HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplemental Research Data Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Muñoz, I. G. Articles by Montoya, G. Search for Related Content PubMed PubMed Citation Articles by Muñoz, I. G. Articles by Montoya, G. Social Bookmarking                   What's this?

The crystal structure of an eukaryotic iron superoxide dismutase suggests intersubunit cooperation during catalysis

¹ Structural Biology and Biocomputing Program, Spanish National Cancer Center (CNIO), Macromolecular Crystallography Group, 28029 Madrid, Spain
² Departamento de Ciencias del Medio Natural, Universidad Pública de Navarra, 31006 Pamplona, Spain
³ Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (CSIC), 50059 Zaragoza, Spain

(RECEIVED July 8, 2004; FINAL REVISION September 30, 2004; ACCEPTED September 30, 2004)

Superoxide dismutases (SODs) are a family of metalloenzymes that catalyze the dismutation of superoxide anion radicals into molecular oxygen and hydrogen peroxide. Iron superoxide dismutases (FeSODs) are only expressed in some prokaryotes and plants. A new and highly active FeSOD with an unusual subcellular localization has recently been isolated from the plant Vigna unguiculata (cowpea). This protein functions as a homodimer and, in contrast to the other members of the SOD family, is localized to the cytosol. The crystal structure of the recombinant enzyme has been solved and the model refined to 1.97 Å resolution. The superoxide anion binding site is located in a cleft close to the dimer interface. The coordination geometry of the Fe site is a distorted trigonal bipyramidal arrangement, whose axial ligands are His43 and a solvent molecule, and whose in-plane ligands are His95, Asp195, and His199. A comparison of the structural features of cowpea FeSOD with those of homologous SODs reveals subtle differences in regard to the metal–protein interactions, and confirms the existence of two regions that may control the traffic of substrate and product: one located near the Fe binding site, and another in the dimer interface. The evolutionary conservation of reciprocal interactions of both monomers in neighboring active sites suggests possible subunit cooperation during catalysis.

Keywords: antioxidants; iron superoxide dismutase; manganese superoxide dismutase; X-ray crystallography; protein–protein interaction

Abbreviations: SOD, superoxide dismutase • PDB, Protein Data Bank • RMS, root-mean-square • ROS, reactive oxygen species • T_m, transition temperature • CuZnSOD, copper zinc superoxide dismutase • FeSOD, iron superoxide dismutase • Vu_FeSOD, Vigna unguiculata iron superoxide dismutase • Ec_FeSOD, Escherichia coli iron superoxide dismutase • Po_FeSOD, Pseudomonas ovalis iron superoxide dismutase • Mt_FeSOD, Methanobacterium thermoautotrophicum iron superoxide dismutase • Ss_FeSOD, Sulfolobus solfataricus iron superoxide dismutase • MnSOD, manganese superoxide dismutase • Hu_MnSOD, Homo sapiens manganese superoxide dismutase • Ec_MnSOD, Escherichia coli manganese superoxide dismutase

Article and publication are at http://www.proteinscience.org/cgi/doi/10.1110/ps.04979505.

Reprint requests to: Guillermo Montoya, Structural Biology and Biocomputing Program, Spanish National Cancer Center (CNIO), Macromolecular Crystallography Group, c/o Melchor Fernández Almagro 3, 28029 Madrid, Spain; e-mail: gmontoya{at}cnio.es; fax: +00-34-912246976.

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?