Helicase Loading at Chromosomal Origins of Replication

Loading of the replicative DNA helicase at origins of replication is of central importance in DNA replication. As the first of the replication fork proteins assemble at chromosomal origins of replication, the loaded helicase is required for the recruitment of the rest of the replication machinery. In this work, we review the current knowledge of helicase loading at Escherichia coli and eukaryotic origins of replication. In each case, this process requires both an origin recognition protein as well as one or more additional proteins. Comparison of these events shows intriguing similarities that suggest a similar underlying mechanism, as well as critical differences that likely reflect the distinct processes that regulate helicase loading in bacterial and eukaryotic cells.