Crystal structures of the structure‐selective nuclease Mus81‐Eme1 bound to flap DNA substrates |
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Authors: | Gwang Hyeon Gwon Aera Jo Kyuwon Baek Kyeong Sik Jin Yaoyao Fu Jong‐Bong Lee YoungChang Kim Yunje Cho |
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Institution: | 1. Department of Life Science, Pohang University of Science and Technology, Pohang, South Korea;2. Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, South Korea;3. Department of Physics, Pohang University of Science and Technology, Pohang, South Korea;4. Biosciences Division, Structural Biology Center, Argonne National Laboratory, Argonne, IL, USA |
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Abstract: | The Mus81‐Eme1 complex is a structure‐selective endonuclease with a critical role in the resolution of recombination intermediates during DNA repair after interstrand cross‐links, replication fork collapse, or double‐strand breaks. To explain the molecular basis of 3′ flap substrate recognition and cleavage mechanism by Mus81‐Eme1, we determined crystal structures of human Mus81‐Eme1 bound to various flap DNA substrates. Mus81‐Eme1 undergoes gross substrate‐induced conformational changes that reveal two key features: (i) a hydrophobic wedge of Mus81 that separates pre‐ and post‐nick duplex DNA and (ii) a “5′ end binding pocket” that hosts the 5′ nicked end of post‐nick DNA. These features are crucial for comprehensive protein‐DNA interaction, sharp bending of the 3′ flap DNA substrate, and incision strand placement at the active site. While Mus81‐Eme1 unexpectedly shares several common features with members of the 5′ flap nuclease family, the combined structural, biochemical, and biophysical analyses explain why Mus81‐Eme1 preferentially cleaves 3′ flap DNA substrates with 5′ nicked ends. |
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Keywords: | crystal structure flap DNA homologous recombination interstrand cross‐link repair Mus81 |
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