InterPro domain: IPR037315

Exonuclease-1 (EXO1) is a 5'-3' exonuclease that functions in DNA mismatch repair (MMR), double-strand break repair, replication and recombination [ 1 , 2 , 3 ]. It also possesses a flap-endonuclease activity [ 4 , 4 ].

This entry represents the H3TH (helix-3-turn-helix) domain of EXO1. The H3TH domain has an extended loop with at least three turns between the first two helices, and only three of the four helices appear to be conserved. Together with the helical arch and network of amino acids interacting with metal binding ions, the H3TH region defines a positively charged active-site DNA-binding groove in structure-specific 5' nucleases [ 5 ].

1. Reconstitution of 5'-directed human mismatch repair in a purified system. Cell 122, 693-705
2. Characterization of human exonuclease 1 in complex with mismatch repair proteins, subcellular localization and association with PCNA. Oncogene 23, 1457-68
3. Characterization of nuclease-dependent functions of Exo1p in Saccharomyces cerevisiae. DNA Repair (Amst.) 1, 895-912
4. The RAD2 domain of human exonuclease 1 exhibits 5' to 3' exonuclease and flap structure-specific endonuclease activities. J. Biol. Chem. 274, 37763-9
5. Modeling of flap endonuclease interactions with DNA substrate. J. Mol. Biol. 328, 537-54