1nku
From Proteopedia
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NMR Solution Structure of Zinc-binding protein 3-methyladenine DNA glycosylase I (TAG)
Overview
The 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.
About this Structure
1NKU is a Single protein structure of sequence from Escherichia coli with ZN as ligand. Active as DNA-3-methyladenine glycosylase I, with EC number 3.2.2.20 Full crystallographic information is available from OCA.
Reference
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
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