Please use this identifier to cite or link to this item: http://hdl.handle.net/20.500.12779/5056
Title: A prokaryotic superoxide dismutase paralog lacking two Cu ligands: From largely unstructured in solution to ordered in the crystal
Authors: L., Banci
I., Bertini
V., Calderone
F., Cramaro
R. D., Conte
A., Fantoni
Mangani, Stefano 
A., Quattrone
M. S., Viezzoli
Keywords: x-ray; NMR; crystal structure; bacterial superoxide dismutase; molten globule; zinc; copper
Issue Date: 2005
Project: None 
Journal: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Abstract: 
Little is known about prokaryotic homologs of Cu,Zn superoxide dismutase (SOD), an enzyme highly conserved among eukaryotic species. In 138 Archaea and Bacteria genomes, 57 of these putative homologs were found, 11 of which lack at least one of the metal ligands. Both the solution and the crystal structures of the SOD-like protein from Bacillus subtilis, lacking two Cu ligands and found to be enzymatically inactive, were determined. In solution, the protein is monomeric. The available nuclear Overhauser effects, together with chemical-shift index values, allowed us to define and to recognize the typical Cu,Zn SOD Greek beta-barrel but with largely unstructured loops (which, therefore, sample a wide range of conformations). On the contrary, in the crystal structure (obtained in the presence of slight excess of Zn), the protein is well structured and organized in covalent dimers held by a symmetric bridge consisting of a Zn ion bound to an Asp-His dyad in a tetrahedral geometry. Couples of dimers held by hydrophobic interactions and H bonds are further organized in long chains. The order/disorder transition is discussed in terms of metal binding and physical state.
Description: 
47934
URI: http://hdl.handle.net/20.500.12779/5056
ISSN: 0027-8424
DOI: 10.1073/pnas.0502450102
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