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Nat Chem Biol. 2019 Mar;15(3):269-275. doi: 10.1038/s41589-018-0209-y. Epub 2019 Jan 21.

Junction resolving enzymes use multivalency to keep the Holliday junction dynamic.

Author information

1
Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Champaign, IL, USA. ruobozhou@fas.harvard.edu.
2
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA. ruobozhou@fas.harvard.edu.
3
Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD, USA.
4
Cancer Research UK Nucleic Acid Structure Research Group, School of Life Sciences, The University of Dundee, Dundee, UK.
5
Department of Life Science, Pohang University of Science and Technology, Pohang, South Korea.
6
Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Champaign, IL, USA. tjha@jhu.edu.
7
Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD, USA. tjha@jhu.edu.
8
Howard Hughes Medical Institute, Baltimore, MD, USA. tjha@jhu.edu.
9
Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA. tjha@jhu.edu.
10
Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA. tjha@jhu.edu.

Abstract

Holliday junction (HJ) resolution by resolving enzymes is essential for chromosome segregation and recombination-mediated DNA repair. HJs undergo two types of structural dynamics that determine the outcome of recombination: conformer exchange between two isoforms and branch migration. However, it is unknown how the preferred branch point and conformer are achieved between enzyme binding and HJ resolution given the extensive binding interactions seen in static crystal structures. Single-molecule fluorescence resonance energy transfer analysis of resolving enzymes from bacteriophages (T7 endonuclease I), bacteria (RuvC), fungi (GEN1) and humans (hMus81-Eme1) showed that both types of HJ dynamics still occur after enzyme binding. These dimeric enzymes use their multivalent interactions to achieve this, going through a partially dissociated intermediate in which the HJ undergoes nearly unencumbered dynamics. This evolutionarily conserved property of HJ resolving enzymes provides previously unappreciated insight on how junction resolution, conformer exchange and branch migration may be coordinated.

PMID:
30664685
DOI:
10.1038/s41589-018-0209-y

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