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Chromosome Res. 2017 Oct;25(3-4):291-298. doi: 10.1007/s10577-017-9563-y. Epub 2017 Aug 12.

BIME2, a novel gene required for interhomolog meiotic recombination in the protist model organism Tetrahymena.

Author information

Department of Chromosome Biology, Vienna Biocenter, University of Vienna, 1030, Vienna, Austria.
Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, MD, 20892, USA.
Institute of Molecular Biotechnology of the Austrian Academy of Sciences and Research Institute of Molecular Pathology, 1030, Vienna, Austria.
Department of Chromosome Biology, Vienna Biocenter, University of Vienna, 1030, Vienna, Austria.


Meiotic recombination is initiated by DNA double-strand breaks (DSBs). Most DSBs are converted into nonreciprocal exchanges (gene conversions) or crossovers (COs) between sister chromatids. Only a minority of DSBs are processed toward interhomolog COs, the precursors of the chiasmata that connect homologous chromosomes. Dmc1, the meiosis-specific paralog of the universal recombination protein Rad51, is required for interhomolog COs; in its absence, univalents are primarily formed. Here, we report a ciliate-specific novel meiotic gene, BIME2, which also promotes interhomolog crossing over. In the bime2Δ mutant, DSBs are formed and repaired normally, but bivalent formation is strongly reduced. Bime2 protein forms foci on chromatin during meiotic prophase, and chromatin localization of Bime2 and Dmc1 is largely interdependent. Bime2 distantly resembles budding yeast Rdh54/Tid1 and the vertebrate Rad54B helicases and may have similar functions in promoting or stabilizing Dmc1 nucleoprotein filaments.


Chromosome pairing; Crossover; Double-strand break; Meiosis; Recombination

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