Crystal structure of the human MUS81-EME2 complex

Area of Science:

• Molecular biology
• Structural biology
• Biochemistry

Background:

• MUS81 is a crucial structure-specific endonuclease involved in DNA repair.
• In humans, MUS81 forms complexes with EME1 and EME2, with distinct roles in cell cycle phases.
• The structure of MUS81-EME1 is known, but MUS81-EME2 remains uncharacterized.

Purpose of the Study:

• To determine the crystal structure of the human MUS81-EME2 complex.
• To compare the biochemical activities and substrate recognition of MUS81-EME1 and MUS81-EME2 complexes.
• To elucidate the structural basis for DNA substrate recognition by MUS81-EME endonucleases.

Main Methods:

• X-ray crystallography to determine the MUS81-EME2 structure.
• Biochemical assays to assess endonuclease activity and substrate specificity.
• Structure-guided mutagenesis to investigate DNA binding interactions.

Main Results:

• The crystal structure of MUS81-EME2 was solved, showing a fold similar to MUS81-EME1.
• In vitro biochemical assays demonstrated identical substrate recognition and endonuclease activities for both MUS81-EME1 and MUS81-EME2 complexes.
• Structure-guided mutagenesis provided insights into the molecular mechanisms of DNA substrate binding.

Conclusions:

• The structural similarity and identical in vitro activities suggest that the distinct cellular functions of MUS81-EME1 and MUS81-EME2 complexes are likely regulated by temporal controls within the cell.
• This study provides a structural foundation for understanding how MUS81-EME endonucleases recognize diverse DNA structures.