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 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-X can degrade both single-stranded DNA and duplex DNA with 3'-5' polarity[2]
- Trex ExN degrades single-stranded DNA generated from processing of aberrant replication intermediates[3]
Mg coordination site in E. coli exonuclease I (PDB code 1fxx).[4] Water molecules shown as red spheres.
3D Structures of exonuclease
Exonuclease 3D structures
- ↑ Mukherjee D, Fritz DT, Kilpatrick WJ, Gao M, Wilusz J. Analysis of RNA exonucleolytic activities in cellular extracts. Methods Mol Biol. 2004;257:193-212. PMID:14770007 doi:https://dx.doi.org/10.1385/1-59259-750-5:193
- ↑ Viswanathan M, Lovett ST. Exonuclease X of Escherichia coli. A novel 3'-5' DNase and Dnaq superfamily member involved in DNA repair. J Biol Chem. 1999 Oct 15;274(42):30094-100. PMID:10514496 doi:10.1074/jbc.274.42.30094
- ↑ Yang YG, Lindahl T, Barnes DE. Trex1 exonuclease degrades ssDNA to prevent chronic checkpoint activation and autoimmune disease. Cell. 2007 Nov 30;131(5):873-86. doi: 10.1016/j.cell.2007.10.017. PMID:18045533 doi:https://dx.doi.org/10.1016/j.cell.2007.10.017
- ↑ Breyer WA, Matthews BW. Structure of Escherichia coli exonuclease I suggests how processivity is achieved. Nat Struct Biol. 2000 Dec;7(12):1125-8. PMID:11101894 doi:10.1038/81978
