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bioRxiv · 10.1101/2022.12.16.520760

Evolutionary conservation of the structure and function of meiotic Rec114-Mei4 and Mer2 complexes

Daccache, D.·Liloku, P.·De Jonge, E.·Volkov, A. N.·Claeys Bouuaert, C.
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Abstract

Meiosis-specific Rec114-Mei4 and Mer2 complexes are thought to enable Spo11-mediated DNA double-strand-break (DSB) formation through a mechanism that involves DNA-dependent condensation. However, the structure, molecular properties, and evolutionary conservation of Rec114-Mei4 and Mer2 are unclear. Here, we present AlphaFold structures of Rec114-Mei4 and Mer2 complexes, supported by nuclear magnetic resonance (NMR) spectroscopy, small-angle X-ray scattering (SAXS), and mutagenesis. We show that dimers composed of the Rec114 C-terminus form -helical chains that cup an N-terminal Mei4 -helix, and that Mer2 forms a parallel homotetrameric coiled coil. Both Rec114-Mei4 and Mer2 bind preferentially to branched DNA substrates, indicative of multivalent protein-DNA interactions. Indeed, the Rec114-Mei4 interaction domain contains two DNA-binding sites that point in opposite directions and drive condensation. The Mer2 coiled-coil domain bridges co-aligned DNA duplexes, likely through extensive electrostatic interactions along the length of the coiled coil. Finally, we show that the structure of Rec114-Mei4 and Mer2 are conserved across eukaryotes, while DNA-binding properties vary significantly. This work provides insights into the mechanism whereby Rec114-Mei4 and Mer2 complexes promote the assembly of the meiotic DSB machinery, and suggests a model where Mer2 condensation is the essential driver of assembly, with the DNA-binding activity of Rec114-Mei4 playing a supportive role.

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Daccache, D., Liloku, P., De Jonge, E., Volkov, A. N., Claeys Bouuaert, C.. 2022-12-17. Evolutionary conservation of the structure and function of meiotic Rec114-Mei4 and Mer2 complexes. https://doi.org/10.1101/2022.12.16.520760

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