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Meiotic recombination generates genetic diversity and promotes proper chromosomal segregation of parental chromosomes. This process requires a set of recombinases polymerized on single-stranded (ss) DNAs called the nucleoprotein filament to undergo homology search and strand exchange between homologous DNAs.

In Saccharomyces cerevisiae meiosis, programmed DNA double-strand breaks (DSBs) are formed by Spo11 to generate 3'-ssDNA tails. Once formed, ssDNA overhangs are rapidly bound by the abundant high-affinity ssDNA-binding protein, Replication protein A (RPA), to protect these ssDNAs from nucleolytic degradations or formation of the higher-order DNA structures.

RPA-coated ssDNA substrates are distinct from bare ssDNA substrates due to RPA's high affinity for ssDNA; therefore, the recombination mediator Mei5-Sae3 protein complex is required for the binding of recombinases onto RPA-coated ssDNA. However, the mechanistic role of Mei5-Sae3 in mediating Dmc1 activity remains unclear.

To investigate how Mei5-Sae3 stimulates Dmc1 to displace RPA and form nucleoprotein filaments, the research team, from NTU chemistry, NTU IBS, and Osaka University, utilized Biochemical protein purification techniques and single-molecule FRET and Colocalization Single-Molecule Spectroscopy (CoSMoS) techniques to capture the real-time binding of Dmc1 and dissociation of RPA on individual DNA with exceptional time resolution.

Their results are published in the journal Nucleic Acids Research.

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