26 research outputs found
Mutator Suppression and Escape from Replication ErrorβInduced Extinction in Yeast
Cells rely on a network of conserved pathways to govern DNA replication fidelity. Loss of polymerase proofreading or mismatch repair elevates spontaneous mutation and facilitates cellular adaptation. However, double mutants are inviable, suggesting that extreme mutation rates exceed an error threshold. Here we combine alleles that affect DNA polymerase Ξ΄ (Pol Ξ΄) proofreading and mismatch repair to define the maximal error rate in haploid yeast and to characterize genetic suppressors of mutator phenotypes. We show that populations tolerate mutation rates 1,000-fold above wild-type levels but collapse when the rate exceeds 10β3 inactivating mutations per gene per cell division. Variants that escape this error-induced extinction (eex) rapidly emerge from mutator clones. One-third of the escape mutants result from second-site changes in Pol Ξ΄ that suppress the proofreading-deficient phenotype, while two-thirds are extragenic. The structural locations of the Pol Ξ΄ changes suggest multiple antimutator mechanisms. Our studies reveal the transient nature of eukaryotic mutators and show that mutator phenotypes are readily suppressed by genetic adaptation. This has implications for the role of mutator phenotypes in cancer
Re-engineering a neuroprotective, clinical drug as a procognitive agent with high in vivo potency and with GABAA potentiating activity for use in dementia
The human pharmacokinetics of odanacatib, a novel cathepsin K inhibitor, predicted by interspecies scaling: a retrospective analysis
Cfi1 prevents premature exit from mitosis by anchoring Cdc14 phosphatase in the nucleolus
Cdc14 Early Anaphase Release, FEAR, Is Limited to the Nucleus and Dispensable for Efficient Mitotic Exit
A rapid and reagent-free bioassay for the detection of dioxin-like compounds and other aryl hydrocarbon receptor (AhR) agonists using autobioluminescent yeast
Analysis of Sec61p and Ssh1p interactions in the ER membrane using the split-ubiquitin system
Forkhead proteins control the outcome of transcription factor binding by antiactivation
Transcription factors with identical DNA-binding specificity often activate different genes in vivo. Yeast Ace2 and Swi5 are such activators, with targets we classify as Swi5-only, Ace2-only, or both. We define two unique regulatory modes. Ace2 and Swi5 both bind in vitro to Swi5-only genes such as HO, but only Swi5 binds and activates in vivo. In contrast, Ace2 and Swi5 both bind in vivo to Ace2-only genes, such as CTS1, but promoter-bound Swi5 fails to activate. We show that activation by Swi5 is prevented by the binding of the Forkhead factors Fkh1 and Fkh2, which recruit the Rpd3(Large) histone deacetylase complex to the CTS1 promoter. Global analysis shows that all Ace2-only genes are bound by both Ace2 and Swi5, and also by Fkh1/2. Genes normally activated by either Ace2 or Swi5 can be converted to Ace2-only genes by the insertion of Fkh-binding sites. Thus Fkh proteins, which function initially to activate SWI5 and ACE2, subsequently function as Swi5-specific antiactivators