Exonuclease
Exonucleases (ExN) cleave nucleotides at the end of a polynucleotide chain. In E. coli there are ExN I to VIII. ExN-I cleaves single-stranded DNA; ExN-II is associated with DNA polymerase; ExN-III cleaves double-stranded DNA; ExN-IV cleavage results in nucleoside monophosphate; ExN-V cleaves linear double-stranded DNA; ExN-VIII requires a free 5’ OH group for reacting. ExN were found in human and yeast as well.
3D Structures of exonuclease3D Structures of exonuclease
ExN-IExN-I
1fxx, 3c95 – EcExN-I – Escherichia coli
2qxf - EcExN-I + TMP
3hl8, 3hp9 - EcExN-I + inhibitor
3c94 - EcExN-I + DNA-binding C terminal peptide
ExN-IIIExN-III
2voa – ExN-III (mutant) + DNA – Archaeoglobus fulgidus
3g1k - MtExN-III – Methanothermobacter thermaautotrophicus
3g3c, 3g4t - MtExN-III + DNA
3fzi, 3g8v, 3g91 - MtExN-III (mutant)
3g00, 3g0r, 3g2c, 3g2d, 3g38, 3g3y, 3ga6 - MtExN-III (mutant) + DNA
3g0a - MtExN-III (mutant) + Mn
ExN-IVExN-IV
2jc4 – ExN-IV – Nisseria meningitides
ExN-VExN-V
1w36, 3k70 – EcExN-V α+β+γ + DNA hairpin
3e1s - EcExN-V RECD subunit
3gp8 - DrExN-V RECD subunit + DNA – Deinococcus radiodurans
3gpl - DrExN-V RECD subunit + DNA + ADPNP
ExN-VIIExN-VII
1vp7 – ExN-VII small subunit – Bordetella pertussis
ExN-VIIIExN-VIII
3h4r - EcExN-VIII C terminal (mutant)