5'->3' double-stranded DNA exonuclease involved in mismatch repair and eventually also in mitotic recombination between direct repeats. Also has a minor role in the correction of large DNA mismatches that occur in the heteroduplex DNA during meiotic recombination at the HIS4 locus. Binds 2 magnesium ions per subunit. They probably participate in the reaction catalyzed by the enzyme. May bind an additional third magnesium ion after substrate binding. Inactivated by calcium and zinc ions. Interacts with mismatch repair protein MSH2. Present with 672 molecules/cell in log phase SD medium. Belongs to the XPG/RAD2 endonuclease family. EXO1 subfamily.