title: Evolution of an MCM complex in flies that promotes meiotic crossovers by blocking BLM helicase.
abstract: Generation of meiotic crossovers in many eukaryotes requires the elimination of anti-crossover activities by using 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 minichromosome maintenance (MCM) proteins that functionally replace Msh4-Msh5. We found that 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 were reduced in Drosophila rec, mei-217, and mei-218 mutants; however, removal of the Bloom syndrome helicase (BLM) ortholog restored crossovers. Thus, MCMs were co-opted into a novel complex that replaced the meiotic pro-crossover function of Msh4-Msh5 in flies.
authors.affiliation: Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: Kathryn P
authors.initials: KP
authors.lastname: Kohl
authors.forename: Corbin D
authors.initials: CD
authors.lastname: Jones
authors.forename: Jeff
authors.initials: J
authors.lastname: Sekelsky
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000145:classification / Q000378:metabolism; D003434:Crossing Over, Genetic; D004265:DNA Helicases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins / Q000145:classification / Q000378:metabolism*; D019143:Evolution, Molecular; D008540:Meiosis; D010802:Phylogeny; D012641:Selection, Genetic; D014370:Tsetse Flies / Q000235:genetics*
chemical_list: D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; C489426:Mcm5 protein, Drosophila; C490723:REC protein, Drosophila; C103176:mei-218 protein, Drosophila; D004265:DNA Helicases; C470639:blm protein, Drosophila