Structure guided functional analysis of the S. cerevisiae Mre11 complex

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• The Mre11 complex (Mre11, Rad50, Nbs1) is crucial for eukaryotic DNA damage response.
• It detects and repairs DNA double-strand breaks (DSBs) and activates signaling pathways.
• Mre11 and Rad50 are conserved core components, while Nbs1 is eukaryotic-specific.

Purpose of the Study:

• To determine the cryo-EM structure of the Saccharomyces cerevisiae Mre11-Rad50 complex bound to dsDNA.
• To investigate protein interfaces and DNA binding properties through mutational analysis.
• To understand the role of the Rad50 coiled-coil domain in ATP hydrolysis.

Main Methods:

• Cryo-electron microscopy (cryo-EM) at 3.2 Å resolution.
• Detailed mutational analyses of protein interfaces.
• Biochemical assays to assess DNA binding and ATP hydrolysis.

Main Results:

• A high-resolution cryo-EM structure of the Mre11-Rad50-dsDNA complex was obtained.
• Conserved residues critical for complex assembly and DNA binding were identified in Mre11 and Rad50.
• The Rad50 coiled-coil domain was shown to influence ATP hydrolysis over long distances.

Conclusions:

• The study provides structural insights into the Mre11-Rad50 complex's function in DNA repair.
• Identified key residues are essential for complex integrity and DNA interaction.
• Structural and functional data elucidate the mechanism of DNA damage signaling and repair.