SRA

DNA replication initiates from defined locations called replication origins; some origins are highly active whereas others are dormant and rarely used. Origins also differ in their activation time resulting in particular genomic regions replicating at characteristic times and in a defined temporal order. Here we report the comparison of genome replication in four budding yeast species: Saccharomyces cerevisiae, S. paradoxus, S. arboricolus and S. bayanus. First, we find that the locations of active origins are predominantly conserved between species, whereas dormant origins are poorly conserved. Second, we generated genome-wide replication profiles for each of these species and discovered that the temporal order of genome replication is highly conserved. Therefore, active origins are not only conserved in location, but also activation time. Only a minority of these conserved origins show differences in activation time between these species. To gain insight as to the mechanisms by which origin activation time is regulated we generated replication profiles for a S. cerevisiae / S. bayanus hybrid strain and find that there are both local and global regulators of origin function. Overall design: Measurement of genome replication time from 4 budding yeast species (Saccharomyces cerevisiae, S. paradoxus, S. arboricolus and S. bayanus) and a hybrid (between Saccharomyces cerevisiae and S. bayanus). For each strain two samples were analysed: a replicating sample (from S phase) and a non-replicating sample (from G2 phase) The reference genome sequences for each yeast species are available as Series supplementary file [sac*.fa]