Schizosaccharomyces pombe RanGAP homolog, SpRna1, is required for centromeric silencing and chromosome segregation.
We isolated 11 independent temperature-sensitive (ts) mutants of Schizosaccharomyces pombe RanGAP, SpRna1 that have several amino acid changes in the conserved domains of RanGAP. Resulting Sprna1ts showed a strong defect in mitotic chromosome segregation, but did not in nucleocytoplasmic transport and microtubule formation. In addition to Sprna1+ and Spksp1+, the clr4+ (histone H3-K9 methyltransferase), the S. pombe gene, SPAC25A8.01c, designated snf2SR+ (a member of the chromatin remodeling factors, Snf2 family with DNA-dependent ATPase activity), but not the spi1+ (S. pombe Ran homolog), rescued a lethality of Sprna1ts. Both Clr4 and Snf2 were reported to be involved in heterochromatin formation essential for building the centromeres. Consistently, Sprna1ts was defective in gene-silencing at the centromeres. But a silencing at the telomere, another heterochromatic region, was normal in all of Sprna1ts strains, indicating SpRna1 in general did not function for a heterochromatin formation. snf2SR+ rescued a centromeric silencing defect and Deltaclr4+ was synthetic lethal with Sprna1ts. Taken together, SpRna1 was suggested to function for constructing the centromeres, by cooperating with Clr4 and Snf2SR. Loss of SpRna1 activity, therefore, caused chromosome missegregation.
Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Ayumi
A
Kusano
Tomoko
T
Yoshioka
Hitoshi
H
Nishijima
Hideo
H
Nishitani
Takeharu
T
Nishimoto
D021581:Active Transport, Cell Nucleus; D002467:Cell Nucleus / Q000378:metabolism; D002503:Centromere / Q000648:ultrastructure*; D020090:Chromosome Segregation; D003593:Cytoplasm / Q000378:metabolism; D004252:DNA Mutational Analysis; D020690:GTPase-Activating Proteins / Q000096:biosynthesis* / Q000502:physiology*; D020868:Gene Silencing; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006570:Heterochromatin / Q000378:metabolism; D006657:Histones; D008856:Microscopy, Fluorescence; D008938:Mitosis; D008954:Models, Biological; D008958:Models, Molecular; D009154:Mutation; D017434:Protein Structure, Tertiary; D012568:Schizosaccharomyces / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins; D013696:Temperature
D020690:GTPase-Activating Proteins; D006570:Heterochromatin; D006657:Histones; D029702:Schizosaccharomyces pombe Proteins; C499298:rna1 protein, S pombe; D049452:Green Fluorescent Proteins