Exonucleases (ExN) cleave nucleotides at the end of a polynucleotide chain[1]. In E. coli there are ExN I to VIII. ExN were found in human and yeast as well.
- ExN-I is a 5'-3' ExN cleaves double-stranded DNA[2].
- 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 degrades linear duplex DNA[3] and requires a free 5’ OH group for reacting.
- ExN-X can degrade both single-stranded DNA and duplex DNA with 3'-5' polarity[4]
- Trex ExN degrades single-stranded DNA generated from processing of aberrant replication intermediates[5]
in E. coli exonuclease I (PDB code 1fxx).[6] Water molecules shown as red spheres.
3D Structures of exonuclease
Exonuclease 3D structures