1AKO

EXONUCLEASE III FROM ESCHERICHIA COLI

Summary for 1AKO

• Entry DOI: 10.2210/pdb1ako/pdb
• Descriptor: EXONUCLEASE III (2 entities in total)
• Functional Keywords: nuclease, exonuclease, ap-endonuclease, dna repair
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 31011.17

Authors

Mol, C.D.,Kuo, C.-F.,Thayer, M.M.,Cunningham, R.P.,Tainer, J.A. (deposition date: 1997-05-26, release date: 1997-08-20, Last modification date: 2024-02-07)

Primary citation

Mol, C.D.,Kuo, C.F.,Thayer, M.M.,Cunningham, R.P.,Tainer, J.A.
Structure and function of the multifunctional DNA-repair enzyme exonuclease III.
Nature, 374:381-386, 1995

PubMed Abstract: The repair of DNA requires the removal of abasic sites, which are constantly generated in vivo both spontaneously and by enzymatic removal of uracil, and of bases damaged by active oxygen species, alkylating agents and ionizing radiation. The major apurinic/apyrimidinic (AP) DNA-repair endonuclease in Escherichia coli is the multifunctional enzyme exonuclease III, which also exhibits 3'-repair diesterase, 3'-->5' exonuclease, 3'-phosphomonoesterase and ribonuclease activities. We report here the 1.7 A resolution crystal structure of exonuclease III which reveals a 2-fold symmetric, four-layered alpha beta fold with similarities to both deoxyribonuclease I and RNase H. In the ternary complex determined at 2.6 A resolution, Mn2+ and dCMP bind to exonuclease III at one end of the alpha beta-sandwich, in a region dominated by positive electrostatic potential. Residues conserved among AP endonucleases from bacteria to man cluster within this active site and appear to participate in phosphate-bond cleavage at AP sites through a nucleophilic attack facilitated by a single bound metal ion.

PubMed: 7885481
DOI: 10.1038/374381a0

Experimental method

X-RAY DIFFRACTION (1.7 Å)