Functional organization of protein determinants of meiotic DNA break hotspots

• Published in: Scientific reports Vol. 7; no. 1; pp. 1393 - 13
• Main Authors: Ma, Lijuan, Fowler, Kyle R, Martín-Castellanos, Cristina, Smith, Gerald R
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group UK 03.05.2017; Nature Portfolio
• Subjects: Cell Cycle Proteins - genetics; Cell Cycle Proteins - isolation & purification; DNA Breaks, Double-Stranded; Gene Conversion; Introns; Meiosis; Mutation, Missense; Nuclear Proteins - genetics; Nuclear Proteins - isolation & purification; Schizosaccharomyces - genetics; Schizosaccharomyces pombe Proteins - genetics; Schizosaccharomyces pombe Proteins - isolation & purification
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-00742-3

During Schizosaccharomyces pombe meiotic prophase, homologous chromosomes are co-aligned by linear elements (LinEs) analogous to the axial elements of the synaptonemal complex (SC) in other organisms. LinE proteins also promote the formation of meiotic DNA double-strand breaks (DSBs), the precursors of cross-overs. Rec10 is required for essentially all DSBs and recombination, and three others (Rec25, Rec27, and Mug20) are protein determinants of DSB hotspots - they bind DSB hotspots with high specificity and are required for DSB formation there. These four LinE proteins co-localize in the nucleus in an interdependent way, suggesting they form a complex. We used random mutagenesis to uncover recombination-deficient missense mutants with novel properties. Some missense mutations changed essential residues conserved among Schizosaccharomyces species. DSB formation, gene conversion, and crossing-over were coordinately reduced in the mutants tested. Based on our mutant analysis, we revised the rec27 open reading frame: the new start codon is in the previously annotated first intron. Genetic and fluorescence-microscopy assays indicated that the Rec10 N- and C-terminal regions have complex interactions with Rec25. These mutants are a valuable resource to elucidate further how LinE proteins and the related SCs of other species regulate meiotic DSB formation to form crossovers crucial for meiosis.