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

Abstract

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.

Post-translational cleavage of Mei5 of Dmc1 mediator, Mei5-Sae3 complex, in yeast meiosis

“…Given that the mei5-K95L mutant slightly decreased the spore viability to 91.7% compared to the control (97.8%), K95 is not essential for Mei5 function in vivo . A non-essential role of the highly-conserved residue(s) is also seen in Y56 and N57 of the conserved YNEL sequence of the Mei5 partner, Sae3 (Sawant et al, 2023).…”

“…To know the interaction of the Mei5-R97L protein with Sae3, we introduced the SAE3-Flag allele, which is functional (Hayase et al, 2004; Sawant et al, 2023), in the mei5-K95L and mei5-R97L mutants. Like the mei5-R97L , mei5-R97L SAE3-FLAG cells, which expressed both Mei5 and Sae3 protein as seen in the wild-type (Supplementary Figure S3A) were arrested at meiosis I and accumulated Rad51 and Rfa2 foci (Figure 3C, Supplementary Figure S3B).…”

“…The structural analysis suggests that the fission yeast Sfr1-Swi5 bind to a groove of Rad51 filament (Kuwabara et al, 2012). Although we analyzed the role of conserved resides of Sae3 in the yeast meiosis (Sawant et al, 2023), the contribution of conserved amino acids in Mei5 has not been analyzed. Here, we characterized the substitution of basic amino acids on putative conserved α-helixes of Mei5 protein and identified key residues for in vivo Mei5 function.…”

Mutational analysis of Mei5, a subunit of Mei5‐Sae3 complex, in Dmc1‐mediated recombination during yeast meiosis

“…Given that the mei5-K95L mutant slightly decreased the spore viability to 91.7% compared to the control (97.8%), Lys95 is not essential for Mei5 function in vivo. A non-essential role of the highly-conserved residue(s) is also seen in Tyr56 of the conserved YNEL sequence of the Mei5 partner, Sae3 (Sawant et al, 2023).…”

“…To know the interaction of the Mei5-R97L protein with Sae3, we introduced the SAE3-Flag allele, which is functional (Hayase et al, 2004;Sawant et al, 2023), in the mei5-K95L and mei5-R97L mutants. Like the mei5-R97L, mei5-R97L SAE3-FLAG cells, which expressed both Mei5 and Sae3 protein as seen in the wild-type (Supporting Information S1: Figure S3a) were arrested at meiosis I and accumulated Rad51 and Rfa2 foci (Figure 3a,c and Supporting Information S1: Figure S3b).…”