<i>Trichoderma reesei</i> Rad51 tolerates mismatches in hybrid meiosis with diverse genome sequences.

Abstract

Most eukaryotes possess two RecA-like recombinases (ubiquitous Rad51 and meiosis-specific Dmc1) to promote interhomolog recombination during meiosis. However, some eukaryotes have lost Dmc1. Given that mammalian and yeast <i>Saccharomyces cerevisiae</i> (<i>Sc</i>) Dmc1 have been shown to stabilize recombination intermediates containing mismatches better than Rad51, we used the Pezizomycotina filamentous fungus <i>Trichoderma reesei</i> to address if and how Rad51-only eukaryotes conduct interhomolog recombination in zygotes with high sequence heterogeneity. We applied multidisciplinary approaches (next- and third-generation sequencing technology, genetics, cytology, bioinformatics, biochemistry, and single-molecule biophysics) to show that <i>T. reesei</i> Rad51 (<i>Tr</i>Rad51) is indispensable for interhomolog recombination during meiosis and, like <i>Sc</i>Dmc1, <i>Tr</i>Rad51 possesses better mismatch tolerance than <i>Sc</i>Rad51 during homologous recombination. Our results also indicate that the ancestral <i>Tr</i>Rad51 evolved to acquire <i>Sc</i>Dmc1-like properties by creating multiple structural variations, including via amino acid residues in the L1 and L2 DNA-binding loops.