The Experts below are selected from a list of 1317 Experts worldwide ranked by ideXlab platform

Toshiharu Hase - One of the best experts on this subject based on the ideXlab platform.

  • rational redesign of the Ferredoxin nadp oxido reductase Ferredoxin interaction for photosynthesis dependent h2 production
    Biochimica et Biophysica Acta, 2018
    Co-Authors: Katrin Wiegand, Toshiharu Hase, Martin Winkler, Sigrun Rumpel, Daniela Kannchen, Sascha Rexroth, Christophe Fares, Thomas Happe, Wolfgang Lubitz, Matthias Rogner
    Abstract:

    Utilization of electrons from the photosynthetic water splitting reaction for the generation of biofuels, commodities as well as application in biotransformations requires a partial rerouting of the photosynthetic electron transport chain. Due to its rather negative redox potential and its bifurcational function, Ferredoxin at the acceptor side of Photosystem 1 is one of the focal points for such an engineering. With hydrogen production as model system, we show here the impact and potential of redox partner design involving Ferredoxin (Fd), Ferredoxin-oxido-reductase (FNR) and [FeFe]‑hydrogenase HydA1 on electron transport in a future cyanobacterial design cell of Synechocystis PCC 6803. X-ray-structure-based rational design and the allocation of specific interaction residues by NMR-analysis led to the construction of Fd- and FNR-mutants, which in appropriate combination enabled an about 18-fold enhanced electron flow from Fd to HydA1 (in competition with equimolar amounts of FNR) in in vitro assays. The negative impact of these mutations on the Fd-FNR electron transport which indirectly facilitates H2 production (with a contribution of ≤42% by FNR variants and ≤23% by Fd-variants) and the direct positive impact on the Fd-HydA1 electron transport (≤23% by Fd-mutants) provide an excellent basis for the construction of a hydrogen-producing design cell and the study of photosynthetic efficiency-optimization with cyanobacteria.

  • structural basis for the isotype specific interactions of Ferredoxin and Ferredoxin nadp oxidoreductase an evolutionary switch between photosynthetic and heterotrophic assimilation
    Photosynthesis Research, 2017
    Co-Authors: Fumio Shinohara, Guy T. Hanke, Genji Kurisu, Toshiharu Hase, Yoko Kimataariga, Caroline G Bowsher
    Abstract:

    In higher plants, Ferredoxin (Fd) and Ferredoxin-NADP+ reductase (FNR) are each present as distinct isoproteins of photosynthetic type (leaf type) and non-photosynthetic type (root type). Root-type Fd and FNR are considered to facilitate the electron transfer from NADPH to Fd in the direction opposite to that occurring in the photosynthetic processes. We previously reported the crystal structure of the electron transfer complex between maize leaf FNR and Fd (leaf FNR:Fd complex), providing insights into the molecular interactions of the two proteins. Here we show the 2.49 A crystal structure of the maize root FNR:Fd complex, which reveals that the orientation of FNR and Fd remarkably varies from that of the leaf FNR:Fd complex, giving a structural basis for reversing the redox path. Root FNR was previously shown to interact preferentially with root Fd over leaf Fd, while leaf FNR retains similar affinity for these two types of Fds. The structural basis for such differential interaction was investigated using site-directed mutagenesis of the isotype-specific amino acid residues on the interface of Fd and FNR, based on the crystal structures of the FNR:Fd complexes from maize leaves and roots. Kinetic and physical binding analyses of the resulting mutants lead to the conclusion that the rearrangement of the charged amino acid residues on the Fd-binding surface of FNR confers isotype-specific interaction with Fd, which brings about the evolutional switch between photosynthetic and heterotrophic redox cascades.

  • investigation of protein protein interactions of Ferredoxin and sulfite reductase under different sodium chloride concentrations by nmr spectroscopy and isothermal titration calorimetry
    2015
    Co-Authors: Ju Yaen Kim, Toshiharu Hase, Takahisa Ikegami, Yuji Goto, Youngho Lee
    Abstract:

    Sulfite reductase (SiR) catalyzes the reduction of sulfite to sulfide by using six electrons transported from Ferredoxin (Fd) for eventual sulfur assimilation. As efficient electron flows are ensured by forming a productive Fd:SiR complex, detailed characterization of a Fd:SiR complex in solution is of particular importance. Here, we show that acidic residues of Fd play essential roles in forming an electron transfer complex with SiR by using attractive electrostatic interactions with putative basic residues of SiR. The thermodynamic approach using calorimetry revealed a favorable electrostatic contribution to form the Fd:SiR complex at the molecular level. Solution-state nuclear magnetic resonance (NMR) spectroscopy on 15N-labeled Fd in the presence of SiR showed large perturbations in NMR signals of acidic residues of Fd. The addition of NaCl diminished overall perturbations of NMR signals of SiR-bound Fd which resulted from the decrease in interprotein affinity. However, acidic residues at both termini still showed relatively large peak perturbation. These results at the residue level suggested that intermolecular interactions between Fd and SiR are electrostatic in nature and the electrostatic interaction is a dominant contributor to form the Fd:SiR complex. We suggest that a combination of calorimetry and NMR is a powerful approach to investigating protein-protein interactions.

  • a new structural insight into differential interaction of cyanobacterial and plant Ferredoxins with nitrite reductase as revealed by nmr and x ray crystallographic studies
    Journal of Biochemistry, 2012
    Co-Authors: Yukiko Sakakibara, Genji Kurisu, Takahisa Ikegami, Hitoshi Kimura, Akira Iwamura, Takashi Saitoh, Toshiharu Hase
    Abstract:

    Ferredoxin (Fd), which plays a pivotal role in photosynthesis as an electron carrier, forms a transient complex with various Fd-dependent enzymes, such as nitrite reductase (NiR), to achieve efficient intermolecular electron transfer. We studied the protein-protein interaction of Fd and NiR by NMR spectroscopy and determined three acidic regions of Fd to be major sites for the interaction with NiR, indicating that the complex is stabilized through electrostatic interaction. During this study, we found Fds from higher plant and cyanobacterium, in spite of their high structural similarities including the above acidic regions, differ remarkably in the interaction with cyanobacterial NiR. In activity assay of NiR, K(m) value for maize Fd (74.6 µM) was 9.6 times larger than that for Leptolyngbya boryana Fd (7.8 µM). The two Fds also showed a similar difference in binding assay to NiR-immobilized resin. Comparative site-specific mutagenesis of two Fds revealed that their discriminative ability for the interaction with NiR is attributed mainly to non-charged residues in the peripheral region of [2Fe-2S] cluster. These non-charged residues are conserved separately between Fds of plant and cyanobacterial origins. Our data highlight that intermolecular force(s) other than electrostatic attraction is(are) also crucial for the molecular interaction between Fd and partner enzyme.

  • crystallization and preliminary x ray studies of an electron transfer complex of Ferredoxin and Ferredoxin dependent glutamate synthase from the cyanobacterium leptolyngbya boryana
    Acta Crystallographica Section F-structural Biology and Crystallization Communications, 2012
    Co-Authors: Kanako Shinmura, Toshiharu Hase, Norifumi Muraki, Ayako Yoshida, Genji Kurisu
    Abstract:

    Ferredoxin (Fd) dependent glutamate synthase (Fd-GOGAT) is a key enzyme involved in nitrogen assimilation that catalyzes the two-electron reductive conversion of Gln and 2-oxoglutarate to two molecules of Glu. Fd serves as an electron donor for Fd-GOGAT and the two proteins form a transient electron-transfer complex. In this study, these two proteins were cocrystallized using the hanging-drop vapour-diffusion method. Diffraction data were collected and processed at 2.65 A resolution. The crystals belonged to space group P43, with unit-cell parameters a = b = 84.95, c = 476.31 A.

Jonathan J Silberg - One of the best experts on this subject based on the ideXlab platform.

  • recombination of 2fe 2s Ferredoxins reveals differences in the inheritance of thermostability and midpoint potential
    ACS Synthetic Biology, 2020
    Co-Authors: Ian J Campbell, Joshua T Atkinson, George N Bennett, Dimithree Kahanda, Othneil N Sparks, Jinyoung Kim, Chiaping Tseng, Rafael Verduzco, Jonathan J Silberg
    Abstract:

    Recombination can be used in the laboratory to overcome component limitations in synthetic biology by creating enzymes that exhibit distinct activities and stabilities from native proteins. To investigate how recombination affects the properties of an oxidoreductase that transfers electrons in cells, we created Ferredoxin (Fd) chimeras by recombining distantly related cyanobacterial and cyanomyophage Fds (53% identity) that present similar midpoint potentials but distinct thermostabilities. Fd chimeras having a wide range of amino acid substitutions retained the ability to coordinate an iron-sulfur cluster, although their thermostabilities varied with the fraction of residues inherited from each parent. The midpoint potentials of chimeric Fds also varied. However, all of the synthetic Fds exhibited midpoint potentials outside of the parental protein range. Each of the chimeric Fds could also support electron transfer between Fd-NADP reductase and sulfite reductase in Escherichia coli, although the chimeric Fds varied in the expression required for similar levels of cellular electron transfer. These results show how Fds can be diversified through recombination and reveal differences in the inheritance of thermostability and electrochemical properties. Furthermore, they illustrate how electron transfer efficiencies of chimeric Fds can be rapidly evaluated using a synthetic metabolic pathway.

  • recombination of 2fe 2s Ferredoxins reveals differences in the inheritance of thermostability and midpoint potential
    bioRxiv, 2020
    Co-Authors: Ian J Campbell, Joshua T Atkinson, George N Bennett, Dimithree Kahanda, Othneil N Sparks, Jinyoung Kim, Chiaping Tseng, Rafael Verduzco, Jonathan J Silberg
    Abstract:

    Homologous recombination can be used to create enzymes that exhibit distinct activities and stabilities from proteins in nature, allowing researchers to overcome component limitations in synthetic biology. To investigate how recombination affects the physical properties of an oxidoreductase that transfers electrons, we created Ferredoxin (Fd) chimeras by recombining distantly-related cyanobacterial and cyanomyophage Fds that present similar midpoint potentials but distinct thermostabilities. Fd chimeras having a wide range of amino acid substitutions retained the ability to coordinate an iron-sulfur cluster, although their thermostabilities varied with the fraction of residues inherited from each parent. The midpoint potentials of chimeric Fds also varied. However, all of the synthetic Fds exhibited midpoint potentials outside of the parental protein range. Each of the chimeric Fds could also be used to build synthetic pathways that support electron transfer between Fd-NADP reductase and sulfite reductase in Escherichia coli, although the chimeric Fds varied in the expression required to support similar levels of cellular electron transfer. These results show how recombination can be used to rapidly diversify the physical properties of protein electron carriers and reveal differences in the inheritance of thermostability and electrochemical properties. Furthermore, they illustrate how electron transfer efficiencies of chimeric Fds can be rapidly evaluated using a synthetic electron transfer pathway.

  • prochlorococcus phage Ferredoxin structural characterization and electron transfer to cyanobacterial sulfite reductases
    Journal of Biological Chemistry, 2020
    Co-Authors: Ian J Campbell, Joshua T Atkinson, George N Bennett, Dimithree Kahanda, Jose L Olmos, Weijun Xu, Othneil N Sparks, Mitchell D Miller, George N Phillips, Jonathan J Silberg
    Abstract:

    Marine cyanobacteria are infected by phages whose genomes encode Ferredoxin (Fd) electron carriers. These Fds are thought to redirect the energy harvested from light to phage-encoded oxidoreductases that enhance viral fitness, but it is unclear how the biophysical properties and partner specificities of phage Fds relate to those of photosynthetic organisms. Here, results of a bioinformatics analysis using a sequence similarity network revealed that phage Fds are most closely related to cyanobacterial Fds that transfer electrons from photosystems to oxidoreductases involved in nutrient assimilation. Structural analysis of myovirus P-SSM2 Fd (pssm2-Fd), which infects the cyanobacterium Prochlorococcus marinus, revealed high levels of similarity to cyanobacterial Fds (root mean square deviations of ≤0.5 A). Additionally, pssm2-Fd exhibited a low midpoint reduction potential (-336 mV versus a standard hydrogen electrode), similar to other photosynthetic Fds, although it had lower thermostability (Tm = 28 °C) than did many other Fds. When expressed in an Escherichia coli strain deficient in sulfite assimilation, pssm2-Fd complemented bacterial growth when coexpressed with a P. marinus sulfite reductase, revealing that pssm2-Fd can transfer electrons to a host protein involved in nutrient assimilation. The high levels of structural similarity with cyanobacterial Fds and reactivity with a host sulfite reductase suggest that phage Fds evolved to transfer electrons to cyanobacterially encoded oxidoreductases.

  • prochlorococcus phage Ferredoxin structural characterization and electron transfer to cyanobacterial sulfite reductases
    bioRxiv, 2020
    Co-Authors: Ian J Campbell, Joshua T Atkinson, George N Bennett, Dimithree Kahanda, Jose L Olmos, Weijun Xu, Othneil N Sparks, Mitchell D Miller, George N Phillips, Jonathan J Silberg
    Abstract:

    Marine cyanobacteria are infected by phage whose genomes encode Ferredoxin (Fd) electron carriers. While these Fds are thought to redirect the energy harvested from light to phage-encoded oxidoreductases that enhance viral fitness, it is not clear how the biophysical properties and partner specificities of phage Fds relate to those in photosynthetic organisms. Bioinformatic analysis using a sequence similarity network revealed that phage Fds are most closely related to cyanobacterial Fds that transfer electrons from photosystems to oxidoreductases involved in nutrient assimilation. Structural analysis of myovirus P-SSM2 Fd (pssm2-Fd), which infects Prochlorococcus marinus, revealed high similarity to cyanobacterial Fds (≤0.5 A RMSD). Additionally, pssm2-Fd exhibits a low midpoint reduction potential (-336 mV vs. SHE) similar to other photosynthetic Fds, albeit lower thermostability (Tm = 28°C) than many Fds. When expressed in an Escherichia coli strain with a sulfite assimilation defect, pssm2-Fd complemented growth when coexpressed with a Prochlorococcus marinus sulfite reductase, revealing that pssm2-Fd can transfer electrons to a host protein involved in nutrient assimilation. The high structural similarity with cyanobacterial Fds and reactivity with a host sulfite reductase suggest that phage Fds evolved to transfer electrons to cyanobacterial-encoded oxidoreductases.

  • evolutionary relationships between low potential Ferredoxin and flavodoxin electron carriers
    Frontiers in Energy Research, 2019
    Co-Authors: Ian J Campbell, George N Bennett, Jonathan J Silberg
    Abstract:

    Proteins from the Ferredoxin (Fd) and flavodoxin (Fld) families function as low potential electrical transfer hubs in cells, at times mediating electron transfer between overlapping sets of oxidoreductases. To better understand protein electron carrier (PEC) use across the domains of life, we evaluated the distribution of genes encoding [4Fe-4S] Fd, [2Fe-2S] Fd, and Fld electron carriers in over seven thousand organisms. Our analysis targeted genes encoding small PEC genes encoding proteins having ≤200 residues. We find that the average number of small PEC genes per Archaea (~13), Bacteria (~8), and Eukarya (~3) genome varies, with some organisms containing as many as 54 total PEC genes. Organisms fall into three groups, including those lacking genes encoding low potential PECs (3%), specialists with a single PEC gene type (20%), and generalists that utilize multiple PEC types (77%). Mapping PEC gene usage onto an evolutionary tree highlights the prevalence of [4Fe-4S] Fds in ancient organisms that are deeply rooted, the expansion of [2Fe-2S] Fds with the advent of photosynthesis and a concomitant decrease in [4Fe-4S] Fds, and the expansion of Flds in organisms that inhabit low-iron host environments. Surprisingly, [4Fe-4S] Fds present a similar abundance in aerobes as [2Fe-2S] Fds. This bioinformatic study highlights understudied PECs whose structure, stability, and partner specificity should be further characterized.

Nestor Carrillo - One of the best experts on this subject based on the ideXlab platform.

  • enhanced plant tolerance to iron starvation by functional substitution of chloroplast Ferredoxin with a bacterial flavodoxin
    Proceedings of the National Academy of Sciences of the United States of America, 2007
    Co-Authors: Vanesa B Tognetti, María F. Fillat, Mohammadreza Hajirezaei, Estela M Valle, Matias D Zurbriggen, Eligio N Morandi, Nestor Carrillo
    Abstract:

    Iron limitation affects one-third of the cultivable land on Earth and represents a major concern for agriculture. It causes decline of many photosynthetic components, including the Fe-S protein Ferredoxin (Fd), involved in essential oxidoreductive pathways of chloroplasts. In cyanobacteria and some algae, Fd down-regulation under Fe deficit is compensated by induction of an isofunctional electron carrier, flavodoxin (Fld), a flavin mononucleotide-containing protein not found in plants. Transgenic tobacco lines expressing a cyanobacterial Fld in chloroplasts were able to grow in Fe-deficient media that severely compromised survival of WT plants. Fld expression did not improve Fe uptake or mobilization, and stressed transformants elicited a normal deficit response, including induction of ferric-chelate reductase and metal transporters. However, the presence of Fld did prevent decrease of several photosynthetic proteins (but not Fd) and partially protected photosynthesis from inactivation. It also preserved the activation state of enzymes depending on the Fd-thioredoxin pathway, which correlated with higher levels of intermediates of carbohydrate metabolism and the Calvin cycle, as well as increased contents of sucrose, glutamate, and other amino acids. These metabolic routes depend, directly or indirectly, on the provision of reduced Fd. The results indicate that Fld could compensate Fd decline during episodes of Fe deficiency by productively interacting with Fd-dependent pathways of the host, providing fresh genetic resources for the design of plants able to survive in Fe-poor lands.

  • stress inducible flavodoxin from photosynthetic microorganisms the mystery of flavodoxin loss from the plant genome
    Iubmb Life, 2007
    Co-Authors: Matias D Zurbriggen, Vanesa B Tognetti, Nestor Carrillo
    Abstract:

    Flavodoxins (Flds) are mobile electron carriers containing flavin mononucleotide as the prosthetic group. They are isofunctional with the ubiquitous electron shuttle Ferredoxin (Fd), mediating essentially the same redox processes among a promiscuous lot of donors and acceptors. While Fds are distributed throughout all kingdoms from prokaryotes to animals, Flds are only found in some bacteria and oceanic algae, in which they are induced to replace Fd functions under conditions of iron starvation and environmental stress that cause Fd decline. They thus play a key adaptive role in photosynthetic microorganisms, allowing survival and reproduction under adverse situations. The Fld gene disappeared from the plant genome somewhere between the green algal ancestor and the first terrestrial plants, and the advantages of this adaptive resource were irreversibly lost. However, reintroduction of a cyanobacterial Fld gene in the chloroplasts of transgenic tobacco resulted in remarkably enhanced tolerance to iron starvation and abiotic stress, indicating that the compensatory functions of Fld were still valuable in higher plants. A hypothesis is formulated to explain why Fld, in spite of its proven advantage, was lost from the plant genetic pool. The contention is based on two tenets: (i) iron availability was the major imperative for Fld conservation and adaptive value, and (ii) photosynthetic eukaryotes followed a succession of ecological adaptations, from the open oceans to coastal regions, and from there to the firm land, facing very different scenarios with respect to iron abundance and accessibility. IUBMB Life, 59: 355-360, 2007

  • functional replacement of Ferredoxin by a cyanobacterial flavodoxin in tobacco confers broad range stress tolerance
    The Plant Cell, 2006
    Co-Authors: Vanesa B Tognetti, María F. Fillat, Javier F Palatnik, Michael Melzer, Mohammadreza Hajirezaei, Estela M Valle, Nestor Carrillo
    Abstract:

    Chloroplast Ferredoxin (Fd) plays a pivotal role in plant cell metabolism by delivering reducing equivalents to various essential oxidoreductive pathways. Fd levels decrease under adverse environmental conditions in many microorganisms, including cyanobacteria, which share a common ancestor with chloroplasts. Conversely, stress situations induce the synthesis of flavodoxin (Fld), an electron carrier flavoprotein not found in plants, which can efficiently replace Fd in most electron transfer processes. We report here that chloroplast Fd also declined in plants exposed to oxidants or stress conditions. A purified cyanobacterial Fld was able to mediate plant Fd-dependent reactions in vitro, including NADP+ and thioredoxin reduction. Tobacco (Nicotiana tabacum) plants expressing Fld in chloroplasts displayed increased tolerance to multiple sources of stress, including redox-cycling herbicides, extreme temperatures, high irradiation, water deficit, and UV radiation. Oxidant buildup and oxidative inactivation of thioredoxin-dependent plastidic enzymes were decreased in stressed plants expressing plastid-targeted Fld, suggesting that development of the tolerant phenotype relied on productive interaction of this flavoprotein with Fd-dependent oxidoreductive pathways of the host, most remarkably, thioredoxin reduction. The use of Fld provides new tools to investigate the requirements of photosynthesis in planta and to increase plant stress tolerance based on the introduction of a cyanobacterial product that is free from endogenous regulation in higher plants.

Vanesa B Tognetti - One of the best experts on this subject based on the ideXlab platform.

  • Functional Replacement of Ferredoxin by a Cyanobacterial Flavodoxin in Tobacco Confers Broad-Range Stress Tolerance W
    2013
    Co-Authors: Vanesa B Tognetti, Javier F Palatnik, Mohammadreza Hajirezaei, Estela M Valle, Maríaf. A Fillat, Michael B Melzer, Néstor Carrilloa, Slrk Rosario
    Abstract:

    Chloroplast Ferredoxin (Fd) plays a pivotal role in plant cell metabolism by delivering reducing equivalents to various essential oxidoreductive pathways. Fd levels decrease under adverse environmental conditions in many microorganisms, including cyanobacteria, which share a common ancestor with chloroplasts. Conversely, stress situations induce the synthesis of flavodoxin (Fld), an electron carrier flavoprotein not found in plants, which can efficiently replace Fd in most electron transfer processes. We report here that chloroplast Fd also declined in plants exposed to oxidants or stress conditions. A purified cyanobacterial Fld was able to mediate plant Fd-dependent reactions in vitro, including NADP 1 and thioredoxin reduction. Tobacco (Nicotiana tabacum) plants expressing Fld in chloroplasts displayed increased tolerance to multiple sources of stress, including redox-cycling herbicides, extreme temperatures, high irradiation, water deficit, and UV radiation. Oxidant buildup and oxidative inactivation of thioredoxin-dependent plastidic enzymes were decreased in stressed plants expressing plastid-targeted Fld, suggesting that development of the tolerant phenotype relied on productive interaction of this flavoprotein with Fd-dependent oxidoreductive pathways of the host, most remarkably, thioredoxin reduction. The use of Fld provides new tools to investigate the requirements of photosynthesis in planta and to increase plant stress tolerance based on the introduction of a cyanobacterial product that is free from endogenous regulation i

  • enhanced plant tolerance to iron starvation by functional substitution of chloroplast Ferredoxin with a bacterial flavodoxin
    Proceedings of the National Academy of Sciences of the United States of America, 2007
    Co-Authors: Vanesa B Tognetti, María F. Fillat, Mohammadreza Hajirezaei, Estela M Valle, Matias D Zurbriggen, Eligio N Morandi, Nestor Carrillo
    Abstract:

    Iron limitation affects one-third of the cultivable land on Earth and represents a major concern for agriculture. It causes decline of many photosynthetic components, including the Fe-S protein Ferredoxin (Fd), involved in essential oxidoreductive pathways of chloroplasts. In cyanobacteria and some algae, Fd down-regulation under Fe deficit is compensated by induction of an isofunctional electron carrier, flavodoxin (Fld), a flavin mononucleotide-containing protein not found in plants. Transgenic tobacco lines expressing a cyanobacterial Fld in chloroplasts were able to grow in Fe-deficient media that severely compromised survival of WT plants. Fld expression did not improve Fe uptake or mobilization, and stressed transformants elicited a normal deficit response, including induction of ferric-chelate reductase and metal transporters. However, the presence of Fld did prevent decrease of several photosynthetic proteins (but not Fd) and partially protected photosynthesis from inactivation. It also preserved the activation state of enzymes depending on the Fd-thioredoxin pathway, which correlated with higher levels of intermediates of carbohydrate metabolism and the Calvin cycle, as well as increased contents of sucrose, glutamate, and other amino acids. These metabolic routes depend, directly or indirectly, on the provision of reduced Fd. The results indicate that Fld could compensate Fd decline during episodes of Fe deficiency by productively interacting with Fd-dependent pathways of the host, providing fresh genetic resources for the design of plants able to survive in Fe-poor lands.

  • stress inducible flavodoxin from photosynthetic microorganisms the mystery of flavodoxin loss from the plant genome
    Iubmb Life, 2007
    Co-Authors: Matias D Zurbriggen, Vanesa B Tognetti, Nestor Carrillo
    Abstract:

    Flavodoxins (Flds) are mobile electron carriers containing flavin mononucleotide as the prosthetic group. They are isofunctional with the ubiquitous electron shuttle Ferredoxin (Fd), mediating essentially the same redox processes among a promiscuous lot of donors and acceptors. While Fds are distributed throughout all kingdoms from prokaryotes to animals, Flds are only found in some bacteria and oceanic algae, in which they are induced to replace Fd functions under conditions of iron starvation and environmental stress that cause Fd decline. They thus play a key adaptive role in photosynthetic microorganisms, allowing survival and reproduction under adverse situations. The Fld gene disappeared from the plant genome somewhere between the green algal ancestor and the first terrestrial plants, and the advantages of this adaptive resource were irreversibly lost. However, reintroduction of a cyanobacterial Fld gene in the chloroplasts of transgenic tobacco resulted in remarkably enhanced tolerance to iron starvation and abiotic stress, indicating that the compensatory functions of Fld were still valuable in higher plants. A hypothesis is formulated to explain why Fld, in spite of its proven advantage, was lost from the plant genetic pool. The contention is based on two tenets: (i) iron availability was the major imperative for Fld conservation and adaptive value, and (ii) photosynthetic eukaryotes followed a succession of ecological adaptations, from the open oceans to coastal regions, and from there to the firm land, facing very different scenarios with respect to iron abundance and accessibility. IUBMB Life, 59: 355-360, 2007

  • functional replacement of Ferredoxin by a cyanobacterial flavodoxin in tobacco confers broad range stress tolerance
    The Plant Cell, 2006
    Co-Authors: Vanesa B Tognetti, María F. Fillat, Javier F Palatnik, Michael Melzer, Mohammadreza Hajirezaei, Estela M Valle, Nestor Carrillo
    Abstract:

    Chloroplast Ferredoxin (Fd) plays a pivotal role in plant cell metabolism by delivering reducing equivalents to various essential oxidoreductive pathways. Fd levels decrease under adverse environmental conditions in many microorganisms, including cyanobacteria, which share a common ancestor with chloroplasts. Conversely, stress situations induce the synthesis of flavodoxin (Fld), an electron carrier flavoprotein not found in plants, which can efficiently replace Fd in most electron transfer processes. We report here that chloroplast Fd also declined in plants exposed to oxidants or stress conditions. A purified cyanobacterial Fld was able to mediate plant Fd-dependent reactions in vitro, including NADP+ and thioredoxin reduction. Tobacco (Nicotiana tabacum) plants expressing Fld in chloroplasts displayed increased tolerance to multiple sources of stress, including redox-cycling herbicides, extreme temperatures, high irradiation, water deficit, and UV radiation. Oxidant buildup and oxidative inactivation of thioredoxin-dependent plastidic enzymes were decreased in stressed plants expressing plastid-targeted Fld, suggesting that development of the tolerant phenotype relied on productive interaction of this flavoprotein with Fd-dependent oxidoreductive pathways of the host, most remarkably, thioredoxin reduction. The use of Fld provides new tools to investigate the requirements of photosynthesis in planta and to increase plant stress tolerance based on the introduction of a cyanobacterial product that is free from endogenous regulation in higher plants.

Ian J Campbell - One of the best experts on this subject based on the ideXlab platform.

  • recombination of 2fe 2s Ferredoxins reveals differences in the inheritance of thermostability and midpoint potential
    ACS Synthetic Biology, 2020
    Co-Authors: Ian J Campbell, Joshua T Atkinson, George N Bennett, Dimithree Kahanda, Othneil N Sparks, Jinyoung Kim, Chiaping Tseng, Rafael Verduzco, Jonathan J Silberg
    Abstract:

    Recombination can be used in the laboratory to overcome component limitations in synthetic biology by creating enzymes that exhibit distinct activities and stabilities from native proteins. To investigate how recombination affects the properties of an oxidoreductase that transfers electrons in cells, we created Ferredoxin (Fd) chimeras by recombining distantly related cyanobacterial and cyanomyophage Fds (53% identity) that present similar midpoint potentials but distinct thermostabilities. Fd chimeras having a wide range of amino acid substitutions retained the ability to coordinate an iron-sulfur cluster, although their thermostabilities varied with the fraction of residues inherited from each parent. The midpoint potentials of chimeric Fds also varied. However, all of the synthetic Fds exhibited midpoint potentials outside of the parental protein range. Each of the chimeric Fds could also support electron transfer between Fd-NADP reductase and sulfite reductase in Escherichia coli, although the chimeric Fds varied in the expression required for similar levels of cellular electron transfer. These results show how Fds can be diversified through recombination and reveal differences in the inheritance of thermostability and electrochemical properties. Furthermore, they illustrate how electron transfer efficiencies of chimeric Fds can be rapidly evaluated using a synthetic metabolic pathway.

  • recombination of 2fe 2s Ferredoxins reveals differences in the inheritance of thermostability and midpoint potential
    bioRxiv, 2020
    Co-Authors: Ian J Campbell, Joshua T Atkinson, George N Bennett, Dimithree Kahanda, Othneil N Sparks, Jinyoung Kim, Chiaping Tseng, Rafael Verduzco, Jonathan J Silberg
    Abstract:

    Homologous recombination can be used to create enzymes that exhibit distinct activities and stabilities from proteins in nature, allowing researchers to overcome component limitations in synthetic biology. To investigate how recombination affects the physical properties of an oxidoreductase that transfers electrons, we created Ferredoxin (Fd) chimeras by recombining distantly-related cyanobacterial and cyanomyophage Fds that present similar midpoint potentials but distinct thermostabilities. Fd chimeras having a wide range of amino acid substitutions retained the ability to coordinate an iron-sulfur cluster, although their thermostabilities varied with the fraction of residues inherited from each parent. The midpoint potentials of chimeric Fds also varied. However, all of the synthetic Fds exhibited midpoint potentials outside of the parental protein range. Each of the chimeric Fds could also be used to build synthetic pathways that support electron transfer between Fd-NADP reductase and sulfite reductase in Escherichia coli, although the chimeric Fds varied in the expression required to support similar levels of cellular electron transfer. These results show how recombination can be used to rapidly diversify the physical properties of protein electron carriers and reveal differences in the inheritance of thermostability and electrochemical properties. Furthermore, they illustrate how electron transfer efficiencies of chimeric Fds can be rapidly evaluated using a synthetic electron transfer pathway.

  • prochlorococcus phage Ferredoxin structural characterization and electron transfer to cyanobacterial sulfite reductases
    Journal of Biological Chemistry, 2020
    Co-Authors: Ian J Campbell, Joshua T Atkinson, George N Bennett, Dimithree Kahanda, Jose L Olmos, Weijun Xu, Othneil N Sparks, Mitchell D Miller, George N Phillips, Jonathan J Silberg
    Abstract:

    Marine cyanobacteria are infected by phages whose genomes encode Ferredoxin (Fd) electron carriers. These Fds are thought to redirect the energy harvested from light to phage-encoded oxidoreductases that enhance viral fitness, but it is unclear how the biophysical properties and partner specificities of phage Fds relate to those of photosynthetic organisms. Here, results of a bioinformatics analysis using a sequence similarity network revealed that phage Fds are most closely related to cyanobacterial Fds that transfer electrons from photosystems to oxidoreductases involved in nutrient assimilation. Structural analysis of myovirus P-SSM2 Fd (pssm2-Fd), which infects the cyanobacterium Prochlorococcus marinus, revealed high levels of similarity to cyanobacterial Fds (root mean square deviations of ≤0.5 A). Additionally, pssm2-Fd exhibited a low midpoint reduction potential (-336 mV versus a standard hydrogen electrode), similar to other photosynthetic Fds, although it had lower thermostability (Tm = 28 °C) than did many other Fds. When expressed in an Escherichia coli strain deficient in sulfite assimilation, pssm2-Fd complemented bacterial growth when coexpressed with a P. marinus sulfite reductase, revealing that pssm2-Fd can transfer electrons to a host protein involved in nutrient assimilation. The high levels of structural similarity with cyanobacterial Fds and reactivity with a host sulfite reductase suggest that phage Fds evolved to transfer electrons to cyanobacterially encoded oxidoreductases.

  • prochlorococcus phage Ferredoxin structural characterization and electron transfer to cyanobacterial sulfite reductases
    bioRxiv, 2020
    Co-Authors: Ian J Campbell, Joshua T Atkinson, George N Bennett, Dimithree Kahanda, Jose L Olmos, Weijun Xu, Othneil N Sparks, Mitchell D Miller, George N Phillips, Jonathan J Silberg
    Abstract:

    Marine cyanobacteria are infected by phage whose genomes encode Ferredoxin (Fd) electron carriers. While these Fds are thought to redirect the energy harvested from light to phage-encoded oxidoreductases that enhance viral fitness, it is not clear how the biophysical properties and partner specificities of phage Fds relate to those in photosynthetic organisms. Bioinformatic analysis using a sequence similarity network revealed that phage Fds are most closely related to cyanobacterial Fds that transfer electrons from photosystems to oxidoreductases involved in nutrient assimilation. Structural analysis of myovirus P-SSM2 Fd (pssm2-Fd), which infects Prochlorococcus marinus, revealed high similarity to cyanobacterial Fds (≤0.5 A RMSD). Additionally, pssm2-Fd exhibits a low midpoint reduction potential (-336 mV vs. SHE) similar to other photosynthetic Fds, albeit lower thermostability (Tm = 28°C) than many Fds. When expressed in an Escherichia coli strain with a sulfite assimilation defect, pssm2-Fd complemented growth when coexpressed with a Prochlorococcus marinus sulfite reductase, revealing that pssm2-Fd can transfer electrons to a host protein involved in nutrient assimilation. The high structural similarity with cyanobacterial Fds and reactivity with a host sulfite reductase suggest that phage Fds evolved to transfer electrons to cyanobacterial-encoded oxidoreductases.

  • evolutionary relationships between low potential Ferredoxin and flavodoxin electron carriers
    Frontiers in Energy Research, 2019
    Co-Authors: Ian J Campbell, George N Bennett, Jonathan J Silberg
    Abstract:

    Proteins from the Ferredoxin (Fd) and flavodoxin (Fld) families function as low potential electrical transfer hubs in cells, at times mediating electron transfer between overlapping sets of oxidoreductases. To better understand protein electron carrier (PEC) use across the domains of life, we evaluated the distribution of genes encoding [4Fe-4S] Fd, [2Fe-2S] Fd, and Fld electron carriers in over seven thousand organisms. Our analysis targeted genes encoding small PEC genes encoding proteins having ≤200 residues. We find that the average number of small PEC genes per Archaea (~13), Bacteria (~8), and Eukarya (~3) genome varies, with some organisms containing as many as 54 total PEC genes. Organisms fall into three groups, including those lacking genes encoding low potential PECs (3%), specialists with a single PEC gene type (20%), and generalists that utilize multiple PEC types (77%). Mapping PEC gene usage onto an evolutionary tree highlights the prevalence of [4Fe-4S] Fds in ancient organisms that are deeply rooted, the expansion of [2Fe-2S] Fds with the advent of photosynthesis and a concomitant decrease in [4Fe-4S] Fds, and the expansion of Flds in organisms that inhabit low-iron host environments. Surprisingly, [4Fe-4S] Fds present a similar abundance in aerobes as [2Fe-2S] Fds. This bioinformatic study highlights understudied PECs whose structure, stability, and partner specificity should be further characterized.