Regulation of telomere length by checkpoint genes in Schizosaccharomyces pombe.
We have studied telomere length in Schizosaccharomyces pombe strains carrying mutations affecting cell cycle checkpoints, DNA repair, and regulation of the Cdc2 protein kinase. Telomere shortening was found in rad1, rad3, rad17, and rad26 mutants. Telomere lengths in previously characterized rad1 mutants paralleled the replication checkpoint proficiency of those mutants. In contrast, rad9, chk1, hus1, and cds1 mutants had intact telomeres. No difference in telomere length was seen in mutants affected in the regulation of Cdc2, whereas some of the DNA repair mutants examined had slightly longer telomeres than did the wild type. Overexpression of the rad1(+) gene caused telomeres to elongate slightly. The kinetics of telomere shortening was monitored by following telomere length after disruption of the rad1(+) gene; the rate was approximately 1 nucleotide per generation. Wild-type telomere length could be restored by reintroduction of the wild-type rad1(+) gene. Expression of the Saccharomyces cerevisiae RCK1 protein kinase gene, which suppresses the radiation and hydroxyurea sensitivity of Sz. pombe checkpoint mutants, was able to attenuate telomere shortening in rad1 mutant cells and to increase telomere length in a wild-type background. The functional effects of telomere shortening in rad1 mutants were assayed by measuring loss of a linear and a circular minichromosome. A minor increase in loss rate was seen with the linear minichromosome, and an even smaller difference compared with wild-type was detected with the circular plasmid.
Dahlen
M
M
Department of Molecular Biology, Lundberg Laboratory, Goteborg University, S-405 30 Goteborg, Sweden.
Olsson
T
T
Kanter-Smoler
G
G
Ramne
A
A
Sunnerhagen
P
P
D016203:CDC2 Protein Kinase / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D015825:Chromosomes, Fungal / Q000235:genetics* / Q000648:ultrastructure; D004260:DNA Repair / Q000235:genetics; D045643:DNA Repair Enzymes; D004261:DNA Replication / Q000235:genetics; D004271:DNA, Fungal / Q000096:biosynthesis / Q000235:genetics; D004268:DNA-Binding Proteins; D004720:Endonucleases / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005800:Genes, Fungal; D007700:Kinetics; D009154:Mutation; D015221:Potassium Channels / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D029702:Schizosaccharomyces pombe Proteins; D016615:Telomere / Q000235:genetics* / Q000648:ultrastructure; D013696:Temperature
D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D015221:Potassium Channels; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D016203:CDC2 Protein Kinase; D004720:Endonucleases; C069266:RAD1 protein, S cerevisiae; C499354:rad1 protein, S pombe; D045643:DNA Repair Enzymes