There is an error in the last sentence of the fourth paragraph of the Introduction. The correct sentence is: Then an exchange of ADP with ATP in ATP domains of MutS takes place (Figure 1, step 5, a) and there is formed an ultimate recognition complex, which being in the “sliding clamp” conformation initiates an MMR reaction cascade involving MutL and MutH (Figure 1, step i, a).

There are multiple errors in the structures of the duplexes I–IV (5′→3′/3′→5′) shown in the “Synthetic DNA Fragments” subsection of the Materials and Methods. Please see the correct structures here.

CAAGCCTATGCCCTCAGCACCCAGGGTGCC I (G/C)

GTTCGGATACGGGAGTCGTGGGTCCCACGG

CAAGCCTATGCCCTCAGCACCCAGGGTGCC II (G/T)

GTTCGGATACGGGAGTCGTGGGTTCCACGG

CAAGCCTATGCCCTCAGCACCCAG-GGTGCC III (G/Tg)

GTTCGGATACGGGAGTCGTGGGTTgCCACGG

CAAGCCTATGCCCTCAGCACCCAA-GGTGCC IV (A/Tg)

GTTCGGATACGGGAGTCGTGGGTTgCCACGG