Abstract
Inactivation of the budding yeast telomere binding protein Cdc13 results in abnormal telomeres (exposed long G-strands) and activation of the DNA damage checkpoint. In the current study, we show that inactivation of Cdc13p induces apoptotic signals in yeast, as evidenced by caspase activation, increased reactive oxygen species production, and flipping of phosphatidylserine in the cytoplasmic membrane. These apoptotic signals were suppressed in a mitochondrial (rho(o)) mutant. Moreover, mitochondrial proteins (e.g. MTCO3) were identified as multicopy suppressors of cdc13-1, suggesting the involvement of mitochondrial functions in telomere-initiated apoptotic signaling. These telomere-initiated apoptotic signals were also shown to depend on MEC1, but not TEL1, and were antagonized by MRE11. Our results are consistent with a model in which single-stranded G-tails in the cdc13-1 mutant trigger MEC1-dependent apoptotic signaling in yeast.
Highlights
Cdc13p is a budding yeast telomere binding protein [1,2,3]
We show that inactivation of Cdc13p induces apoptotic signals in yeast, as evidenced by caspase activation, increased reactive oxygen species production, and flipping of phosphatidylserine in the cytoplasmic membrane
A caspase-like protease Yca1p has been identified in yeast and was found to regulate yeast cell death induced by H2O2 treatment [12]
Summary
Cdc13p is a budding yeast telomere binding protein [1,2,3]. Cdc13p appears to be a multifunctional protein involved in both telomere replication and protection [1,2,3,4]. Mitochondrial proteins (e.g. MTCO3) were identified as multicopy suppressors of cdc13-1, suggesting the involvement of mitochondrial functions in telomere-initiated apoptotic signaling. Our results are consistent with a model in which single-stranded G-tails in the cdc13-1 mutant trigger MEC1-dependent apoptotic signaling in yeast.
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