Evolution of a MCM complex in flies promoting meiotic crossovers by blocking BLM helicase

Generation of meiotic crossovers in many eukaryotes requires the elimination of anti-crossover activities by utilizing the Msh4–Msh5 heterodimer to block helicases. Msh4 and Msh5 have been lost from the flies Drosophila and Glossina but we identified a complex of mini-chromosome maintenance (MCM) pr...

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Published inScience (American Association for the Advancement of Science) Vol. 338; no. 6112; pp. 1363 - 1365
Main Authors Kohl, Kathryn P., Jones, Corbin D., Sekelsky, Jeff
Format Journal Article
LanguageEnglish
Published 07.12.2012
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Summary:Generation of meiotic crossovers in many eukaryotes requires the elimination of anti-crossover activities by utilizing the Msh4–Msh5 heterodimer to block helicases. Msh4 and Msh5 have been lost from the flies Drosophila and Glossina but we identified a complex of mini-chromosome maintenance (MCM) proteins that functionally replace Msh4–Msh5. REC, an ortholog of MCM8 that evolved under strong positive selection in flies, interacts with MEI-217 and MEI-218, which arose from a previously undescribed metazoan-specific MCM protein. Meiotic crossovers are reduced in Drosophila rec , mei-217 , and mei-218 mutants; however, removal of the Bloom syndrome helicase ortholog restores crossovers. Thus, MCMs were co-opted into a novel complex that replaces the meiotic pro-crossover function of Msh4–Msh5 in flies.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1228190