Dbl2 Regulates Rad51 and DNA Joint Molecule Metabolism to Ensure Proper Meiotic Chromosome Segregation.
To identify new proteins required for faithful meiotic chromosome segregation, we screened a Schizosaccharomyces pombe deletion mutant library and found that deletion of the dbl2 gene led to missegregation of chromosomes during meiosis. Analyses of both live and fixed cells showed that dbl2Δ mutant cells frequently failed to segregate homologous chromosomes to opposite poles during meiosis I. Removing Rec12 (Spo11 homolog) to eliminate meiotic DNA double-strand breaks (DSBs) suppressed the segregation defect in dbl2Δ cells, indicating that Dbl2 acts after the initiation of meiotic recombination. Analyses of DSBs and Holliday junctions revealed no significant defect in their formation or processing in dbl2Δ mutant cells, although some Rec12-dependent DNA joint molecules persisted late in meiosis. Failure to segregate chromosomes in the absence of Dbl2 correlated with persistent Rad51 foci, and deletion of rad51 or genes encoding Rad51 mediators also suppressed the segregation defect of dbl2Δ. Formation of foci of Fbh1, an F-box helicase that efficiently dismantles Rad51-DNA filaments, was impaired in dbl2Δ cells. Our results suggest that Dbl2 is a novel regulator of Fbh1 and thereby Rad51-dependent DSB repair required for proper meiotic chromosome segregation and viable sex cell formation. The wide conservation of these proteins suggests that our results apply to many species.
Department of Membrane Biochemistry, Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Ivanka pri Dunaji, Slovakia.|Department of Chromosome Biology, Max F. Perutz Laboratories (MFPL), University of Vienna, Vienna, Austria.
Silvia
S
Polakova
Department of Genetics, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia.
Lucia
L
Molnarova
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America.
Randy W
RW
Hyppa
Department of Chromosome Biology, Max F. Perutz Laboratories (MFPL), University of Vienna, Vienna, Austria.
Zsigmond
Z
Benko
Department of Membrane Biochemistry, Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Ivanka pri Dunaji, Slovakia.
Ivana
I
Misova
IMP/IMBA Bioinformatics Core Facility, Research Institute of Molecular Pathology (IMP), Vienna Biocenter, Vienna, Austria.
Alexander
A
Schleiffer
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America.
Gerald R
GR
Smith
Department of Chromosome Biology, Max F. Perutz Laboratories (MFPL), University of Vienna, Vienna, Austria.|Department of Genetics, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia.
Juraj
J
Gregan
D020090:Chromosome Segregation / Q000235:genetics*; D053903:DNA Breaks, Double-Stranded; D004265:DNA Helicases / Q000378:metabolism*; D004260:DNA Repair / Q000235:genetics*; D045566:DNA, Cruciform / Q000235:genetics; D004271:DNA, Fungal / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000235:genetics; D017353:Gene Deletion; D015723:Gene Library; D045565:Holliday Junction Resolvases / Q000378:metabolism; D008540:Meiosis / Q000235:genetics; D051135:Rad51 Recombinase / Q000235:genetics*; D012568:Schizosaccharomyces / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics* / Q000378:metabolism*; D000099257:Meiotic Recombination Protein SPO11
D004265:DNA Helicases; D045566:DNA, Cruciform; D004271:DNA, Fungal; D004706:Endodeoxyribonucleases; D045565:Holliday Junction Resolvases; D051135:Rad51 Recombinase; D029702:Schizosaccharomyces pombe Proteins; D000099257:Meiotic Recombination Protein SPO11; C583967:Dbl2 protein, S pombe; C504739:Fbh1 protein, S pombe