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From Proteopedia
NMR Solution Structure of Zinc-binding protein 3-methyladenine DNA glycosylase I (TAG)
Structural highlights
Function3MG1_ECOLI Hydrolysis of the deoxyribose N-glycosidic bond to excise 3-methyladenine from the damaged DNA polymer formed by alkylation lesions. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe Escherichia coli 3-methyladenine DNA glycosylase I (TAG) is a DNA repair enzyme that excises 3-methyladenine in DNA and is the smallest member of the helix-hairpin-helix (HhH) superfamily of DNA glycosylases. Despite many studies over the last 25 years, there has been no suggestion that TAG was a metalloprotein. However, here we establish by heteronuclear NMR and other spectroscopic methods that TAG binds 1 eq of Zn2+ extremely tightly. A family of refined NMR structures shows that 4 conserved residues contributed from the amino- and carboxyl-terminal regions of TAG (Cys4, His17, His175, and Cys179) form a Zn2+ binding site. The Zn2+ ion serves to tether the otherwise unstructured amino- and carboxyl-terminal regions of TAG. We propose that this unexpected "zinc snap" motif in the TAG family (CX(12-17)HX(approximately 150)HX(3)C) serves to stabilize the HhH domain thereby mimicking the functional role of protein-protein interactions in larger HhH superfamily members. A novel zinc snap motif conveys structural stability to 3-methyladenine DNA glycosylase I.,Kwon K, Cao C, Stivers JT J Biol Chem. 2003 May 23;278(21):19442-6. Epub 2003 Mar 24. PMID:12654914[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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