Regulation of spindle behaviour by DNA replication and damage checkpoints in budding yeast

Abstract

Accurate genetic transmission is essential for reproduction in all species. Eukaryotic organisms have evolved surveillance mechanisms, known as checkpoints, to monitor the integrity of the genome, particularly during the S and G2 phases and to halt the cell cycle to enable repairs to be undertaken. It has commonly been assumed that cell cycle is halted by inhibitory phosphorylation of Cdk1. We test this assumption in budding yeast S.cerevisiae S phase, and find that crucial mitotic events are dispensable for premature chromosome segregation seen in checkpoint mutant mec1, implying that alternative mechanisms of spindle regulation may exist. We confirm this finding in the DNA damage checkpoint context, and propose a mechanism by which this may be brought about.