Microsatellite instability articles from across Nature Portfolio

DNA replication of repetitive sequences was recreated in a test tube using purified components. DNA alone was sufficient to induce stalling. Both stalling and recovery were dictated by the capacity of DNA to fold into unusual secondary structures.

Defects in DNA mismatch repair (MMR) have been linked to inherited and sporadic cancers. Here the authors demonstrate that the DNA repair protein Rad27 (human FEN1) functions in one of three redundant mispair excision pathways, where its flap endonuclease activity catalyzes mispair excision.

Reyes et al. identified and characterized dominant mutations in the MutL homolog MLH2 (in S. cerevisiae) and PMS1 (in humans) causing an increased mutator phenotype. Based on their findings, they propose that Mlh2/hPMS1-Mlh1 mutant complexes can act as roadblocks on DNA preventing mismatch repair function.