Intricacies in ATP-dependent clamp loading: variations across replication systems

DNA replication requires the coordinated effort of many proteins to create- a highly processive biomachine able to replicate entire genomes in a single process. The clamp proteins confer on replisomes this property of processi vity but in turn require clamp loaders for their functional assembly onto D NA. A more detailed view of the mechanisms for holoenzyme assembly in repli cation systems has been obtained from the advent of novel solution experime nts and the appearance of low- and high-resolution structures for the clamp loaders.