4DVH

Crystal structure of Trypanosoma cruzi mitochondrial iron superoxide dismutase

Summary for 4DVH

• Entry DOI: 10.2210/pdb4dvh/pdb
• Descriptor: Superoxide dismutase, FE (III) ION (3 entities in total)
• Functional Keywords: iron superoxide dismutase, mitochondrial, oxidoreductase
• Biological source: Trypanosoma cruzi
• Total number of polymer chains: 2
• Total formula weight: 47337.08

Authors

Larrieux, N.,Buschiazzo, A. (deposition date: 2012-02-23, release date: 2013-03-27, Last modification date: 2023-09-13)

Primary citation

Martinez, A.,Peluffo, G.,Petruk, A.A.,Hugo, M.,Pineyro, D.,Demicheli, V.,Moreno, D.M.,Lima, A.,Batthyany, C.,Duran, R.,Robello, C.,Marti, M.A.,Larrieux, N.,Buschiazzo, A.,Trujillo, M.,Radi, R.,Piacenza, L.
Structural and Molecular Basis of the Peroxynitrite-mediated Nitration and Inactivation of Trypanosoma cruzi Iron-Superoxide Dismutases (Fe-SODs) A and B: DISPARATE SUSCEPTIBILITIES DUE TO THE REPAIR OF TYR35 RADICAL BY CYS83 IN Fe-SODB THROUGH INTRAMOLECULAR ELECTRON TRANSFER.
J.Biol.Chem., 289:12760-12778, 2014

PubMed Abstract: Trypanosoma cruzi, the causative agent of Chagas disease, contains exclusively iron-dependent superoxide dismutases (Fe-SODs) located in different subcellular compartments. Peroxynitrite, a key cytotoxic and oxidizing effector biomolecule, reacted with T. cruzi mitochondrial (Fe-SODA) and cytosolic (Fe-SODB) SODs with second order rate constants of 4.6 ± 0.2 × 10(4) M(-1) s(-1) and 4.3 ± 0.4 × 10(4) M(-1) s(-1) at pH 7.4 and 37 °C, respectively. Both isoforms are dose-dependently nitrated and inactivated by peroxynitrite. Susceptibility of T. cruzi Fe-SODA toward peroxynitrite was similar to that reported previously for Escherichia coli Mn- and Fe-SODs and mammalian Mn-SOD, whereas Fe-SODB was exceptionally resistant to oxidant-mediated inactivation. We report mass spectrometry analysis indicating that peroxynitrite-mediated inactivation of T. cruzi Fe-SODs is due to the site-specific nitration of the critical and universally conserved Tyr(35). Searching for structural differences, the crystal structure of Fe-SODA was solved at 2.2 Å resolution. Structural analysis comparing both Fe-SOD isoforms reveals differences in key cysteines and tryptophan residues. Thiol alkylation of Fe-SODB cysteines made the enzyme more susceptible to peroxynitrite. In particular, Cys(83) mutation (C83S, absent in Fe-SODA) increased the Fe-SODB sensitivity toward peroxynitrite. Molecular dynamics, electron paramagnetic resonance, and immunospin trapping analysis revealed that Cys(83) present in Fe-SODB acts as an electron donor that repairs Tyr(35) radical via intramolecular electron transfer, preventing peroxynitrite-dependent nitration and consequent inactivation of Fe-SODB. Parasites exposed to exogenous or endogenous sources of peroxynitrite resulted in nitration and inactivation of Fe-SODA but not Fe-SODB, suggesting that these enzymes play distinctive biological roles during parasite infection of mammalian cells.

PubMed: 24616096
DOI: 10.1074/jbc.M113.545590

Experimental method

X-RAY DIFFRACTION (2.23 Å)