Uncharacterized bacterial subgroup of the DEDDy 3'-5' exonuclease domain of family-B DNA polymerases
A subfamily of the 3'-5' exonuclease domain of family-B DNA polymerases. This subfamily is composed of uncharacterized bacterial family-B DNA polymerases. Family-B DNA polymerases contain an N-terminal DEDDy DnaQ-like exonuclease domain in the same polypeptide chain as the polymerase domain, similar to family-A DNA polymerases. This exonuclease domain contains three sequence motifs termed ExoI, ExoII and ExoIII, with a specific YX(3)D pattern at ExoIII. These motifs are involved in metal binding and catalysis. The exonuclease domain of family-B DNA polymerases has a fundamental role in proofreading activity. It contains a beta hairpin structure that plays an important role in active site switching in the event of a nucleotide misincorporation. Family-B DNA polymerases are predominantly involved in DNA replication and DNA repair.