This domain is found at the C-terminal end of QDE-2-interacting protein from Neurospora crassa, DNA polymerase III subunit epsilon from Treponema pallidum (DnaQ) and similar fungal proteins that belong to the DnaQ-like (or DEDDh) exonuclease superfamily. These proteins catalyze the excision of nucleoside monophosphates at the DNA or RNA termini in the 3'-5' direction. Most DEDDh exonucleases are the proofreading subunits (epsilon) or domains of bacterial DNA polymerase III, the main replicating enzyme in bacteria, which functions as the chromosomal replicase. This domain shows an alpha -beta configuration.

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