title: Structural and mechanistic insight into Holliday-junction dissolution by topoisomerase IIIα and RMI1.
abstract: Repair of DNA double-strand breaks via homologous recombination can produce double Holliday junctions (dHJs) that require enzymatic separation. Topoisomerase IIIα (TopIIIα) together with RMI1 disentangles the final hemicatenane intermediate obtained once dHJs have converged. How binding of RMI1 to TopIIIα influences it to behave as a hemicatenane dissolvase, rather than as an enzyme that relaxes DNA topology, is unknown. Here, we present the crystal structure of human TopIIIα complexed to the first oligonucleotide-binding domain (OB fold) of RMI1. TopIII assumes a toroidal type 1A topoisomerase fold. RMI1 attaches to the edge of the gate in TopIIIα through which DNA passes. RMI1 projects a 23-residue loop into the TopIIIα gate, thereby influencing the dynamics of its opening and closing. Our results provide a mechanistic rationale for how RMI1 stabilizes TopIIIα-gate opening to enable dissolution and illustrate how binding partners modulate topoisomerase function.
authors: Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
authors: Nicolas
authors: N
authors: Bocquet
authors: Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark.
authors: Anna H
authors: AH
authors: Bizard
authors: Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
authors: Wassim
authors: W
authors: Abdulrahman
authors: Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark.
authors: Nicolai B
authors: NB
authors: Larsen
authors: Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
authors: Mahamadou
authors: M
authors: Faty
authors: Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
authors: Simone
authors: S
authors: Cavadini
authors: Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
authors: Richard D
authors: RD
authors: Bunker
authors: Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California, USA.
authors: Stephen C
authors: SC
authors: Kowalczykowski
authors: 1] Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California, USA. [2].
authors: Petr
authors: P
authors: Cejka
authors: Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark.
authors: Ian D
authors: ID
authors: Hickson
authors: Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
authors: Nicolas H
authors: NH
authors: Thomä
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D053903:DNA Breaks, Double-Stranded; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D045566:DNA, Cruciform / Q000235:genetics*; D004277:DNA, Single-Stranded / Q000235:genetics; D004268:DNA-Binding Proteins; D017353:Gene Deletion; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D009841:Oligonucleotides / Q000737:chemistry / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012995:Solubility
chemical_list: D002352:Carrier Proteins; D045566:DNA, Cruciform; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D009841:Oligonucleotides; C501527:RMI1 protein, human; D029701:Saccharomyces cerevisiae Proteins; C502374:TOP3 protein, S cerevisiae; D004264:DNA Topoisomerases, Type I