Biochemistry of copper site assembly in heme-copper oxidases: a theme with variations

Copper is an essential cofactor for aerobic respiration, since it is required as a redox cofactor in Cytochrome c Oxidase (COX). This ancient and highly conserved enzymatic complex from the family of heme-copper oxidase possesses two copper sites: CuA and CuB. Biosynthesis of the oxidase is a complex, stepwise process that requires a high number of assembly factors. In this review, we summarize the state-of-the-art in the assembly of COX, with special emphasis in the assembly of copper sites. Assembly of the CuA site is better understood, being at the same time highly variable among organisms. We also discuss the current challenges that prevent the full comprehension of the mechanisms of assembly and the pending issues in the field.Para citar este articulo: Llases, M.-E.; Morgada, M.N.; Vila, A.J. Biochemistry of Copper Site Assembly in Heme-Copper Oxidases: A Theme with Variations. Int. J. Mol. Sci. 2019, 20, 3830. https://doi.org/10.3390/ijms20153830Fil: Lllases, María Eugenia. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario (IBR -CONICET); Argentina.Fil: Morgada, Marcos N. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario (IBR -CONICET); Argentina.Fil: Morgada, Marcos N. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Biológica. Área Biofísica; Argentina.Fil: Vila, Alejandro J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario (IBR -CONICET); Argentina.Fil: Vila, Alejandro J. Plataforma de Biología Estructural y Metabolómica (PLABEM); Argentina.Fil: Vila, Alejandro J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Biológica. Área Biofísica; Argentina

CuA-based chimeric T1 copper sites allow for independent modulation of reorganization energy and reduction potential

Attaining rational modulation of thermodynamic and kinetic redox parameters of metalloproteins is a key milestone towards the (re)design of proteins with new or improved redox functions. Here we report that implantation of ligand loops from natural T1 proteins into the scaffold of a CuA protein leads to a series of distorted T1-like sites that allow for independent modulation of reduction potentials (E°´) and electron transfer reorganization energies (l). On the one hand E°´ values could be fine-tuned over 120 mV without affecting l. On the other, l values could be modulated by more than a factor of two while affecting E°´ only by a few millivolts. These results are in sharp contrast to previous studies that used T1 cupredoxin folds, thus highlighting the importance of the protein scaffold in determining such parametersPara citar este articulo: Chem. Sci., 2020, 11, 6193Fil: Szuster, Jonathan. Universidad de Buenos Aires. Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE -CONICET); Argentina.Fil: Szuster, Jonathan. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina.Fil: Zitare, Ulises A. Universidad de Buenos Aires. Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE -CONICET); Argentina.Fil: Zitare, Ulises A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina.Fil: Castro, María A. Universidad de Buenos Aires. Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE -CONICET); Argentina.Fil: Castro, María A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina.Fil: Leguto, Alcides J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario (IBR -CONICET); Argentina.Fil: Leguto, Alcides J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Biológica; Argentina.Fil: Morgada, Marcos N. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario (IBR -CONICET); Argentina.Fil: Morgada, Marcos N. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Biológica; Argentina.Fil: Vila, Alejandro J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario (IBR -CONICET); Argentina.Fil: Vila, Alejandro J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Biológica; Argentina.Fil: Murgida, Daniel H. Universidad de Buenos Aires. Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE -CONICET); Argentina.Fil: Murgida, Daniel H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentina

Unexpected Electron Spin Density on the Axial Methionine Ligand in CuA Suggests Its Involvement in Electron Pathways

The CuA center is a paradigm for the study of long-range biological electron transfer. This metal center is an essential cofactor for terminal oxidases like Cytochrome c oxidase, the enzymatic complex responsible for cellular respiration in eukaryotes and in most bacteria. CuA acts as an electron hub by transferring electrons from reduced cytochrome c to the catalytic site of the enzyme where dioxygen reduction takes place. Different electron transfer pathways have been proposed involving a weak axial methionine ligand residue, conserved in all CuA sites. This hypothesis has been challenged by theoretical calculations indicating the lack of electron spin density in this ligand. Here we report an NMR study with selectively labeled methionine in a native CuA. NMR spectroscopy discloses the presence of net electron spin density in the methionine axial ligand in the two alternative ground states of this metal center. Similar spin delocalization observed on two second sphere mutants further supports this evidence. These data provide a novel view of the electronic structure of CuA centers and support previously neglected electron transfer pathways. </p

COA6 is structurally tuned to function as a thiol-disulfide oxidoreductase in copper delivery to mitochondrial cytochrome c oxidase

In eukaryotes, cellular respiration is driven by mitochondrial cytochrome c oxidase (CcO), an enzyme complex that requires copper cofactors for its catalytic activity. Insertion of copper into its catalytically active subunits, including COX2, is a complex process that requires metallochaperones and redox proteins including SCO1, SCO2, and COA6, a recently discovered protein whose molecular function is unknown. To uncover the molecular mechanism by which COA6 and SCO proteins mediate copper delivery to COX2, we have solved the solution structure of COA6, which reveals a coiled-coil-helix-coiled-coilhelix domain typical of redox-active proteins found in the mitochondrial inter-membrane space. Accordingly, we demonstrate that COA6 can reduce the copper-coordinating disulfides of its client proteins, SCO1 and COX2, allowing for copper binding. Finally, our determination of the interaction surfaces and reduction potentials of COA6 and its client proteins provides a mechanism of how metallochaperone and disulfide reductase activities are coordinated to deliver copper to CcO.Fil: Soma, Shivatheja. Texas A&M University. Department of Biochemistry and Biophysics; United States.Fil: Morgada, Marcos N. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario (IBR -CONICET); Argentina.Fil: Morgada, Marcos N. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Biológica. Área Biofísica; Argentina.Fil: Naik, Mandar T. Texas A&M University. Department of Biochemistry and Biophysics; United States.Fil: Naik, Mandar T. Brown University. Department of Molecular Pharmacology, Physiology, and Biotechnology; United States.Fil: Boulet, Aren. University of Saskatchewan. Department of Biochemistry, Microbiology and Immunology; Canada.Fil: Roesler, Anna A. University of Saskatchewan. Department of Biochemistry, Microbiology and Immunology; Canada.Fil: Dziuba, Nathaniel. Texas A&M University. Department of Biochemistry and Biophysics; United States.Fil: Ghosh, Alok. Texas A&M University. Department of Biochemistry and Biophysics; United States.Fil: Ghosh, Alok. University of Calcutta. Department of Biochemistry; India.Fil: Yu, Qinhong. University of California. Department of Chemistry; United States.Fil: Lindahl, Paul A. Texas A&M University. Department of Biochemistry and Biophysics; United States.Fil: Lindahl, Paul A. Texas A&M University. Department of Chemistry; United States.Fil: Ames, James B. University of California. Department of Chemistry; United States.Fil: Leary, Scot C. University of Saskatchewan. Department of Biochemistry, Microbiology and Immunology; Canada.Fil: Vila, Alejandro J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario (IBR -CONICET); Argentina.Fil: Vila, Alejandro J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Biológica. Área Biofísica; Argentina.Fil: Gohil, Vishal M. Texas A&M University. Department of Biochemistry and Biophysics; United States

pH-induced binding of the axial ligand in an engineered CuA site favors the πu state

CuA centers perform efficient long-range electron transfer. The electronic structure of native CuA sites can be described by a double-potential well with a dominant σu∗ ground state in fast equilibrium with a less populated πu ground state. Here, we report a CuA mutant in which a lysine was introduced in the axial position. This results in a highly unstable protein with a pH-dependent population of the two ground states. Deep analysis of the high-pH form of this variant shows the stabilization of the πu ground state due to direct binding of the Lys residue to the copper center that we attribute to deprotonation of this residue.Fil: Morgada, Marcos Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Emiliani, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Chacón, Kelly N.. Oregon Health and Sciences University; Estados UnidosFil: Álvarez Paggi, Damián Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Murgida, Daniel Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Blackburn, Ninian J.. Oregon Health And Science University; Estados UnidosFil: Abriata, Luciano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Vila, Alejandro Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin