Download MendeleyIron-Sulfur Cluster Binding by Mitochondrial Monothiol Glutaredoxin-1 of Trypanosoma brucei: Molecular Basis of Iron-Sulfur Cluster Coordination and Relevance for Parasite Infectivity.
Manta, B., Pavan, C., Sturlese, M., Medeiros, A., Crispo, M., Berndt, C., Krauth-Siegel, R.L., Bellanda, M., Comini, M.A.(2013) Antioxid Redox Signal 19: 665-682
- PubMed: 23259530
- DOI: https://doi.org/10.1089/ars.2012.4859
- Primary Citation of Related Structures:
2LTK - PubMed Abstract:
Monothiol glutaredoxins (1-C-Grxs) are small proteins linked to the cellular iron and redox metabolism. Trypanosoma brucei brucei, model organism for human African trypanosomiasis, expresses three 1-C-Grxs. 1-C-Grx1 is a highly abundant mitochondrial protein capable to bind an iron-sulfur cluster (ISC) in vitro using glutathione (GSH) as cofactor. We here report on the functional and structural analysis of 1-C-Grx1 in relation to its ISC-binding properties. An N-terminal extension unique to 1-C-Grx1 from trypanosomatids affects the oligomeric structure and the ISC-binding capacity of the protein. The active-site Cys104 is essential for ISC binding, and the parasite-specific glutathionylspermidine and trypanothione can replace GSH as the ligands of the ISC. Interestingly, trypanothione forms stable protein-free ISC species that in vitro are incorporated into the dithiol T. brucei 2-C-Grx1, but not 1-C-Grx1. Overexpression of the C104S mutant of 1-C-Grx1 impairs disease progression in a mouse model. The structure of the Grx-domain of 1-C-Grx1 was solved by nuclear magnetic resonance spectroscopy. Despite the fact that several residues--which in other 1-C-Grxs are involved in the noncovalent binding of GSH--are conserved, different physicochemical approaches did not reveal any specific interaction between 1-C-Grx1 and free thiol ligands. Parasite Grxs are able to coordinate an ISC formed with trypanothione, suggesting a new mechanism of ISC binding and a novel function for the parasite-specific dithiol. The first 3D structure and in vivo relevance of a 1-C-Grx from a pathogenic protozoan are reported. T. brucei 1-C-Grx1 is indispensable for mammalian parasitism and utilizes a new mechanism for ISC binding.
Organizational Affiliation:
Laboratory Redox Biology of Trypanosomes, Institut Pasteur de Montevideo, Montevideo, Uruguay.
