1ako: Difference between revisions

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==Overview==

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.

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.

==About this Structure==

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[[Category: Exodeoxyribonuclease III]]

[[Category: Single protein]]

[[Category: Cunningham, R.P.]]

[[Category: Cunningham, R P.]]

[[Category: Kuo, C.F.]]

[[Category: Kuo, C F.]]

[[Category: Mol, C.D.]]

[[Category: Mol, C D.]]

[[Category: Tainer, J.A.]]

[[Category: Tainer, J A.]]

[[Category: Thayer, M.M.]]

[[Category: Thayer, M M.]]

[[Category: ap-endonuclease]]

[[Category: dna repair]]

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[[Category: nuclease]]

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@@ Line 4: / Line 4: @@
 ==Overview==
-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'--&gt;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.
+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'--&gt;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.
 ==About this Structure==
@@ Line 14: / Line 14: @@
 [[Category: Exodeoxyribonuclease III]]
 [[Category: Single protein]]
-[[Category: Cunningham, R.P.]]
+[[Category: Cunningham, R P.]]
-[[Category: Kuo, C.F.]]
+[[Category: Kuo, C F.]]
-[[Category: Mol, C.D.]]
+[[Category: Mol, C D.]]
-[[Category: Tainer, J.A.]]
+[[Category: Tainer, J A.]]
-[[Category: Thayer, M.M.]]
+[[Category: Thayer, M M.]]
 [[Category: ap-endonuclease]]
 [[Category: dna repair]]
@@ Line 24: / Line 24: @@
 [[Category: nuclease]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Feb  3 09:30:44 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:45:33 2008''