Checkpoint kinase interaction with DNA polymerase alpha regulates replication progression during stress.

In eukaryotes, replication stress activates a checkpoint response, which facilitates genome duplication by stabilising the replisome. How the checkpoint kinases regulate the replisome remains poorly understood. The aim of this study is to identify new targets of checkpoint kinases within the replisome during replication stress.

Senescence in yeast is associated with amplified linear fragments of chromosome XII rather than ribosomal DNA circle accumulation.

The massive accumulation of extrachromosomal ribosomal DNA circles (ERCs) in yeast mother cells has been long cited as the primary driver of replicative ageing. ERCs arise through ribosomal DNA (rDNA) recombination, and a wealth of genetic data connects rDNA instability events giving rise to ERCs with shortened life span and other ageing pathologies. However, we understand little about the molecular effects of ERC accumulation.

Dietary change without caloric restriction maintains a youthful profile in ageing yeast.

Caloric restriction increases lifespan and improves ageing health, but it is unknown whether these outcomes can be separated or achieved through less severe interventions. Here, we show that an unrestricted galactose diet in early life minimises change during replicative ageing in budding yeast, irrespective of diet later in life. Average mother cell division rate is comparable between glucose and galactose diets, and lifespan is shorter on galactose, but markers of senescence and the progressive dysregulation of gene expression observed on glucose are minimal on galactose, showing that these are not intrinsic aspects of replicative ageing but rather associated processes.

Stimulation of adaptive gene amplification by origin firing under replication fork constraint.

Adaptive mutations can cause drug resistance in cancers and pathogens, and increase the tolerance of agricultural pests and diseases to chemical treatment. When and how adaptive mutations form is often hard to discern, but we have shown that adaptive copy number amplification of the copper resistance gene CUP1 occurs in response to environmental copper due to CUP1 transcriptional activation. Here we dissect the mechanism by which CUP1 transcription in budding yeast stimulates copy number variation (CNV).

Abo1, a conserved bromodomain AAA-ATPase, maintains global nucleosome occupancy and organisation.

Maintenance of the correct level and organisation of nucleosomes is crucial for genome function. Here, we uncover a role for a conserved bromodomain AAA-ATPase, Abo1, in the maintenance of nucleosome architecture in fission yeast. Cells lacking abo1(+) experience both a reduction and mis-positioning of nucleosomes at transcribed sequences in addition to increased intragenic transcription, phenotypes that are hallmarks of defective chromatin re-establishment behind RNA polymerase II.