Abstract
PP2ACdc55 is a highly conserved serine-threonine protein phosphatase that is involved in diverse cellular processes. In budding yeast, meiotic cells lacking PP2ACdc55 activity undergo a premature exit from meiosis I which results in a failure to form bipolar spindles and divide nuclei. This defect is largely due to its role in negatively regulating the Cdc Fourteen Early Anaphase Release (FEAR) pathway. PP2ACdc55 prevents nucleolar release of the Cdk (Cyclin-dependent kinase)-antagonising phosphatase Cdc14 by counteracting phosphorylation of the nucleolar protein Net1 by Cdk. CDC55 was identified in a genetic screen for monopolins performed by isolating suppressors of spo11Δ spo12Δ lethality suggesting that Cdc55 might have a role in meiotic chromosome segregation. We investigated this possibility by isolating cdc55 alleles that suppress spo11Δ spo12Δ lethality and show that this suppression is independent of PP2ACdc55’s FEAR function. Although the suppressor mutations in cdc55 affect reductional chromosome segregation in the absence of recombination, they have no effect on chromosome segregation during wild type meiosis. We suggest that Cdc55 is required for reductional chromosome segregation during achiasmate meiosis and this is independent of its FEAR function.
Highlights
PP2ACdc[55] is a highly conserved serine-threonine protein phosphatase that is involved in diverse cellular processes
We suggest that PP2ACdc[55] is required for reductional chromosome segregation in the absence of recombination and that this function is distinct from its role in the Fourteen Early Anaphase Release (FEAR) pathway
PP2ACdc[55] may have a role in accurate meiotic chromosome segregation that is distinct from its FEAR function
Summary
PP2ACdc[55] is a highly conserved serine-threonine protein phosphatase that is involved in diverse cellular processes. Meiotic cells lacking PP2ACdc[55] activity undergo a premature exit from meiosis I which results in a failure to form bipolar spindles and divide nuclei This defect is largely due to its role in negatively regulating the Cdc Fourteen Early Anaphase Release (FEAR) pathway. PP2ACdc[55] prevents nucleolar release of the Cdk (Cyclin-dependent kinase)-antagonising phosphatase Cdc[14] by counteracting phosphorylation of the nucleolar protein Net[1] by Cdk. CDC55 was identified in a genetic screen for monopolins performed by isolating suppressors of spo11Δ spo12Δ lethality suggesting that Cdc[55] might have a role in meiotic chromosome segregation. To assess PP2ACdc55’s role in meiotic chromosome segregation, we performed a genetic screen and isolated two classes of suppressor mutations within the CDC55 ORF. We suggest that PP2ACdc[55] is required for reductional chromosome segregation in the absence of recombination and that this function is distinct from its role in the FEAR pathway
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