title: Crossover/noncrossover differentiation, synaptonemal complex formation, and regulatory surveillance at the leptotene/zygotene transition of meiosis.
abstract: Yeast mutants lacking meiotic proteins Zip1, Zip2, Zip3, Mer3, and/or Msh5 (ZMMs) were analyzed for recombination, synaptonemal complex (SC), and meiotic progression. At 33 degrees C, recombination-initiating double-strand breaks (DSBs) and noncrossover products (NCRs) form normally while formation of single-end invasion strand exchange intermediates (SEIs), double Holliday junctions, crossover products (CRs), and SC are coordinately defective. Thus, during wild-type meiosis, recombinational interactions are differentiated into CR and NCR types very early, prior to onset of stable strand exchange and independent of SC. By implication, crossover interference does not require SC formation. We suggest that SC formation may require interference. Subsequently, CR-designated DSBs undergo a tightly coupled, ZMM-promoted transition that yields SEI-containing recombination complexes embedded in patches of SC. zmm mutant phenotypes differ strikingly at 33 degrees C and 23 degrees C, implicating higher temperature as a positive effector of recombination and identifying a checkpoint that monitors local CR-specific events, not SC formation, at late leptotene.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: G Valentin
authors.initials: GV
authors.lastname: Börner
authors.forename: Nancy
authors.initials: N
authors.lastname: Kleckner
authors.forename: Neil
authors.initials: N
authors.lastname: Hunter
mesh_terms: D020090:Chromosome Segregation / Q000235:genetics; D002875:Chromosomes / Q000235:genetics*; D045566:DNA, Cruciform / Q000235:genetics; D004277:DNA, Single-Stranded / Q000235:genetics; D018816:Genes, cdc / Q000502:physiology; D008540:Meiosis / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D011995:Recombination, Genetic / Q000235:genetics*; D012440:Saccharomyces / Q000235:genetics* / Q000378:metabolism; D013573:Synaptonemal Complex / Q000235:genetics*; D013696:Temperature
chemical_list: D045566:DNA, Cruciform; D004277:DNA, Single-Stranded