Coordinated actions of SLX1-SLX4 and MUS81-EME1 for Holliday junction resolution in human cells

Mol Cell. 2013 Oct 24;52(2):234-47. doi: 10.1016/j.molcel.2013.08.035. Epub 2013 Sep 26.


Holliday junctions (HJs) are four-way DNA intermediates that form during homologous recombination, and their efficient resolution is essential for chromosome segregation. Here, we show that three structure-selective endonucleases, namely SLX1-SLX4, MUS81-EME1, and GEN1, define two pathways of HJ resolution in human cells. One pathway is mediated by GEN1, whereas SLX1-SLX4 and MUS81-EME1 provide a second and genetically distinct pathway (SLX-MUS). Cells depleted for SLX-MUS or GEN1 pathway proteins exhibit severe defects in chromosome segregation and reduced survival. In response to CDK-mediated phosphorylation, SLX1-SLX4 and MUS81-EME1 associate at the G2/M transition to form a stable SLX-MUS holoenzyme, which can be reconstituted in vitro. Biochemical studies show that SLX-MUS is a HJ resolvase that coordinates the active sites of two distinct endonucleases during HJ resolution. This cleavage reaction is more efficient and orchestrated than that mediated by SLX1-SLX4 alone, which exhibits a potent nickase activity that acts promiscuously upon DNA secondary structures.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Cell Line, Transformed
  • DNA Repair
  • DNA, Cruciform*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Endodeoxyribonucleases / genetics
  • Endodeoxyribonucleases / metabolism*
  • Endonucleases / genetics
  • Endonucleases / metabolism*
  • Flow Cytometry
  • G2 Phase Cell Cycle Checkpoints / genetics
  • HeLa Cells
  • Holliday Junction Resolvases / genetics
  • Holliday Junction Resolvases / metabolism
  • Humans
  • Immunoblotting
  • Models, Genetic
  • Oligonucleotides / genetics
  • Oligonucleotides / metabolism
  • Protein Binding
  • RNA Interference
  • Recombinases / genetics
  • Recombinases / metabolism*
  • Sister Chromatid Exchange
  • Substrate Specificity


  • DNA, Cruciform
  • DNA-Binding Proteins
  • Oligonucleotides
  • Recombinases
  • Eme1 protein, human
  • Endodeoxyribonucleases
  • Endonucleases
  • MUS81 protein, human
  • SLX1 protein, human
  • SLX4 protein, human
  • GEN1 protein, human
  • Holliday Junction Resolvases