The role of conserved amino acid residues of Sae3 in Mei5-Sae3 complex for Dmc1 assembly in meiotic recombination

Meiotic recombination between homologous chromosomes is promoted by the collaborative action of two RecA homologs, Rad51 and meiosis-specific Dmc1. The filament assembly of Dmc1 is promoted by meiosis-specific Mei5-Sae3 in budding yeast. Mei5-Sae3 shows sequence similarity to fission yeast Sfr1-Swi5, which stimulates DNA strand exchanges by Rad51 as well as Dmc1. Sae3 and Swi5 share a conserved motif with the amino acid sequence YNEI/LK/RD. In this study, we analyzed the role of the YNEL residues in the Sae3 sequence in meiotic recombination and found that these residues are critical for Sae3 function in Dmc1 assembly. L59 substitution in the Sae3 protein disrupts complex formation with Mei5, while Y56 and N57 substitutions do not. These observations reveal the differential contribution of conserved YNEL residues to Sae3 activities in meiotic recombination.

Automated summary

In budding yeast, the meiosis-specific protein Mei5-Sae3 promotes the assembly of Dmc1 filaments by stimulating DNA strand exchanges by Rad51 and Dmc1. The YNEL residues in the Sae3 sequence play a critical role in Dmc1 assembly.