Exonuclease V is a monomeric 5' deoxyribonuclease that is localised in the nucleus. It degrades single-stranded, but not double-stranded, DNA from the 5'-end, and the products are dinucleotides, except the 3'-terminal tri- and tetranucleotides, which are not degraded. The initial hydrolytic cut of exonuclease V on the dephosphorylated substrate produces a mixture of dinucleoside monophosphates and trinucleoside diphosphates. The enzyme is processive in action [1]. Exo5 is specific for single-stranded DNA and does not hydrolyze RNA. However, Exo5 has the capacity to slide across 5' double-stranded DNA or 5' RNA sequences and resume cutting two nucleotides downstream of the double-stranded-to-single-stranded junction or RNA-to-DNA junction, respectively [3].

1: Exonuclease V from Saccharomyces cerevisiae. A 5'----3'-deoxyribonuclease that produces dinucleotides in a sequential fashion. Burgers PM, Bauer GA, Tam L; J Biol Chem. 1988;263:8099-8105. PMID:3286646

2: Detection of eQTL modules mediated by activity levels of transcription factors. Sun W, Yu T, Li KC; Bioinformatics. 2007;23:2290-2297. PMID:17599927

3: Yeast exonuclease 5 is essential for mitochondrial genome maintenance. Burgers PM, Stith CM, Yoder BL, Sparks JL; Mol Cell Biol. 2010;30:1457-1466. PMID:20086101