; D018519:Meristem / Q000235:genetics / Q000254:growth & development; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development; D011058:Pollen / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D002868:Chromosomal Proteins, Non-Histone; D004275:DNA, Ribosomal; C534772:RMI1 protein, Arabidopsis; C000618217:RMI2 protein, Arabidopsis; D012335:RNA, Ribosomal; C088179:RNA, ribosomal, 45S; D004265:DNA Helicases; C000602077:RTEL1 protein, Arabidopsis; C514439:RecQ4A protein, Arabidopsis; D004264:DNA Topoisomerases, Type I