The tumor suppressor homolog in fission yeast, myh1(+), displays a strong interaction with the checkpoint gene rad1(+).
The DNA glycosylase MutY is strongly conserved in evolution, and homologs are found in most eukaryotes and prokaryotes examined. This protein is implicated in repair of oxidative DNA damage, in particular adenine mispaired opposite 7,8-dihydro-8-oxoguanine. Previous investigations in Escherichia coli, fission yeast, and mammalian cells show an association of mutations in MutY homologs with a mutator phenotype and carcinogenesis. Eukaryotic MutY homologs physically associate with several proteins with a role in replication, DNA repair, and checkpoint signaling, specifically the trimeric 9-1-1 complex. In a genetic investigation of the fission yeast MutY homolog, myh1(+), we show that the myh1 mutation confers a moderately increased UV sensitivity alone and in combination with mutations in several DNA repair genes. The myh1 rad1, and to a lesser degree myh1 rad9, double mutants display a synthetic interaction resulting in enhanced sensitivity to DNA damaging agents and hydroxyurea. UV irradiation of myh1 rad1 double mutants results in severe chromosome segregation defects and visible DNA fragmentation, and a failure to activate the checkpoint. Additionally, myh1 rad1 double mutants exhibit morphological defects in the absence of DNA damaging agents. We also found a moderate suppression of the slow growth and UV sensitivity of rhp51 mutants by the myh1 mutation. Our results implicate fission yeast Myh1 in repair of a wider range of DNA damage than previously thought, and functionally link it to the checkpoint pathway.
Jansson
Kristina
K
Department of Cell and Molecular Biology, Lundberg Laboratory, Göteborg University, P.O. Box 462, Göteborg SE-405 30, Sweden.
Warringer
Jonas
J
Farewell
Anne
A
Park
Han-Oh
HO
Hoe
Kwang-Lae
KL
Kim
Dong-Uk
DU
Hayles
Jacqueline
J
Sunnerhagen
Per
P
D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000235:genetics; D004249:DNA Damage; D045647:DNA Glycosylases / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D004720:Endonucleases / Q000235:genetics*; D005800:Genes, Fungal; D006918:Hydroxyurea / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation; D011836:Radiation Tolerance / Q000235:genetics; D012568:Schizosaccharomyces / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics*; D014466:Ultraviolet Rays
D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D029702:Schizosaccharomyces pombe Proteins; C069930:rad9 protein; D004720:Endonucleases; C499354:rad1 protein, S pombe; D045647:DNA Glycosylases; D006918:Hydroxyurea