How to stop after copying the genome Replication is highly regulated: Failure to copy any part of the genome or copying parts of it more than once can cause genome instability with potentially disastrous consequences. Maric et al. and Priego Moreno et al. show that the DNA replication machinery, which stably encircles DNA during the duplication process, is actively disassembled once replication is complete (see the Perspective by Bell). The protein ring encircling the DNA is covalently modified, which allows it to be opened and the whole replication complex to be removed from DNA by a special disassembly complex. Science , this issue 10.1126/science.1253596 , p. 477 ; see also p. 418