Exonuclease

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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.
  • ExNX can degrade both single-stranded DNA and duplex DNA with 3'-5' polarity[2]
  • For phage ExN see Sand box 211.

in E. coli exonuclease I (PDB code 1fxx).[3] Water molecules shown as red spheres.

3D Structures of exonuclease

Exonuclease 3D structures


E. coli exonuclease I complex with phosphate, glycerol and Mg+2 ion (PDB code 1fxx)

Drag the structure with the mouse to rotate

ReferencesReferences

  1. ↑ 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:http://dx.doi.org/10.1385/1-59259-750-5:193
  2. ↑ 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
  3. ↑ 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

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