Publication Date:
1992-10-16
Description:
The crystal structure of the DNA repair enzyme endonuclease III, which recognizes and cleaves DNA at damaged bases, has been solved to 2.0 angstrom resolution with an R factor of 0.185. This iron-sulfur [4Fe-4S] enzyme is elongated and bilobal with a deep cleft separating two similarly sized domains: a novel, sequence-continuous, six-helix domain (residues 22 to 132) and a Greek-key, four-helix domain formed by the amino-terminal and three carboxyl-terminal helices (residues 1 to 21 and 133 to 211) together with the [4Fe-4S] cluster. The cluster is bound entirely within the carboxyl-terminal loop with a ligation pattern (Cys-X6-Cys-X2-Cys-X5-Cys) distinct from all other known [4Fe-4S] proteins. Sequence conservation and the positive electrostatic potential of conserved regions identify a surface suitable for binding duplex B-DNA across the long axis of the enzyme, matching a 46 angstrom length of protected DNA. The primary role of the [4Fe-4S] cluster appears to involve positioning conserved basic residues for interaction with the DNA phosphate backbone. The crystallographically identified inhibitor binding region, which recognizes the damaged base thymine glycol, is a seven-residue beta-hairpin (residues 113 to 119). Location and side chain orientation at the base of the inhibitor binding site implicate Glu112 in the N-glycosylase mechanism and Lys120 in the beta-elimination mechanism. Overall, the structure reveals an unusual fold and a new biological function for [4Fe-4S] clusters and provides a structural basis for studying recognition of damaged DNA and the N-glycosylase and apurinic/apyrimidinic-lyase mechanisms.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kuo, C F -- McRee, D E -- Fisher, C L -- O'Handley, S F -- Cunningham, R P -- Tainer, J A -- GM 46312/GM/NIGMS NIH HHS/ -- HL07695/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1992 Oct 16;258(5081):434-40.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Scripps Research Institute, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1411536" target="_blank"〉PubMed〈/a〉
Keywords:
Bacterial Proteins/ultrastructure
;
Base Sequence
;
Crystallography
;
Cysteine/chemistry
;
*DNA Repair
;
DNA-Binding Proteins/*ultrastructure
;
Deoxyribonuclease (Pyrimidine Dimer)
;
Endodeoxyribonucleases/*ultrastructure
;
Iron-Sulfur Proteins/*ultrastructure
;
Models, Molecular
;
Molecular Sequence Data
;
Oligodeoxyribonucleotides/metabolism
;
Protein Conformation
;
Protein Structure, Secondary
;
Protein Structure, Tertiary
;
X-Ray Diffraction
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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