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Roland Lill - One of the best experts on this subject based on the ideXlab platform.
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biochemical reconstitution and spectroscopic analysis of iron sulfur Proteins
Methods in Enzymology, 2018Co-Authors: Svenandreas Freibert, Antonio J Pierik, Benjamin D Weiler, Ulrich Mühlenhoff, Eckhard Bill, Roland LillAbstract:Iron-Sulfur (Fe/S) Proteins are involved in numerous key biological functions such as respiration, metabolic processes, protein translation, DNA synthesis, and DNA repair. The simplest types of Fe/S clusters include [2Fe-2S], [3Fe-4S], and [4Fe-4S] forms that sometimes are present in multiple copies. De novo assembly of Fe/S cofactors and their insertion into apoProteins in living cells requires complex proteinaceous machineries that are frequently highly conserved. In eukaryotes such as yeast and mammals, the mitochondrial Iron-Sulfur cluster assembly machinery and the cytosolic Iron-Sulfur protein assembly system consist of more than 30 components that cooperate in the generation of some 50 cellular Fe/S Proteins. Both the mechanistic dissection of the intracellular Fe/S protein assembly pathways and the identification and characterization of Fe/S Proteins rely on tool boxes of in vitro and in vivo methods. These cell biological, biochemical, and biophysical techniques help to determine the extent, stability, and type of bound Fe/S cluster. They also serve to distinguish bona fide Fe/S Proteins from other metal-binding Proteins containing similar cofactor coordination motifs. Here, we present a collection of in vitro methods that have proven useful for basic biochemical and biophysical characterization of Fe/S Proteins. First, we describe the chemical assembly of [2Fe-2S] or [4Fe-4S] clusters on purified apoProteins. Then, we summarize a reconstitution system reproducing the de novo synthesis of a [2Fe-2S] cluster in mitochondria. Finally, we explain the use of UV-vis, CD, electron paramagnetic resonance, and Mossbauer spectroscopy for the routine characterization of Fe/S Proteins.
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Mitochondrial Bol1 and Bol3 function as assembly factors for specific Iron-Sulfur Proteins
eLife, 2016Co-Authors: Marta A. Uzarska, Veronica Nasta, Benjamin D Weiler, Farah Spantgar, Simone Ciofi-baffoni, Maria Rosaria Saviello, Leonardo Gonnelli, Ulrich Mühlenhoff, Lucia Banci, Roland LillAbstract:Proteins perform almost all the tasks necessary for cells to survive. However, some Proteins, especially enzymes involved in metabolism and energy production, need to contain extra molecules called co-factors to work properly. In human, yeast and other eukaryotic cells, co-factors called Iron-Sulfur clusters are made in compartments called mitochondria before being packaged into target Proteins. Defects that affect the assembly of Proteins with Iron-Sulfur clusters are associated with severe diseases that affect metabolism, the nervous system and the blood. Mitochondria contain at least 17 Proteins involved in making Iron-Sulfur Proteins, but there may be others that have not yet been identified. For example, a study on patients with a rare human genetic disease suggested that a protein called BOLA3 might also play a role in this process. BOLA3 is closely related to the BOLA1 Proteins. Here, Uzarska, Nasta, Weiler et al. used yeast to test how these Proteins contribute to the assembly of Iron-Sulfur Proteins. Biochemical techniques showed that the yeast equivalents of BOLA1 and BOLA3 (known as Bol1 and Bol3) play specific roles in the assembly pathway. When both of these Proteins were missing from yeast, some Iron-Sulfur Proteins – including an important enzyme called lipoic acid synthase – did not assemble properly. The experiments suggest that yeast Bol1 and Bol3 play overlapping and critical roles during the last step of Iron-Sulfur protein assembly when the Iron-Sulfur cluster is inserted into the target protein. Lastly, Uzarska, Nasta, Weiler et al. used biophysical techniques to show how Bol1 and Bol3 interact with another mitochondrial protein that performs a more general role in Iron-Sulfur protein assembly. Defects in assembling Iron-Sulfur Proteins are generally more harmful to human cells than yeast cells. Therefore, the next step is to investigate what exact roles BOLA1 and BOLA3 play in human cells and how similar this pathway is in different eukaryotes.
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The mitochondrial monothiol glutaredoxin S15 is essential for Iron-Sulfur protein maturation in Arabidopsis thaliana
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Anna Moseler, Roland Lill, Ulrich Mühlenhoff, Jonathan Przybyla-toscano, Nicolas Rouhier, Isabel Aller, Stephan Wagner, Thomas Nietzel, Carsten Berndt, Markus SchwarzlanderAbstract:The Iron-Sulfur cluster (ISC) is an ancient and essential cofactor of many Proteins involved in electron transfer and metabolic reactions. In Arabidopsis, three pathways exist for the maturation of Iron-Sulfur Proteins in the cytosol, plastids, and mitochondria. We functionally characterized the role of mitochondrial glutaredoxin S15 (GRXS15) in biogenesis of ISC containing aconitase through a combination of genetic, physiological, and biochemical approaches. Two Arabidopsis T-DNA insertion mutants were identified as null mutants with early embryonic lethal phenotypes that could be rescued by GRXS15. Furthermore, we showed that recombinant GRXS15 is able to coordinate and transfer an ISC and that this coordination depends on reduced glutathione (GSH). We found the Arabidopsis GRXS15 able to complement growth defects based on disturbed ISC protein assembly of a yeast Delta grx5 mutant. Modeling of GRXS15 onto the crystal structures of related nonplant Proteins highlighted amino acid residues that after mutation diminished GSH and subsequently ISC coordination, as well as the ability to rescue the yeast mutant. When used for plant complementation, one of these mutant variants, GRXS15(K83/A), led to severe developmental delay and a pronounced decrease in aconitase activity by approximately 65%. These results indicate that mitochondrial GRXS15 is an essential protein in Arabidopsis, required for full activity of Iron-Sulfur Proteins.
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maturation of cytosolic and nuclear iron sulfur Proteins
Trends in Cell Biology, 2014Co-Authors: Daili J A Netz, Judita Mascarenhas, Oliver Stehling, Roland Lill, Antonio J PierikAbstract:Eukaryotic cells contain numerous cytosolic and nuclear iron–sulfur (Fe/S) Proteins that perform key functions in metabolic catalysis, iron regulation, protein translation, DNA synthesis, and DNA repair. Synthesis of Fe/S clusters and their insertion into apoProteins are essential for viability and are conserved in eukaryotes. The process is catalyzed in two major steps by the CIA (cytosolic iron–sulfur protein assembly) machinery encompassing nine known Proteins. First, a [4Fe–4S] cluster is assembled on a scaffold complex. This step requires a sulfur-containing compound from mitochondria and reducing equivalents from an electron transfer chain. Second, the Fe/S cluster is transferred from the scaffold to specific apoProteins by the CIA targeting complex. This review summarizes our molecular knowledge on CIA protein function during the assembly process.
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The role of mitochondria in cytosolic-nuclear iron–sulfur protein biogenesis and in cellular iron regulation.
Current Opinion in Microbiology, 2014Co-Authors: Roland Lill, Vasundara Srinivasan, Ulrich MühlenhoffAbstract:Mitochondria are indispensable in eukaryotes because of their function in the maturation of cytosolic and nuclear iron–sulfur Proteins that are essential for DNA synthesis and repair, tRNA modification, and protein translation. The mitochondrial Fe/S cluster assembly machinery not only generates the organelle's iron–sulfur Proteins, but also extra-mitochondrial ones. Biogenesis of the latter Proteins requires the mitochondrial ABC transporter Atm1 that exports a sulfur-containing compound in a glutathione-dependent fashion. The process is further assisted by the cytosolic iron–sulfur protein assembly machinery. Here, we discuss the knowns and unknowns of the mitochondrial export process that is also crucial for signaling the cellular iron status to the regulatory systems involved in the maintenance of cellular iron homeostasis.
Ulrich Mühlenhoff - One of the best experts on this subject based on the ideXlab platform.
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biochemical reconstitution and spectroscopic analysis of iron sulfur Proteins
Methods in Enzymology, 2018Co-Authors: Svenandreas Freibert, Antonio J Pierik, Benjamin D Weiler, Ulrich Mühlenhoff, Eckhard Bill, Roland LillAbstract:Iron-Sulfur (Fe/S) Proteins are involved in numerous key biological functions such as respiration, metabolic processes, protein translation, DNA synthesis, and DNA repair. The simplest types of Fe/S clusters include [2Fe-2S], [3Fe-4S], and [4Fe-4S] forms that sometimes are present in multiple copies. De novo assembly of Fe/S cofactors and their insertion into apoProteins in living cells requires complex proteinaceous machineries that are frequently highly conserved. In eukaryotes such as yeast and mammals, the mitochondrial Iron-Sulfur cluster assembly machinery and the cytosolic Iron-Sulfur protein assembly system consist of more than 30 components that cooperate in the generation of some 50 cellular Fe/S Proteins. Both the mechanistic dissection of the intracellular Fe/S protein assembly pathways and the identification and characterization of Fe/S Proteins rely on tool boxes of in vitro and in vivo methods. These cell biological, biochemical, and biophysical techniques help to determine the extent, stability, and type of bound Fe/S cluster. They also serve to distinguish bona fide Fe/S Proteins from other metal-binding Proteins containing similar cofactor coordination motifs. Here, we present a collection of in vitro methods that have proven useful for basic biochemical and biophysical characterization of Fe/S Proteins. First, we describe the chemical assembly of [2Fe-2S] or [4Fe-4S] clusters on purified apoProteins. Then, we summarize a reconstitution system reproducing the de novo synthesis of a [2Fe-2S] cluster in mitochondria. Finally, we explain the use of UV-vis, CD, electron paramagnetic resonance, and Mossbauer spectroscopy for the routine characterization of Fe/S Proteins.
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Mitochondrial Bol1 and Bol3 function as assembly factors for specific Iron-Sulfur Proteins
eLife, 2016Co-Authors: Marta A. Uzarska, Veronica Nasta, Benjamin D Weiler, Farah Spantgar, Simone Ciofi-baffoni, Maria Rosaria Saviello, Leonardo Gonnelli, Ulrich Mühlenhoff, Lucia Banci, Roland LillAbstract:Proteins perform almost all the tasks necessary for cells to survive. However, some Proteins, especially enzymes involved in metabolism and energy production, need to contain extra molecules called co-factors to work properly. In human, yeast and other eukaryotic cells, co-factors called Iron-Sulfur clusters are made in compartments called mitochondria before being packaged into target Proteins. Defects that affect the assembly of Proteins with Iron-Sulfur clusters are associated with severe diseases that affect metabolism, the nervous system and the blood. Mitochondria contain at least 17 Proteins involved in making Iron-Sulfur Proteins, but there may be others that have not yet been identified. For example, a study on patients with a rare human genetic disease suggested that a protein called BOLA3 might also play a role in this process. BOLA3 is closely related to the BOLA1 Proteins. Here, Uzarska, Nasta, Weiler et al. used yeast to test how these Proteins contribute to the assembly of Iron-Sulfur Proteins. Biochemical techniques showed that the yeast equivalents of BOLA1 and BOLA3 (known as Bol1 and Bol3) play specific roles in the assembly pathway. When both of these Proteins were missing from yeast, some Iron-Sulfur Proteins – including an important enzyme called lipoic acid synthase – did not assemble properly. The experiments suggest that yeast Bol1 and Bol3 play overlapping and critical roles during the last step of Iron-Sulfur protein assembly when the Iron-Sulfur cluster is inserted into the target protein. Lastly, Uzarska, Nasta, Weiler et al. used biophysical techniques to show how Bol1 and Bol3 interact with another mitochondrial protein that performs a more general role in Iron-Sulfur protein assembly. Defects in assembling Iron-Sulfur Proteins are generally more harmful to human cells than yeast cells. Therefore, the next step is to investigate what exact roles BOLA1 and BOLA3 play in human cells and how similar this pathway is in different eukaryotes.
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The mitochondrial monothiol glutaredoxin S15 is essential for Iron-Sulfur protein maturation in Arabidopsis thaliana
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Anna Moseler, Roland Lill, Ulrich Mühlenhoff, Jonathan Przybyla-toscano, Nicolas Rouhier, Isabel Aller, Stephan Wagner, Thomas Nietzel, Carsten Berndt, Markus SchwarzlanderAbstract:The Iron-Sulfur cluster (ISC) is an ancient and essential cofactor of many Proteins involved in electron transfer and metabolic reactions. In Arabidopsis, three pathways exist for the maturation of Iron-Sulfur Proteins in the cytosol, plastids, and mitochondria. We functionally characterized the role of mitochondrial glutaredoxin S15 (GRXS15) in biogenesis of ISC containing aconitase through a combination of genetic, physiological, and biochemical approaches. Two Arabidopsis T-DNA insertion mutants were identified as null mutants with early embryonic lethal phenotypes that could be rescued by GRXS15. Furthermore, we showed that recombinant GRXS15 is able to coordinate and transfer an ISC and that this coordination depends on reduced glutathione (GSH). We found the Arabidopsis GRXS15 able to complement growth defects based on disturbed ISC protein assembly of a yeast Delta grx5 mutant. Modeling of GRXS15 onto the crystal structures of related nonplant Proteins highlighted amino acid residues that after mutation diminished GSH and subsequently ISC coordination, as well as the ability to rescue the yeast mutant. When used for plant complementation, one of these mutant variants, GRXS15(K83/A), led to severe developmental delay and a pronounced decrease in aconitase activity by approximately 65%. These results indicate that mitochondrial GRXS15 is an essential protein in Arabidopsis, required for full activity of Iron-Sulfur Proteins.
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The role of mitochondria in cytosolic-nuclear iron–sulfur protein biogenesis and in cellular iron regulation.
Current Opinion in Microbiology, 2014Co-Authors: Roland Lill, Vasundara Srinivasan, Ulrich MühlenhoffAbstract:Mitochondria are indispensable in eukaryotes because of their function in the maturation of cytosolic and nuclear iron–sulfur Proteins that are essential for DNA synthesis and repair, tRNA modification, and protein translation. The mitochondrial Fe/S cluster assembly machinery not only generates the organelle's iron–sulfur Proteins, but also extra-mitochondrial ones. Biogenesis of the latter Proteins requires the mitochondrial ABC transporter Atm1 that exports a sulfur-containing compound in a glutathione-dependent fashion. The process is further assisted by the cytosolic iron–sulfur protein assembly machinery. Here, we discuss the knowns and unknowns of the mitochondrial export process that is also crucial for signaling the cellular iron status to the regulatory systems involved in the maintenance of cellular iron homeostasis.
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maturation of iron sulfur Proteins in eukaryotes mechanisms connected processes and diseases
Annual Review of Biochemistry, 2008Co-Authors: Roland Lill, Ulrich MühlenhoffAbstract:Iron-Sulfur (Fe/S) Proteins are involved in a wide variety of cellular processes such as enzymatic reactions, respiration, cofactor biosynthesis, ribosome biogenesis, regulation of gene expression, and DNA-RNA metabolism. Assembly of Fe/S clusters, small inorganic cofactors, is assisted by complex proteinaceous machineries, which use cysteine as a source of sulfur, combine it with iron to synthesize an Fe/S cluster on scaffold Proteins, and finally incorporate the cluster into recipient apoProteins. In eukaryotes, such as yeast and human cells, more than 20 components are known that facilitate the maturation of Fe/S Proteins in mitochondria, cytosol, and nucleus. These biogenesis components also perform crucial roles in other cellular pathways, e.g., in the regulation of iron homeostasis or the modification of tRNA. Numerous diseases including several neurodegenerative and hematological disorders have been associated with defects in Fe/S protein biogenesis, underlining the central importance of this proce...
Nicolas Rouhier - One of the best experts on this subject based on the ideXlab platform.
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Roles and maturation of iron–sulfur Proteins in plastids
JBIC Journal of Biological Inorganic Chemistry, 2018Co-Authors: Jonathan Przybyla-toscano, Mélanie Roland, Frédéric Gaymard, Jérémy Couturier, Nicolas RouhierAbstract:One reason why iron is an essential element for most organisms is its presence in prosthetic groups such as hemes or iron–sulfur (Fe–S) clusters, which are notably required for electron transfer reactions. As an organelle with an intense metabolism in plants, chloroplast relies on many Fe–S Proteins. This includes those present in the electron transfer chain which will be, in fact, essential for most other metabolic processes occurring in chloroplasts, e.g., carbon fixation, nitrogen and sulfur assimilation, pigment, amino acid, and vitamin biosynthetic pathways to cite only a few examples. The maturation of these Fe–S Proteins requires a complex and specific machinery named SUF (sulfur mobilisation). The assembly process can be split in two major steps, (1) the de novo assembly on scaffold Proteins which requires ATP, iron and sulfur atoms, electrons, and thus the concerted action of several Proteins forming early acting assembly complexes, and (2) the transfer of the preformed Fe–S cluster to client Proteins using a set of late-acting maturation factors. Similar machineries, having in common these basic principles, are present in the cytosol and in mitochondria. This review focuses on the currently known molecular details concerning the assembly and roles of Fe–S Proteins in plastids.
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roles and maturation of iron sulfur Proteins in plastids
Journal of Biological Inorganic Chemistry, 2018Co-Authors: Jonathan Przybylatoscano, Mélanie Roland, Frédéric Gaymard, Jérémy Couturier, Nicolas RouhierAbstract:One reason why iron is an essential element for most organisms is its presence in prosthetic groups such as hemes or iron–sulfur (Fe–S) clusters, which are notably required for electron transfer reactions. As an organelle with an intense metabolism in plants, chloroplast relies on many Fe–S Proteins. This includes those present in the electron transfer chain which will be, in fact, essential for most other metabolic processes occurring in chloroplasts, e.g., carbon fixation, nitrogen and sulfur assimilation, pigment, amino acid, and vitamin biosynthetic pathways to cite only a few examples. The maturation of these Fe–S Proteins requires a complex and specific machinery named SUF (sulfur mobilisation). The assembly process can be split in two major steps, (1) the de novo assembly on scaffold Proteins which requires ATP, iron and sulfur atoms, electrons, and thus the concerted action of several Proteins forming early acting assembly complexes, and (2) the transfer of the preformed Fe–S cluster to client Proteins using a set of late-acting maturation factors. Similar machineries, having in common these basic principles, are present in the cytosol and in mitochondria. This review focuses on the currently known molecular details concerning the assembly and roles of Fe–S Proteins in plastids.
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Involvement of Arabidopsis glutaredoxin S14 in the maintenance of chlorophyll content
Plant Cell and Environment, 2017Co-Authors: Pascal Rey, Noëlle Becuwe, Sébastien Tourrette, Nicolas RouhierAbstract:Plant class-II glutaredoxins (GRXs) are oxidoreductases carrying a CGFS active site signature and are able to bind Iron-Sulfur clusters invitro. In order to explore the physiological functions of the 2 plastidial class-II isoforms, GRXS14 and GRXS16, we generated knockdown and overexpression Arabidopsis thaliana lines and characterized their phenotypes using physiological and biochemical approaches. Plants deficient in one GRX did not display any growth defect, whereas the growth of plants lacking both was slowed. Plants overexpressing GRXS14 exhibited reduced chlorophyll content in control, high-light, and high-salt conditions. However, when exposed to prolonged darkness, plants lacking GRXS14 showed accelerated chlorophyll loss compared to wild-type and overexpression lines. We observed that the GRXS14 abundance and the proportion of reduced form were modified in wild type upon darkness and high salt. The dark treatment also resulted in decreased abundance of Proteins involved in the maturation of Iron-Sulfur Proteins. We propose that the phenotype of GRXS14-modified lines results from its participation in the control of chlorophyll content in relation with light and osmotic conditions, possibly through a dual action in regulating the redox status of biosynthetic enzymes and contributing to the biogenesis of Iron-Sulfur clusters, which are essential cofactors in chlorophyll metabolism. In this work, we aimed at characterizing the physiological functions of the plastidial class-II glutaredoxins (GRXs), GRXS14 and GRXS16, two oxidoreductases able to bind Iron-Sulfur clusters in vitro. We observed that plants deficient in a single GRX do not display any growth defect, whereas the growth of plants lacking both was slowed. Plants overexpressing GRXS14 exhibited reduced chlorophyll content, whereas plants lacking GRXS14 showed accelerated chlorophyll loss upon prolonged darkness, a condition resulting in GRXS14 oxidation and in strong decreases in the abundance of Proteins involved in the maturation of Iron-Sulfur Proteins. Hence, GRXS14 would participate in chlorophyll maintenance by regulating the redox status of biosynthetic enzymes and/or the biogenesis of Iron-Sulfur Proteins involved in chlorophyll metabolism.
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The mitochondrial monothiol glutaredoxin S15 is essential for Iron-Sulfur protein maturation in Arabidopsis thaliana
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Anna Moseler, Roland Lill, Ulrich Mühlenhoff, Jonathan Przybyla-toscano, Nicolas Rouhier, Isabel Aller, Stephan Wagner, Thomas Nietzel, Carsten Berndt, Markus SchwarzlanderAbstract:The Iron-Sulfur cluster (ISC) is an ancient and essential cofactor of many Proteins involved in electron transfer and metabolic reactions. In Arabidopsis, three pathways exist for the maturation of Iron-Sulfur Proteins in the cytosol, plastids, and mitochondria. We functionally characterized the role of mitochondrial glutaredoxin S15 (GRXS15) in biogenesis of ISC containing aconitase through a combination of genetic, physiological, and biochemical approaches. Two Arabidopsis T-DNA insertion mutants were identified as null mutants with early embryonic lethal phenotypes that could be rescued by GRXS15. Furthermore, we showed that recombinant GRXS15 is able to coordinate and transfer an ISC and that this coordination depends on reduced glutathione (GSH). We found the Arabidopsis GRXS15 able to complement growth defects based on disturbed ISC protein assembly of a yeast Delta grx5 mutant. Modeling of GRXS15 onto the crystal structures of related nonplant Proteins highlighted amino acid residues that after mutation diminished GSH and subsequently ISC coordination, as well as the ability to rescue the yeast mutant. When used for plant complementation, one of these mutant variants, GRXS15(K83/A), led to severe developmental delay and a pronounced decrease in aconitase activity by approximately 65%. These results indicate that mitochondrial GRXS15 is an essential protein in Arabidopsis, required for full activity of Iron-Sulfur Proteins.
Maria J. Ramos - One of the best experts on this subject based on the ideXlab platform.
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parameters for molecular dynamics simulations of iron sulfur Proteins
Journal of Computational Chemistry, 2013Co-Authors: Alexandra T. P. Carvalho, Ana F. S. Teixeira, Maria J. RamosAbstract:Iron-Sulfur Proteins involved in electron transfer reactions have finely tuned redox potentials, which allow them to be highly efficient and specific. Factors such as metal center solvent exposure, interaction with charged residues, or hydrogen bonds between the ligand residues and amide backbone groups have all been pointed out to cause such specific redox potentials. Here, we derived parameters compatible with the AMBER force field for the metal centers of Iron-Sulfur Proteins and applied them in the molecular dynamics simulations of three Iron-Sulfur Proteins. We used density-functional theory (DFT) calculations and Seminario's method for the parameterization. Parameter validation was obtained by matching structures and normal frequencies at the quantum mechanics and molecular mechanics levels of theory. Having guaranteed a correct representation of the protein coordination spheres, the amide H-bonds and the water exposure to the ligands were analyzed. Our results for the pattern of interactions with the metal centers are consistent to those obtained by nuclear magnetic resonance spectroscopy (NMR) experiments and DFT calculations, allowing the application of molecular dynamics to the study of those Proteins. © 2013 Wiley Periodicals, Inc.
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Parameters for molecular dynamics simulations of iron‐sulfur Proteins
Journal of Computational Chemistry, 2013Co-Authors: Alexandra T. P. Carvalho, Ana F. S. Teixeira, Maria J. RamosAbstract:Iron-Sulfur Proteins involved in electron transfer reactions have finely tuned redox potentials, which allow them to be highly efficient and specific. Factors such as metal center solvent exposure, interaction with charged residues, or hydrogen bonds between the ligand residues and amide backbone groups have all been pointed out to cause such specific redox potentials. Here, we derived parameters compatible with the AMBER force field for the metal centers of Iron-Sulfur Proteins and applied them in the molecular dynamics simulations of three Iron-Sulfur Proteins. We used density-functional theory (DFT) calculations and Seminario's method for the parameterization. Parameter validation was obtained by matching structures and normal frequencies at the quantum mechanics and molecular mechanics levels of theory. Having guaranteed a correct representation of the protein coordination spheres, the amide H-bonds and the water exposure to the ligands were analyzed. Our results for the pattern of interactions with the metal centers are consistent to those obtained by nuclear magnetic resonance spectroscopy (NMR) experiments and DFT calculations, allowing the application of molecular dynamics to the study of those Proteins. © 2013 Wiley Periodicals, Inc.
Delmar S. Larsen - One of the best experts on this subject based on the ideXlab platform.
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cluster dependent charge transfer dynamics in iron sulfur Proteins
Biochemistry, 2018Co-Authors: Ziliang Mao, Shu-hao Liou, Nimesh Khadka, Francis E. Jenney, David B. Goodin, Lance C. Seefeldt, Michael W. W. Adams, Stephen P. Cramer, Delmar S. LarsenAbstract:Photoinduced charge-transfer dynamics and the influence of cluster size on the dynamics were investigated using five iron–sulfur clusters: the 1Fe–4S cluster in Pyrococcus furiosus rubredoxin, the 2Fe–2S cluster in Pseudomonas putida putidaredoxin, the 4Fe–4S cluster in nitrogenase iron protein, and the 8Fe–7S P-cluster and the 7Fe–9S–1Mo FeMo cofactor in nitrogenase MoFe protein. Laser excitation promotes the iron–sulfur clusters to excited electronic states that relax to lower states. The electronic relaxation lifetimes of the 1Fe–4S, 8Fe–7S, and 7Fe–9S–1Mo clusters are on the picosecond time scale, although the dynamics of the MoFe protein is a mixture of the dynamics of the latter two clusters. The lifetimes of the 2Fe–2S and 4Fe–4S clusters, however, extend to several nanoseconds. A competition between reorganization energies and the density of electronic states (thus electronic coupling between states) mediates the charge-transfer lifetimes, with the 2Fe–2S cluster of Pdx and the 4Fe–4S cluster of F...
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Cluster-Dependent Charge-Transfer Dynamics in Iron–Sulfur Proteins
2018Co-Authors: Ziliang Mao, Shu-hao Liou, Nimesh Khadka, Francis E. Jenney, David B. Goodin, Lance C. Seefeldt, Michael W. W. Adams, Stephen P. Cramer, Delmar S. LarsenAbstract:Photoinduced charge-transfer dynamics and the influence of cluster size on the dynamics were investigated using five iron–sulfur clusters: the 1Fe–4S cluster in Pyrococcus furiosus rubredoxin, the 2Fe–2S cluster in Pseudomonas putida putidaredoxin, the 4Fe–4S cluster in nitrogenase iron protein, and the 8Fe–7S P-cluster and the 7Fe–9S–1Mo FeMo cofactor in nitrogenase MoFe protein. Laser excitation promotes the iron–sulfur clusters to excited electronic states that relax to lower states. The electronic relaxation lifetimes of the 1Fe–4S, 8Fe–7S, and 7Fe–9S–1Mo clusters are on the picosecond time scale, although the dynamics of the MoFe protein is a mixture of the dynamics of the latter two clusters. The lifetimes of the 2Fe–2S and 4Fe–4S clusters, however, extend to several nanoseconds. A competition between reorganization energies and the density of electronic states (thus electronic coupling between states) mediates the charge-transfer lifetimes, with the 2Fe–2S cluster of Pdx and the 4Fe–4S cluster of Fe protein lying at the optimum leading to them having significantly longer lifetimes. Their long lifetimes make them the optimal candidates for long-range electron transfer and as external photosensitizers for other photoactivated chemical reactions like solar hydrogen production. Potential electron-transfer and hole-transfer pathways that possibly facilitate these charge transfers are proposed
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ultrafast charge transfer dynamics in the iron sulfur complex of rhodobacter capsulatus ferredoxin vi
Journal of Physical Chemistry Letters, 2017Co-Authors: Elizabeth C Carroll, Stephen P. Cramer, Delmar S. LarsenAbstract:Iron–sulfur Proteins play essential roles in various biological processes. Their electronic structure and vibrational dynamics are key to their rich chemistry but nontrivial to unravel. Here, the first ultrafast transient absorption and impulsive coherent vibrational spectroscopic (ICVS) studies on 2Fe–2S clusters in Rhodobacter capsulatus ferreodoxin VI are characterized. Photoexcitation initiated populations on multiple excited electronic states that evolve into each other in a long-lived charge-transfer state. This suggests a potential light-induced electron-transfer pathway as well as the possibility of using iron–sulfur Proteins as photosensitizers for light-dependent enzymes. A tyrosine chain near the active site suggests potential hole-transfer pathways and affirms this electron-transfer pathway. The ICVS data revealed vibrational bands at 417 and 484 cm–1, with the latter attributed to an excited-state mode. The temperature dependence of the ICVS modes suggests that the temperature effect on prote...
