Cryo-EM structures of the Spo11 core complex bound to DNA

Area of Science:

• Molecular Biology
• Structural Biology
• Genetics

Background:

• Meiotic recombination initiates through DNA double-strand breaks (DSBs) generated by the topoisomerase-related enzyme Spo11.
• Conserved auxiliary factors support Spo11 function in DSB formation.
• High-resolution structural data of Spo11-DNA complexes have been lacking, limiting understanding of their architecture and DNA interaction.

Purpose of the Study:

• To determine the high-resolution structures of DNA-bound Spo11 core complexes.
• To elucidate the molecular mechanisms underlying DNA end-binding specificity and cleavage preferences of Spo11.
• To investigate the role of auxiliary factors and metal ions in Spo11 function.

Main Methods:

• Cryo-electron microscopy (cryo-EM) was employed to obtain structures of Saccharomyces cerevisiae Spo11 core complexes with Rec102, Rec104, and Ski8 bound to DNA.
• Structures were resolved up to 3.3-Å resolution.
• Functional data in yeast were used to support structural findings.

Main Results:

• High-resolution cryo-EM structures revealed monomeric core complexes of Spo11 bound extensively to the DNA backbone.
• The structures detailed interactions with the recessed 3'-OH and the first 5' overhanging nucleotide, defining DNA end-binding specificity.
• Insights into metal ion roles in DNA binding and structural variations in Top6BL homologs were uncovered.

Conclusions:

• The determined structures provide unprecedented molecular details of Spo11-DNA interactions, explaining DNA end recognition.
• These findings offer crucial insights into the in vivo DNA cleavage preferences of Spo11.
• The study reveals conserved and variable features of Spo11 complex architecture, advancing our understanding of meiotic DSB formation.