RecG controls DNA amplification at double-strand breaks and arrested replication forks

DNA amplification is a powerful mutational mechanism that is a hallmark of cancer and drug resistance. It is therefore important to understand the fundamental pathways that cells employ to avoid over-replicating sections of their genomes. Recent studies demonstrate that, in the absence of RecG, DNA amplification is observed at sites of DNA double-strand break repair (DSBR) and of DNA replication arrest that are processed to generate double-strand ends. RecG also plays a role in stabilising joint molecules formed during DSBR. We propose that RecG prevents a previously unrecognised mechanism of DNA amplification that we call reverse-restart, which generates DNA double-strand ends from incorrect loading of the replicative helicase at D-loops formed by recombination, and at arrested replication forks.