DNA mismatch repair and genetic instability

Mismatch repair (MMR) systems play a central role in promoting genetic stab ility by repairing DNA replication errors, inhibiting recombination between non-identical DNA sequences and participating in responses to DNA damage. The discovery of a link between human cancer and MMR defects has led to an explosion of research on eukaryotic MMR. The key proteins in MMR are highly conserved from bacteria to mammals, and this conservation has been critica l for defining the components of eukaryotic MMR systems. In eukaryotes, the re are multiple homologs of the key bacterial MutS and MutL MMR proteins, a nd these homologs form heterodimers that have discrete roles in MMR-related processes. This review describes the genetic and biochemical approaches us ed to study MMR, and summarizes the diverse roles that MMR proteins play in maintaining genetic stability.