Download MendeleyA Novel Zinc Snap Motif Conveys Structural Stability to 3-Methyladenine DNA Glycosylase I
Kwon, K., Cao, C., Stivers, J.T.(2003) J Biol Chem 278: 19442-19446
- PubMed: 12654914
- DOI: https://doi.org/10.1074/jbc.M300934200
- Primary Citation of Related Structures:
1NKU - PubMed Abstract:
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.
Organizational Affiliation:
Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185, USA.
