The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Marianne Guiral - One of the best experts on this subject based on the ideXlab platform.
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Microbe Profile: Aquifex aeolicus: an extreme heat-loving bacterium that feeds on gases and inorganic chemicals.
Microbiology (Reading England), 2021Co-Authors: Marianne Guiral, Marie Thérèse Giudici-orticoniAbstract:The bacterium 'Aquifex aeolicus' is the model organism for the deeply rooted phylum Aquificae. This 'water-maker' is an H2-oxidizing microaerophile that flourishes in extremely hot marine habitats, and it also thrives on the sulphur compounds commonly found in volcanic environments. 'A. aeolicus' has hyper-stable proteins and a fully sequenced genome, with some of its essential metabolic pathways deciphered (including energy conservation). Many of its proteins have also been characterized (especially structurally), including many of the enzymes involved in replication, transcription, RNA processing and cell envelope biosynthesis. Enzymes that are of promise for biotechnological applications have been widely investigated in this species. 'A. aeolicus' has also added to our understanding of the origins of life and evolution.
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Sulfite oxidation by the quinone-reducing molybdenum sulfite dehydrogenase SoeABC from the bacterium Aquifex aeolicus.
Biochimica et biophysica acta. Bioenergetics, 2020Co-Authors: Souhela Boughanemi, Marie Thérèse Giudici-orticoni, Pascale Infossi, Barbara Schoepp-cothenet, Marianne GuiralAbstract:Abstract The microaerophilic bacterium Aquifex aeolicus is a chemolitoautotroph that uses sulfur compounds as electron sources. The model of oxidation of the energetic sulfur compounds in this bacterium predicts that sulfite would probably be a metabolic intermediate released in the cytoplasm. In this work, we purified and characterized a membrane-bound sulfite dehydrogenase, identified as an SoeABC enzyme, that was previously described as a sulfur reductase. It is a member of the DMSO-reductase family of molybdenum enzymes. This type of enzyme was identified a few years ago but never purified, and biochemical data and kinetic properties were completely lacking. An enzyme catalyzing sulfite oxidation using Nitro-blue tetrazolium as artificial electron acceptor was extracted from the membrane fraction of Aquifex aeolicus. The purified enzyme is a dimer of trimer (αβγ)2 of about 390 kDa. The KM for sulfite and kcat values were 34 μM and 567 s−1 respectively, at pH 8.3 and 55 °C. We furthermore showed that SoeABC reduces a UQ10 analogue, the decyl-ubiquinone, as well, with a KM of 2.6 μM and a kcat of 52.9 s−1. It seems to specifically oxidize sulfite but can work in the reverse direction, reduction of sulfur or tetrathionate, using reduced methyl viologen as electron donor. The close phylogenetic relationship of Soe with sulfur and tetrathionate reductases that we established, perfectly explains this enzymatic ability, although its bidirectionality in vivo still needs to be clarified. Oxygen-consumption measurements confirmed that electrons generated by sulfite oxidation in the cytoplasm enter the respiratory chain at the level of quinones.
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Microbial oxidative sulfur metabolism: biochemical evidence of the membrane-bound heterodisulfide reductase-like complex of the bacterium Aquifex aeolicus
FEMS Microbiology Letters, 2016Co-Authors: Souhela Boughanemi, Marie Thérèse Giudici-orticoni, Pascale Infossi, Sabrina Lignon, Jordan Lyonnet, Marielle Bauzan, Artémis Kosta, Marianne GuiralAbstract:The Hdr (heterodisulfide reductase)-like enzyme is predicted, from gene transcript profiling experiments previously published, to be essential in oxidative sulfur metabolism in a number of bacteria and archaea. Nevertheless, no biochemical and physicochemical data are available so far about this enzyme. Genes coding for it were identified in Aquifex aeolicus, a Gram-negative, hyperthermophilic, chemolithoautotrophic and microaerophilic bacterium that uses inorganic sulfur compounds as electron donor to grow. We provide biochemical evidence that this Hdr-like enzyme is present in this sulfur-oxidizing prokaryote (cultivated with thiosulfate or elemental sulfur). We demonstrate, by immunolocalization and cell fractionation, that Hdr-like enzyme is associated, presumably monotopically, with the membrane fraction. We show by co-immunoprecipitation assay or partial purification, that the Hdr proteins form a stable complex composed of at least five subunits, HdrA, HdrB1, HdrB2, HdrC1 and HdrC2, present in two forms of high molecular mass on native gel (∼240 and 450 kDa). These studies allow us to propose a revised model for dissimilatory sulfur oxidation pathways in A. aeolicus, with Hdr predicted to generate sulfite.
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Insertion and self-diffusion of a monotopic protein, the Aquifex aeolicus sulfide quinone reductase, in supported lipid bilayers
European Physical Journal E: Soft matter and biological physics, 2015Co-Authors: Frédéric Harb, Marie Thérèse Giudici-orticoni, Marianne Guiral, Laurence Prunetti, Bernard TinlandAbstract:Monotopic proteins constitute a class of membrane proteins that bind tightly to cell membranes, but do not span them. We present a FRAPP (Fluorescence Recovery After Patterned Photobleaching) study of the dynamics of a bacterial monotopic protein, SQR (sulfide quinone oxidoreductase) from the thermophilic bacteria Aquifex aeolicus, inserted into two different types of lipid bilayers (EggPC: L-α-phosphatidylcholine (Egg, Chicken) and DMPC: 1,2-dimyristoyl-sn-glycero-3-phosphocholine) supported on two different types of support (mica or glass). It sheds light on the behavior of a monotopic protein inside the bilayer. The insertion of SQR is more efficient when the bilayer is in the fluid phase than in the gel phase. We observed diffusion of the protein, with no immobile fraction, and deduced from the diffusion coefficient measurements that the resulting inserted object is the same whatever the incubation conditions, i.e. homogeneous in terms of oligomerization state. As expected, the diffusion coefficient of the SQR is smaller in the gel phase than in the fluid phase. In the supported lipid bilayer, the diffusion coefficient of the SQR is smaller than the diffusion coefficient of phospholipids in both gel and fluid phase. SQR shows a diffusion behavior different from the transmembrane protein α-hemolysin, and consistent with its monotopic character. Preliminary experiments in the presence of the substrate of SQR, DecylUbiquinone, an analogue of quinone, component of transmembrane electrons transport systems of eukaryotic and prokaryotic organisms, have been carried out. Finally, we studied the behavior of SQR, in terms of insertion and diffusion, in bilayers formed with lipids from Aquifex aeolicus. All the conclusions that we have found in the biomimetic systems applied to the biological system
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the hyperthermophilic bacterium Aquifex aeolicus from respiratory pathways to extremely resistant enzymes and biotechnological applications
Advances in Microbial Physiology, 2012Co-Authors: Marianne Guiral, Laurence Prunetti, Pascale Infossi, Alexandre Ciaccafava, Elisabeth Lojou, Clement Aussignargues, Marianne Ilbert, Marietherese GiudiciorticoniAbstract:Abstract Aquifex aeolicus isolated from a shallow submarine hydrothermal system belongs to the order Aquificales which constitute an important component of the microbial communities at elevated temperatures. This hyperthermophilic chemolithoautotrophic bacterium, which utilizes molecular hydrogen, molecular oxygen, and inorganic sulfur compounds to flourish, uses the reductive TCA cycle for CO2 fixation. In this review, the intricate energy metabolism of A. aeolicus is described. As the chemistry of sulfur is complex and multiple sulfur species can be generated, A. aeolicus possesses a multitude of different enzymes related to the energy sulfur metabolism. It contains also membrane-embedded [NiFe] hydrogenases as well as oxidases enzymes involved in hydrogen and oxygen utilization. We have focused on some of these proteins that have been extensively studied and characterized as super-resistant enzymes with outstanding properties. We discuss the potential use of hydrogenases in an attractive H2/O2 biofuel cell in replacement of chemical catalysts. Using complete genomic sequence and biochemical data, we present here a global view of the energy-generating mechanisms of A. aeolicus including sulfur compounds reduction and oxidation pathways as well as hydrogen and oxygen utilization.
Pascale Infossi - One of the best experts on this subject based on the ideXlab platform.
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Sulfite oxidation by the quinone-reducing molybdenum sulfite dehydrogenase SoeABC from the bacterium Aquifex aeolicus.
Biochimica et biophysica acta. Bioenergetics, 2020Co-Authors: Souhela Boughanemi, Marie Thérèse Giudici-orticoni, Pascale Infossi, Barbara Schoepp-cothenet, Marianne GuiralAbstract:Abstract The microaerophilic bacterium Aquifex aeolicus is a chemolitoautotroph that uses sulfur compounds as electron sources. The model of oxidation of the energetic sulfur compounds in this bacterium predicts that sulfite would probably be a metabolic intermediate released in the cytoplasm. In this work, we purified and characterized a membrane-bound sulfite dehydrogenase, identified as an SoeABC enzyme, that was previously described as a sulfur reductase. It is a member of the DMSO-reductase family of molybdenum enzymes. This type of enzyme was identified a few years ago but never purified, and biochemical data and kinetic properties were completely lacking. An enzyme catalyzing sulfite oxidation using Nitro-blue tetrazolium as artificial electron acceptor was extracted from the membrane fraction of Aquifex aeolicus. The purified enzyme is a dimer of trimer (αβγ)2 of about 390 kDa. The KM for sulfite and kcat values were 34 μM and 567 s−1 respectively, at pH 8.3 and 55 °C. We furthermore showed that SoeABC reduces a UQ10 analogue, the decyl-ubiquinone, as well, with a KM of 2.6 μM and a kcat of 52.9 s−1. It seems to specifically oxidize sulfite but can work in the reverse direction, reduction of sulfur or tetrathionate, using reduced methyl viologen as electron donor. The close phylogenetic relationship of Soe with sulfur and tetrathionate reductases that we established, perfectly explains this enzymatic ability, although its bidirectionality in vivo still needs to be clarified. Oxygen-consumption measurements confirmed that electrons generated by sulfite oxidation in the cytoplasm enter the respiratory chain at the level of quinones.
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Microbial oxidative sulfur metabolism: biochemical evidence of the membrane-bound heterodisulfide reductase-like complex of the bacterium Aquifex aeolicus
FEMS Microbiology Letters, 2016Co-Authors: Souhela Boughanemi, Marie Thérèse Giudici-orticoni, Pascale Infossi, Sabrina Lignon, Jordan Lyonnet, Marielle Bauzan, Artémis Kosta, Marianne GuiralAbstract:The Hdr (heterodisulfide reductase)-like enzyme is predicted, from gene transcript profiling experiments previously published, to be essential in oxidative sulfur metabolism in a number of bacteria and archaea. Nevertheless, no biochemical and physicochemical data are available so far about this enzyme. Genes coding for it were identified in Aquifex aeolicus, a Gram-negative, hyperthermophilic, chemolithoautotrophic and microaerophilic bacterium that uses inorganic sulfur compounds as electron donor to grow. We provide biochemical evidence that this Hdr-like enzyme is present in this sulfur-oxidizing prokaryote (cultivated with thiosulfate or elemental sulfur). We demonstrate, by immunolocalization and cell fractionation, that Hdr-like enzyme is associated, presumably monotopically, with the membrane fraction. We show by co-immunoprecipitation assay or partial purification, that the Hdr proteins form a stable complex composed of at least five subunits, HdrA, HdrB1, HdrB2, HdrC1 and HdrC2, present in two forms of high molecular mass on native gel (∼240 and 450 kDa). These studies allow us to propose a revised model for dissimilatory sulfur oxidation pathways in A. aeolicus, with Hdr predicted to generate sulfite.
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Light-induced reactivation of O2-tolerant membrane-bound [Ni-Fe] hydrogenase from the hyperthermophilic bacterium Aquifex aeolicus under turnover conditions.
Physical Chemistry Chemical Physics, 2013Co-Authors: Alexandre Ciaccafava, Marie Thérèse Giudici-orticoni, Pascale Infossi, Cyrille Hamon, Valérie Marchi, Elisabeth LojouAbstract:We report the effect of UV-Vis light on the membrane-bound [Ni-Fe] hydrogenase from Aquifex aeolicus under turnover conditions. Using electrochemistry, we show a potential dependent light sensitivity and propose that a light-induced structural change of the [Ni-Fe] active site is related to an enhanced reactivation of the hydrogenase under illumination at high potentials.
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spectroscopic characterization of the key catalytic intermediate ni c in the o2 tolerant nife hydrogenase i from Aquifex aeolicus evidence of a weakly bound hydride
Chemical Communications, 2012Co-Authors: Mariaeirini Pandelia, Pascale Infossi, Matthias Stein, Marietherese Giudiciorticoni, Wolfgang LubitzAbstract:Ni–C in the O2-tolerant hydrogenase I from Aquifex aeolicus binds a hydride weaker than that in O2-sensitive hydrogenases. This is in line with the enhanced light-sensitivity of Ni–C, greater lability of the hydride complex and increased catalytic redox potentials relevant to bio-H2 oxidation.
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the hyperthermophilic bacterium Aquifex aeolicus from respiratory pathways to extremely resistant enzymes and biotechnological applications
Advances in Microbial Physiology, 2012Co-Authors: Marianne Guiral, Laurence Prunetti, Pascale Infossi, Alexandre Ciaccafava, Elisabeth Lojou, Clement Aussignargues, Marianne Ilbert, Marietherese GiudiciorticoniAbstract:Abstract Aquifex aeolicus isolated from a shallow submarine hydrothermal system belongs to the order Aquificales which constitute an important component of the microbial communities at elevated temperatures. This hyperthermophilic chemolithoautotrophic bacterium, which utilizes molecular hydrogen, molecular oxygen, and inorganic sulfur compounds to flourish, uses the reductive TCA cycle for CO2 fixation. In this review, the intricate energy metabolism of A. aeolicus is described. As the chemistry of sulfur is complex and multiple sulfur species can be generated, A. aeolicus possesses a multitude of different enzymes related to the energy sulfur metabolism. It contains also membrane-embedded [NiFe] hydrogenases as well as oxidases enzymes involved in hydrogen and oxygen utilization. We have focused on some of these proteins that have been extensively studied and characterized as super-resistant enzymes with outstanding properties. We discuss the potential use of hydrogenases in an attractive H2/O2 biofuel cell in replacement of chemical catalysts. Using complete genomic sequence and biochemical data, we present here a global view of the energy-generating mechanisms of A. aeolicus including sulfur compounds reduction and oxidation pathways as well as hydrogen and oxygen utilization.
Marie Thérèse Giudici-orticoni - One of the best experts on this subject based on the ideXlab platform.
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Microbe Profile: Aquifex aeolicus: an extreme heat-loving bacterium that feeds on gases and inorganic chemicals.
Microbiology (Reading England), 2021Co-Authors: Marianne Guiral, Marie Thérèse Giudici-orticoniAbstract:The bacterium 'Aquifex aeolicus' is the model organism for the deeply rooted phylum Aquificae. This 'water-maker' is an H2-oxidizing microaerophile that flourishes in extremely hot marine habitats, and it also thrives on the sulphur compounds commonly found in volcanic environments. 'A. aeolicus' has hyper-stable proteins and a fully sequenced genome, with some of its essential metabolic pathways deciphered (including energy conservation). Many of its proteins have also been characterized (especially structurally), including many of the enzymes involved in replication, transcription, RNA processing and cell envelope biosynthesis. Enzymes that are of promise for biotechnological applications have been widely investigated in this species. 'A. aeolicus' has also added to our understanding of the origins of life and evolution.
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Sulfite oxidation by the quinone-reducing molybdenum sulfite dehydrogenase SoeABC from the bacterium Aquifex aeolicus.
Biochimica et biophysica acta. Bioenergetics, 2020Co-Authors: Souhela Boughanemi, Marie Thérèse Giudici-orticoni, Pascale Infossi, Barbara Schoepp-cothenet, Marianne GuiralAbstract:Abstract The microaerophilic bacterium Aquifex aeolicus is a chemolitoautotroph that uses sulfur compounds as electron sources. The model of oxidation of the energetic sulfur compounds in this bacterium predicts that sulfite would probably be a metabolic intermediate released in the cytoplasm. In this work, we purified and characterized a membrane-bound sulfite dehydrogenase, identified as an SoeABC enzyme, that was previously described as a sulfur reductase. It is a member of the DMSO-reductase family of molybdenum enzymes. This type of enzyme was identified a few years ago but never purified, and biochemical data and kinetic properties were completely lacking. An enzyme catalyzing sulfite oxidation using Nitro-blue tetrazolium as artificial electron acceptor was extracted from the membrane fraction of Aquifex aeolicus. The purified enzyme is a dimer of trimer (αβγ)2 of about 390 kDa. The KM for sulfite and kcat values were 34 μM and 567 s−1 respectively, at pH 8.3 and 55 °C. We furthermore showed that SoeABC reduces a UQ10 analogue, the decyl-ubiquinone, as well, with a KM of 2.6 μM and a kcat of 52.9 s−1. It seems to specifically oxidize sulfite but can work in the reverse direction, reduction of sulfur or tetrathionate, using reduced methyl viologen as electron donor. The close phylogenetic relationship of Soe with sulfur and tetrathionate reductases that we established, perfectly explains this enzymatic ability, although its bidirectionality in vivo still needs to be clarified. Oxygen-consumption measurements confirmed that electrons generated by sulfite oxidation in the cytoplasm enter the respiratory chain at the level of quinones.
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Microbial oxidative sulfur metabolism: biochemical evidence of the membrane-bound heterodisulfide reductase-like complex of the bacterium Aquifex aeolicus
FEMS Microbiology Letters, 2016Co-Authors: Souhela Boughanemi, Marie Thérèse Giudici-orticoni, Pascale Infossi, Sabrina Lignon, Jordan Lyonnet, Marielle Bauzan, Artémis Kosta, Marianne GuiralAbstract:The Hdr (heterodisulfide reductase)-like enzyme is predicted, from gene transcript profiling experiments previously published, to be essential in oxidative sulfur metabolism in a number of bacteria and archaea. Nevertheless, no biochemical and physicochemical data are available so far about this enzyme. Genes coding for it were identified in Aquifex aeolicus, a Gram-negative, hyperthermophilic, chemolithoautotrophic and microaerophilic bacterium that uses inorganic sulfur compounds as electron donor to grow. We provide biochemical evidence that this Hdr-like enzyme is present in this sulfur-oxidizing prokaryote (cultivated with thiosulfate or elemental sulfur). We demonstrate, by immunolocalization and cell fractionation, that Hdr-like enzyme is associated, presumably monotopically, with the membrane fraction. We show by co-immunoprecipitation assay or partial purification, that the Hdr proteins form a stable complex composed of at least five subunits, HdrA, HdrB1, HdrB2, HdrC1 and HdrC2, present in two forms of high molecular mass on native gel (∼240 and 450 kDa). These studies allow us to propose a revised model for dissimilatory sulfur oxidation pathways in A. aeolicus, with Hdr predicted to generate sulfite.
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Insertion and self-diffusion of a monotopic protein, the Aquifex aeolicus sulfide quinone reductase, in supported lipid bilayers
European Physical Journal E: Soft matter and biological physics, 2015Co-Authors: Frédéric Harb, Marie Thérèse Giudici-orticoni, Marianne Guiral, Laurence Prunetti, Bernard TinlandAbstract:Monotopic proteins constitute a class of membrane proteins that bind tightly to cell membranes, but do not span them. We present a FRAPP (Fluorescence Recovery After Patterned Photobleaching) study of the dynamics of a bacterial monotopic protein, SQR (sulfide quinone oxidoreductase) from the thermophilic bacteria Aquifex aeolicus, inserted into two different types of lipid bilayers (EggPC: L-α-phosphatidylcholine (Egg, Chicken) and DMPC: 1,2-dimyristoyl-sn-glycero-3-phosphocholine) supported on two different types of support (mica or glass). It sheds light on the behavior of a monotopic protein inside the bilayer. The insertion of SQR is more efficient when the bilayer is in the fluid phase than in the gel phase. We observed diffusion of the protein, with no immobile fraction, and deduced from the diffusion coefficient measurements that the resulting inserted object is the same whatever the incubation conditions, i.e. homogeneous in terms of oligomerization state. As expected, the diffusion coefficient of the SQR is smaller in the gel phase than in the fluid phase. In the supported lipid bilayer, the diffusion coefficient of the SQR is smaller than the diffusion coefficient of phospholipids in both gel and fluid phase. SQR shows a diffusion behavior different from the transmembrane protein α-hemolysin, and consistent with its monotopic character. Preliminary experiments in the presence of the substrate of SQR, DecylUbiquinone, an analogue of quinone, component of transmembrane electrons transport systems of eukaryotic and prokaryotic organisms, have been carried out. Finally, we studied the behavior of SQR, in terms of insertion and diffusion, in bilayers formed with lipids from Aquifex aeolicus. All the conclusions that we have found in the biomimetic systems applied to the biological system
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Light-induced reactivation of O2-tolerant membrane-bound [Ni-Fe] hydrogenase from the hyperthermophilic bacterium Aquifex aeolicus under turnover conditions.
Physical Chemistry Chemical Physics, 2013Co-Authors: Alexandre Ciaccafava, Marie Thérèse Giudici-orticoni, Pascale Infossi, Cyrille Hamon, Valérie Marchi, Elisabeth LojouAbstract:We report the effect of UV-Vis light on the membrane-bound [Ni-Fe] hydrogenase from Aquifex aeolicus under turnover conditions. Using electrochemistry, we show a potential dependent light sensitivity and propose that a light-induced structural change of the [Ni-Fe] active site is related to an enhanced reactivation of the hydrogenase under illumination at high potentials.
Shigeyuki Yokoyama - One of the best experts on this subject based on the ideXlab platform.
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crystal structure of Aquifex aeolicus gene product aq1627 a putative phosphoglucosamine mutase reveals a unique c terminal end to end disulfide linkage
Molecular BioSystems, 2017Co-Authors: Upasana Sridharan, Shigeyuki Yokoyama, Seiki Kuramitsu, Thirumananseri Kumarevel, Karthe PonnurajAbstract:The Aq1627 gene from Aquifex aeolicus, a hyperthermophilic bacterium has been cloned and overexpressed in Escherichia coli. The protein was purified to homogeneity and its X-ray crystal structure was determined to 1.3 A resolution using multiple wavelength anomalous dispersion phasing. The structural and sequence analysis of Aq1627 is suggestive of a putative phosphoglucosamine mutase. The structural features of Aq1627 further indicate that it could belong to a new subclass of the phosphoglucosamine mutase family. Aq1627 structure contains a unique C-terminal end-to-end disulfide bond, which links two monomers and this structural information can be used in protein engineering to make proteins more stable in different applications.
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Crystal structure and in silico studies of dihydrodipicolinate synthase (DHDPS) from Aquifex aeolicus.
Extremophiles : life under extreme conditions, 2014Co-Authors: Upasana Sridharan, Shigeyuki Yokoyama, Seiki Kuramitsu, Thirumananseri Kumarevel, Akio Ebihara, Karthe PonnurajAbstract:Dihydrodipicolinate synthase (DHDPS, E.C.4.2.1.52) catalyzes the first committed step in the lysine biosynthetic pathway: the condensation of (S)-aspartate semialdehyde and pyruvate to form (4S)-4-hydroxy-2,3,4,5-tetrahydro-(2S)-dipicolinic acid. Since (S)-lysine biosynthesis does not occur in animals, DHDPS is an attractive target for rational antibiotic and herbicide design. Here, we report the crystal structure of DHDPS from a hyperthermophilic bacterium Aquifex aeolicus (AqDHDPS). l-Lysine is used as an important animal feed additive where the production is at the level of 1.5 million tons per year. The biotechnological manufacture of lysine has been going for more than 50 years which includes over synthesis and reverse engineering of DHDPS. AqDHDPS revealed a unique disulfide linkage which is not conserved in the homologues of AqDHDPS. In silico mutation of C139A and intermolecular ion-pair residues and the subsequent molecular dynamics simulation of the mutants showed that these residues are critical for the stability of AqDHDPS tetramer. MD simulations of AqDHDPS at three different temperatures (303, 363 and 393 K) revealed that the molecule is stable at 363 K. Thus, this structural and in silico study of AqDHDPS likely provides additional details towards the rational and structure-based design of hyper-l-lysine producing bacterial strains.
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crystal structure of trna m 1 a58 methyltransferase trmi from Aquifex aeolicus in complex with s adenosyl l methionine
Journal of Structural and Functional Genomics, 2014Co-Authors: Mitsuo Kuratani, Kazushige Katsura, Mikako Shirouzu, Yoshitaka Bessho, Ryohei Ishii, Tatsuo Yanagisawa, Michiyo Matsuno, Ryoko Ushikoshinakayama, Rie Shibata, Shigeyuki YokoyamaAbstract:The N1-methyladenosine residue at position 58 of tRNA is found in the three domains of life, and contributes to the stability of the three-dimensional L-shaped tRNA structure. In thermophilic bacteria, this modification is important for thermal adaptation, and is catalyzed by the tRNA m1A58 methyltransferase TrmI, using S-adenosyl-l-methionine (AdoMet) as the methyl donor. We present the 2.2 A crystal structure of TrmI from the extremely thermophilic bacterium Aquifex aeolicus, in complex with AdoMet. There are four molecules per asymmetric unit, and they form a tetramer. Based on a comparison of the AdoMet binding mode of A. aeolicus TrmI to those of the Thermus thermophilus and Pyrococcus abyssi TrmIs, we discuss their similarities and differences. Although the binding modes to the N6 amino group of the adenine moiety of AdoMet are similar, using the side chains of acidic residues as well as hydrogen bonds, the positions of the amino acid residues involved in binding are diverse among the TrmIs from A. aeolicus, T. thermophilus, and P. abyssi.
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crystal structure of type i 3 dehydroquinate dehydratase of Aquifex aeolicus suggests closing of active site flap is not essential for enzyme action
Biochemical and Biophysical Research Communications, 2013Co-Authors: Aribam Swarmistha Devi, Shigeyuki Yokoyama, Seiki Kuramitsu, Thirumananseri Kumarevel, Akio Ebihara, Karthe PonnurajAbstract:Structural analyses of enzymes involved in biosynthetic pathways that are present in micro-organisms, but absent from mammals (for example Shikimate pathway) are important in developing anti-microbial drugs. Crystal structure of the Shikimate pathway enzyme, type I 3-dehydroquinate dehydratase (3-DHQase) from the hyperthermophilic bacterium Aquifex aeolicus was solved both as an apo form and in complex with a ligand. The complex structure revealed an interesting structural difference when compared to other ligand-bound type I 3-DHQases suggesting that closure of the active site loop is not essential for catalysis. This provides new insights into the catalytic mechanism of type I 3-DHQases.
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crystallization and preliminary x ray crystallographic analysis of Aquifex aeolicus sela a bacterial selenocysteine synthase
Acta Crystallographica Section F-structural Biology and Crystallization Communications, 2012Co-Authors: Yuzuru Itoh, Shun-ichi Sekine, Shigeyuki YokoyamaAbstract:Selenocysteine (Sec), the 21st amino acid, is synthesized on its specific tRNA (tRNASec) via a multi-step process. In bacteria, tRNASec is ligated first with serine by seryl-tRNA synthetase, which is followed by Ser-to-Sec conversion by Sec synthase (SelA). To elucidate its structure and catalytic mechanism, Aquifex aeolicus SelA was crystallized. Although wild-type SelA crystals diffracted X-rays poorly (to up to 8 A resolution), the resolution was improved by introducing a quadruple point mutation targeting the loop regions and by methylating the lysine residues, which yielded 3.9 A resolution diffraction data from a full-length SelA crystal. Truncation of the N-terminal region (ΔN) also improved the resolution. A 3.3 A resolution data set for phase determination was obtained from a crystal of selenomethionine-substituted Lys-methylated SelA-ΔN.
Marietherese Giudiciorticoni - One of the best experts on this subject based on the ideXlab platform.
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spectroscopic characterization of the key catalytic intermediate ni c in the o2 tolerant nife hydrogenase i from Aquifex aeolicus evidence of a weakly bound hydride
Chemical Communications, 2012Co-Authors: Mariaeirini Pandelia, Pascale Infossi, Matthias Stein, Marietherese Giudiciorticoni, Wolfgang LubitzAbstract:Ni–C in the O2-tolerant hydrogenase I from Aquifex aeolicus binds a hydride weaker than that in O2-sensitive hydrogenases. This is in line with the enhanced light-sensitivity of Ni–C, greater lability of the hydride complex and increased catalytic redox potentials relevant to bio-H2 oxidation.
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the hyperthermophilic bacterium Aquifex aeolicus from respiratory pathways to extremely resistant enzymes and biotechnological applications
Advances in Microbial Physiology, 2012Co-Authors: Marianne Guiral, Laurence Prunetti, Pascale Infossi, Alexandre Ciaccafava, Elisabeth Lojou, Clement Aussignargues, Marianne Ilbert, Marietherese GiudiciorticoniAbstract:Abstract Aquifex aeolicus isolated from a shallow submarine hydrothermal system belongs to the order Aquificales which constitute an important component of the microbial communities at elevated temperatures. This hyperthermophilic chemolithoautotrophic bacterium, which utilizes molecular hydrogen, molecular oxygen, and inorganic sulfur compounds to flourish, uses the reductive TCA cycle for CO2 fixation. In this review, the intricate energy metabolism of A. aeolicus is described. As the chemistry of sulfur is complex and multiple sulfur species can be generated, A. aeolicus possesses a multitude of different enzymes related to the energy sulfur metabolism. It contains also membrane-embedded [NiFe] hydrogenases as well as oxidases enzymes involved in hydrogen and oxygen utilization. We have focused on some of these proteins that have been extensively studied and characterized as super-resistant enzymes with outstanding properties. We discuss the potential use of hydrogenases in an attractive H2/O2 biofuel cell in replacement of chemical catalysts. Using complete genomic sequence and biochemical data, we present here a global view of the energy-generating mechanisms of A. aeolicus including sulfur compounds reduction and oxidation pathways as well as hydrogen and oxygen utilization.
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the elusive third subunit iia of the bacterial b type oxidases the enzyme from the hyperthermophile Aquifex aeolicus
PLOS ONE, 2011Co-Authors: Laurence Prunetti, Myriam Brugna, Marietherese Giudiciorticoni, Régine Lebrun, Marianne GuiralAbstract:The reduction of molecular oxygen to water is catalyzed by complicated membrane-bound metallo-enzymes containing variable numbers of subunits, called cytochrome c oxidases or quinol oxidases. We previously described the cytochrome c oxidase II from the hyperthermophilic bacterium Aquifex aeolicus as a ba3-type two-subunit (subunits I and II) enzyme and showed that it is included in a supercomplex involved in the sulfide-oxygen respiration pathway. It belongs to the B-family of the heme-copper oxidases, enzymes that are far less studied than the ones from family A. Here, we describe the presence in this enzyme of an additional transmembrane helix “subunit IIa”, which is composed of 41 amino acid residues with a measured molecular mass of 5105 Da. Moreover, we show that subunit II, as expected, is in fact longer than the originally annotated protein (from the genome) and contains a transmembrane domain. Using Aquifex aeolicus genomic sequence analyses, N-terminal sequencing, peptide mass fingerprinting and mass spectrometry analysis on entire subunits, we conclude that the B-type enzyme from this bacterium is a three-subunit complex. It is composed of subunit I (encoded by coxA2) of 59000 Da, subunit II (encoded by coxB2) of 16700 Da and subunit IIa which contain 12, 1 and 1 transmembrane helices respectively. A structural model indicates that the structural organization of the complex strongly resembles that of the ba3 cytochrome c oxidase from the bacterium Thermus thermophilus, the IIa helical subunit being structurally the lacking N-terminal transmembrane helix of subunit II present in the A-type oxidases. Analysis of the genomic context of genes encoding oxidases indicates that this third subunit is present in many of the bacterial oxidases from B-family, enzymes that have been described as two-subunit complexes.
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stabilization role of a phenothiazine derivative on the electrocatalytic oxidation of hydrogen via Aquifex aeolicus hydrogenase at graphite membrane electrodes
Langmuir, 2010Co-Authors: Alexandre Ciaccafava, Pascale Infossi, Marietherese Giudiciorticoni, Elisabeth LojouAbstract:The [NiFe] membrane-bound hydrogenase from the microaerophilic, hyperthermophilic Aquifex aeolicus bacterium (Aa Hase) presents oxygen, carbon monoxide, and temperature resistances. Since it oxidizes hydrogen with high turnover, this enzyme is thus of particular interest for biotechnological applications, such as biofuel cells. Efficient immobilization of the enzyme onto electrodes is however a mandatory step. To gain further insight into the parameters governing the interfacial electron process, cyclic voltammetry was performed combining the use of a phenothiazine dye with a membrane electrode design where the enzyme is entrapped in a thin layer. In the absence of the phenothiazine dye, direct electron transfer (DET) for H2 oxidation is observed due to Aa Hase adsorbed onto the PG electrode. An unexpected loss of the catalytic current with time is however observed. The effect of toluidine blue O (TBO) on the catalytic process is first studied with TBO in solution. In addition to the expected mediated ele...
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the oxygen tolerant hydrogenase i from Aquifex aeolicus weakly interacts with carbon monoxide an electrochemical and time resolved ftir study
Biochemistry, 2010Co-Authors: Mariaeirini Pandelia, Pascale Infossi, Marietherese Giudiciorticoni, Wolfgang LubitzAbstract:The [NiFe] hydrogenase (Hase I) involved in the aerobic respiration of the hyperthermophilic bacterium Aquifex aeolicus shows increased oxygen tolerance and thermostability and can form very stable films on pyrolytic graphite electrodes. Oxygen-tolerant enzymes, like the ones from A. aeolicus and Ralstonia eutropha, are reported to be insensitive to CO inhibition. This is in contrast to known and well-characterized (oxygen-sensitive) hydrogenases, for which carbon monoxide is a competitive inhibitor. In this study, the interaction of Hase I from A. aeolicus with CO is examined using in situ infrared electrochemistry and time-resolved FTIR spectroscopy. We could observe the formation of a CO adduct state, a finding that set the grounds to investigate the affinity of an O2-tolerant enzyme for binding CO as well as the reversibility of this process. In the case of A. aeolicus, this extrinsic CO is shown to be weakly attached and the adduct state is light-sensitive at low temperatures. The energetic parameter...