title: Functional interactions of Rec24, the fission yeast ortholog of mouse Mei4, with the meiotic recombination-initiation complex.
abstract: A physical connection between each pair of homologous chromosomes is crucial for reductional chromosome segregation during the first meiotic division and therefore for successful meiosis. Connection is provided by recombination (crossing over) initiated by programmed DNA double-strand breaks (DSBs). Although the topoisomerase-like protein Spo11 makes DSBs and is evolutionarily conserved, how Spo11 (Rec12 in fission yeast) is regulated to form DSBs at the proper time and place is poorly understood. Several additional (accessory) proteins for DSB formation have been inferred in different species from yeast to mice. Here, we show that Rec24 is a bona fide accessory protein in Schizosaccharomyces pombe. Rec24 is required genome-wide for crossing-over and is recruited to meiotic chromosomes during prophase in a Rec12-independent manner forming foci on linear elements (LinEs), structurally related to the synaptonemal complex of other eukaryotes. Stabilization of Rec24 on LinEs depends on another accessory protein, Rec7, with which Rec24 forms complexes in vivo. We propose that Rec24 marks LinE-associated recombination sites, that stabilization of its binding by Rec7 facilitates the loading or activation of Rec12, and that only stabilized complexes containing Rec24 and Rec7 promote DSB formation. Based on the recent report of Rec24 and Rec7 conservation, interaction between Rec24 and Rec7 might be widely conserved in DSB formation.
authors.affiliation: Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Bonfils
authors.forename: Ana E
authors.initials: AE
authors.lastname: Rozalén
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Smith
authors.forename: Sergio
authors.initials: S
authors.lastname: Moreno
authors.forename: Cristina
authors.initials: C
authors.lastname: Martín-Castellanos
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D003434:Crossing Over, Genetic; D053903:DNA Breaks, Double-Stranded; D008540:Meiosis; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding; D011995:Recombination, Genetic; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics* / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D013573:Synaptonemal Complex / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C560744:Rec24 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; C077080:rec7 protein, S pombe; C523697:Ccnb1ip1 protein, mouse; D044767:Ubiquitin-Protein Ligases