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Abstract
Iron–sulfur (Fe–S) clusters are protein cofactors of a multitude of enzymes performing essential biological functions. Specialized multi-protein machineries present in all types of organisms support their biosynthesis. These machineries encompass a scaffold protein on which Fe–S clusters are assembled and a cysteine desulfurase that provides sulfur in the form of a persulfide. The sulfide ions are produced by reductive cleavage of the persulfide, which involves specific reductase systems. Several other components are required for Fe–S biosynthesis, including frataxin, a key protein of controversial function and accessory components for insertion of Fe–S clusters in client proteins. Fe–S cluster biosynthesis is thought to rely on concerted and carefully orchestrated processes. However, the elucidation of the mechanisms of their assembly has remained a challenging task due to the biochemical versatility of iron and sulfur and the relative instability of Fe–S clusters. Nonetheless, significant progresses have been achieved in the past years, using biochemical, spectroscopic and structural approaches with reconstituted system in vitro. In this paper, we review the most recent advances on the mechanism of assembly for the founding member of the Fe–S cluster family, the [2Fe2S] cluster that is the building block of all other Fe–S clusters. The aim is to provide a survey of the mechanisms of iron and sulfur insertion in the scaffold proteins by examining how these processes are coordinated, how sulfide is produced and how the dinuclear [2Fe2S] cluster is formed, keeping in mind the question of the physiological relevance of the reconstituted systems. We also cover the latest outcomes on the functional role of the controversial frataxin protein in Fe–S cluster biosynthesis.
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Herrera MG, Noguera ME, Sewell KE, Agudelo Suárez WA, Capece L, Klinke S, Santos J. Structure of the Human ACP-ISD11 Heterodimer. Biochemistry 2019; 58:4596-4609. [PMID: 31664822 DOI: 10.1021/acs.biochem.9b00539] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In recent years, the mammalian mitochondrial protein complex for iron-sulfur cluster assembly has been the focus of important studies. This is partly because of its high degree of relevance in cell metabolism and because mutations of the involved proteins are the cause of several human diseases. Cysteine desulfurase NFS1 is the key enzyme of the complex. At present, it is well-known that the active form of NFS1 is stabilized by the small protein ISD11. In this work, the structure of the human mitochondrial ACP-ISD11 heterodimer was determined at 2.0 Å resolution. ACP-ISD11 forms a cooperative unit stabilized by several ionic interactions, hydrogen bonds, and apolar interactions. The 4'-phosphopantetheine-acyl chain, which is covalently bound to ACP, interacts with several residues of ISD11, modulating together with ACP the foldability of ISD11. Recombinant human ACP-ISD11 was able to interact with the NFS1 desulfurase, thus yielding an active enzyme, and the NFS1/ACP-ISD11 core complex was activated by frataxin and ISCU proteins. Internal motions of ACP-ISD11 were studied by molecular dynamics simulations, showing the persistence of the interactions between both protein chains. The conformation of the dimer is similar to that found in the context of the (NFS1/ACP-ISD11)2 supercomplex core, which contains the Escherichia coli ACP instead of the human variant. This fact suggests a sequential mechanism for supercomplex consolidation, in which the ACP-ISD11 complex may fold independently and, after that, the NFS1 dimer would be stabilized.
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Affiliation(s)
- María Georgina Herrera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Intendente Güiraldes 2160-Ciudad Universitaria , C1428EGA Buenos Aires , Argentina
| | - Martín Ezequiel Noguera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Intendente Güiraldes 2160-Ciudad Universitaria , C1428EGA Buenos Aires , Argentina.,Instituto de Química y Fisicoquímica Biológicas , Dr. Alejandro Paladini, Universidad de Buenos Aires, CONICET , Junín 956 , C1113AAD Buenos Aires , Argentina
| | - Karl Ellioth Sewell
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Intendente Güiraldes 2160-Ciudad Universitaria , C1428EGA Buenos Aires , Argentina
| | - William Armando Agudelo Suárez
- Fundación Instituto de Inmunología de Colombia (FIDIC) , Av. 50 No. 26-20 , Bogotá D.C. , Colombia.,Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires, Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE CONICET) , C1428EGA Buenos Aires , Argentina
| | - Luciana Capece
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires, Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE CONICET) , C1428EGA Buenos Aires , Argentina
| | - Sebastián Klinke
- Fundación Instituto Leloir , IIBBA-CONICET, and Plataforma Argentina de Biología Estructural y Metabolómica PLABEM , Av. Patricias Argentinas 435 , C1405BWE Buenos Aires , Argentina
| | - Javier Santos
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Intendente Güiraldes 2160-Ciudad Universitaria , C1428EGA Buenos Aires , Argentina
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