title: A Zip3-like protein plays a role in crossover formation in the SC-less meiosis of the protistTetrahymena.
abstract: When programmed meiotic DNA double-strand breaks (DSBs) undergo recombinational repair, genetic crossovers (COs) may be formed. A certain level of this is required for the faithful segregation of chromosomes, but the majority of DSBs are processed toward a safer alternative, namely noncrossovers (NCOs), via nonreciprocal DNA exchange. At the crossroads between these two DSB fates is the Msh4-Msh5 (MutSγ) complex, which stabilizes CO-destined recombination intermediates and members of the Zip3/RNF212 family of RING finger proteins, which in turn stabilize MutSγ. These proteins function in the context of the synaptonemal complex (SC) and mainly act on SC-dependent COs. Here we show that in the SC-less ciliateTetrahymena, Zhp3 (a protein distantly related to Zip3/RNF212), together with MutSγ, is responsible for the majority of COs. This activity of Zhp3 suggests an evolutionarily conserved SC-independent strategy for balancing CO:NCO ratios. Moreover, we report a novel meiosis-specific protein, Sa15, as an interacting partner of Zhp3. Sa15 forms linear structures in meiotic prophase nuclei to which Zhp3 localizes. Sa15 is required for a wild-type level of CO formation. Its linear organization suggests the existence of an underlying chromosomal axis that serves as a scaffold for Zhp3 and other recombination proteins.
authors.affiliation: Department of Chromosome Biology, University of Vienna, Vienna Biocenter, 1030 Vienna, Austria.
authors.forename: Anura
authors.initials: A
authors.lastname: Shodhan
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences and.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Kataoka
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences and.
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Mochizuki
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences and.|Research Institute of Molecular Pathology, 1030 Vienna, Austria.
authors.forename: Maria
authors.initials: M
authors.lastname: Novatchkova
authors.affiliation: Department of Chromosome Biology, University of Vienna, Vienna Biocenter, 1030 Vienna, Austria josef.loidl@univie.ac.at.
authors.forename: Josef
authors.initials: J
authors.lastname: Loidl
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D003434:Crossing Over, Genetic / Q000502:physiology; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism; D008540:Meiosis / Q000502:physiology; D054829:RING Finger Domains; D011995:Recombination, Genetic / Q000502:physiology; D013573:Synaptonemal Complex / Q000378:metabolism*; D013768:Tetrahymena / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins