Condensin HEAT Subunits Required for DNA Repair,Kinetochore/Centromere Function and Ploidy Maintenance in Fission Yeast |
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| Authors: | Xingya Xu Norihiko Nakazawa Mitsuhiro Yanagida |
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| Affiliation: | 1. Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa, Japan.; 2. Department of Genetics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.; University of Oklahoma, UNITED STATES, |
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| Abstract: | Condensin, a central player in eukaryotic chromosomal dynamics, contains five evolutionarily-conserved subunits. Two SMC (structural maintenance of chromosomes) subunits contain ATPase, hinge, and coiled-coil domains. One non-SMC subunit is similar to bacterial kleisin, and two other non-SMC subunits contain HEAT (similar to armadillo) repeats. Here we report isolation and characterization of 21 fission yeast (Schizosaccharomyces pombe) mutants for three non-SMC subunits, created using error-prone mutagenesis that resulted in single-amino acid substitutions. Beside condensation, segregation, and DNA repair defects, similar to those observed in previously isolated SMC and cnd2 mutants, novel phenotypes were observed for mutants of HEAT-repeats containing Cnd1 and Cnd3 subunits. cnd3-L269P is hypersensitive to the microtubule poison, thiabendazole, revealing defects in kinetochore/centromere and spindle assembly checkpoints. Three cnd1 and three cnd3 mutants increased cell size and doubled DNA content, thereby eliminating the haploid state. Five of these mutations reside in helix B of HEAT repeats. Two non-SMC condensin subunits, Cnd1 and Cnd3, are thus implicated in ploidy maintenance. |
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