The 3′-5′ exonucleases

Over the past few years, several new 3'-5' exonucleases have been identified. In vitro studies of these enzymes have uncovered much about their potential functions in vivo, and certain organisms with a defect in 3'-5' exonucleases have an increased susceptibility to cancer, especially under conditions of stress. Here, we look at not only the newly discovered enzymes, but also at the roles of other 3'-5' exonucleases in the quality control of DNA synthesis, where they act as proofreading exonucleases for DNA polymerases during DNA replication, repair and recombination.