DNA replication is a critical process for all different life forms and initiates from sites in the genome called ‘replication origins’. In budding yeast, replication origins correspond to autonomously replicating sequences (ARSs). In the genomes of some budding yeasts, however, and in the fission yeast Schizosaccharomyces pombe, origins are site-specific but not sequence-specific. In metazoan cells, origins lack sequence-specificity. The origin recognition complex (ORC) and cell division cycle 6 (Cdc6) proteins bind to budding yeast origins in a sequence-specific manner.
This lecture will discuss the differences between ORC and Cdc6 in yeast and human cells and how the initiation of DNA replication is controlled by these cells.
The evolution of DNA replication origin specification has co-evolved with mechanisms of epigenetic gene silencing, a process that ensures that silent transcriptional states of gene expression are inherited from one generation to the next.