Bibliografias temáticas / [4Fe-4S]2+

Literatura científica selecionada sobre o tema "[4Fe-4S]2+"

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Publicado: 20 de julho de 2024

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Artigos de revistas sobre o assunto "[4Fe-4S]2+"

Azam, Tamanna, Jonathan Przybyla-Toscano, Florence Vignols, Jérémy Couturier, Nicolas Rouhier e Michael K. Johnson. "[4Fe-4S] cluster trafficking mediated by Arabidopsis mitochondrial ISCA and NFU proteins". Journal of Biological Chemistry 295, n.º 52 (29 de outubro de 2020): 18367–78. http://dx.doi.org/10.1074/jbc.ra120.015726.

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Numerous iron-sulfur (Fe-S) proteins with diverse functions are present in the matrix and respiratory chain complexes of mitochondria. Although [4Fe-4S] clusters are the most common type of Fe-S cluster in mitochondria, the molecular mechanism of [4Fe-4S] cluster assembly and insertion into target proteins by the mitochondrial iron-sulfur cluster (ISC) maturation system is not well-understood. Here we report a detailed characterization of two late-acting Fe-S cluster-carrier proteins from Arabidopsis thaliana, NFU4 and NFU5. Yeast two-hybrid and bimolecular fluorescence complementation studies demonstrated interaction of both the NFU4 and NFU5 proteins with the ISCA class of Fe-S carrier proteins. Recombinant NFU4 and NFU5 were purified as apo-proteins after expression in Escherichia coli. In vitro Fe-S cluster reconstitution led to the insertion of one [4Fe-4S]2+ cluster per homodimer as determined by UV-visible absorption/CD, resonance Raman and EPR spectroscopy, and analytical studies. Cluster transfer reactions, monitored by UV-visible absorption and CD spectroscopy, showed that a [4Fe-4S]2+ cluster-bound ISCA1a/2 heterodimer is effective in transferring [4Fe-4S]2+ clusters to both NFU4 and NFU5 with negligible back reaction. In addition, [4Fe-4S]2+ cluster-bound ISCA1a/2, NFU4, and NFU5 were all found to be effective [4Fe-4S]2+ cluster donors for maturation of the mitochondrial apo-aconitase 2 as assessed by enzyme activity measurements. The results demonstrate rapid, unidirectional, and quantitative [4Fe-4S]2+ cluster transfer from ISCA1a/2 to NFU4 or NFU5 that further delineates their respective positions in the plant ISC machinery and their contributions to the maturation of client [4Fe-4S] cluster-containing proteins.

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Duan, Xuewu, Juanjuan Yang, Binbin Ren, Guoqiang Tan e Huangen Ding. "Reactivity of nitric oxide with the [4Fe–4S] cluster of dihydroxyacid dehydratase from Escherichia coli". Biochemical Journal 417, n.º 3 (16 de janeiro de 2009): 783–89. http://dx.doi.org/10.1042/bj20081423.

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Although the NO (nitric oxide)-mediated modification of iron–sulfur proteins has been well-documented in bacteria and mammalian cells, specific reactivity of NO with iron–sulfur proteins still remains elusive. In the present study, we report the first kinetic characterization of the reaction between NO and iron–sulfur clusters in protein using the Escherichia coli IlvD (dihydroxyacid dehydratase) [4Fe–4S] cluster as an example. Combining a sensitive NO electrode with EPR (electron paramagnetic resonance) spectroscopy and an enzyme activity assay, we demonstrate that NO is rapidly consumed by the IlvD [4Fe–4S] cluster with the concomitant formation of the IlvD-bound DNIC (dinitrosyl–iron complex) and inactivation of the enzyme activity under anaerobic conditions. The rate constant for the initial reaction between NO and the IlvD [4Fe–4S] cluster is estimated to be (7.0±2.0)×106 M−2·s−1 at 25 °C, which is approx. 2–3 times faster than that of the NO autoxidation by O2 in aqueous solution. Addition of GSH failed to prevent the NO-mediated modification of the IlvD [4Fe–4S] cluster regardless of the presence of O2 in the medium, further suggesting that NO is more reactive with the IlvD [4Fe–4S] cluster than with GSH or O2. Purified aconitase B [4Fe–4S] cluster from E. coli has an almost identical NO reactivity as the IlvD [4Fe–4S] cluster. However, the reaction between NO and the endonuclease III [4Fe–4S] cluster is relatively slow, apparently because the [4Fe–4S] cluster in endonuclease III is less accessible to solvent than those in IlvD and aconitase B. When E. coli cells containing recombinant IlvD, aconitase B or endonuclease III are exposed to NO using the Silastic tubing NO delivery system under aerobic and anaerobic conditions, the [4Fe–4S] clusters in IlvD and aconitase B, but not in endonuclease III, are efficiently modified forming the protein-bound DNICs, confirming that NO has a higher reactivity with the [4Fe–4S] clusters in IlvD and aconitase B than with O2 or GSH. The results suggest that the iron–sulfur clusters in proteins such as IlvD and aconitase B may constitute the primary targets of the NO cytotoxicity under both aerobic and anaerobic conditions.

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Sutton, Victoria R., Erin L. Mettert, Helmut Beinert e Patricia J. Kiley. "Kinetic Analysis of the Oxidative Conversion of the [4Fe-4S]2+ Cluster of FNR to a [2Fe-2S]2+ Cluster". Journal of Bacteriology 186, n.º 23 (1 de dezembro de 2004): 8018–25. http://dx.doi.org/10.1128/jb.186.23.8018-8025.2004.

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ABSTRACT The ability of FNR to sense and respond to cellular O2 levels depends on its [4Fe-4S]2+ cluster. In the presence of O2, the [4Fe-4S]2+ cluster is converted to a [2Fe-2S]2+ cluster, which inactivates FNR as a transcriptional regulator. In this study, we demonstrate that ∼2 Fe2+ ions are released from the reaction of O2 with the [4Fe-4S]2+ cluster. Fe2+ release was then used as an assay of reaction progress to investigate the rate of [4Fe-4S]2+ to [2Fe-2S]2+ cluster conversion in vitro. We also found that there was no detectable difference in the rate of O2-induced cluster conversion for FNR free in solution compared to its DNA-bound form. In addition, the rate of FNR inactivation was monitored in vivo by measuring the rate at which transcriptional regulation by FNR is lost upon the exposure of cells to O2; a comparison of the in vitro and in vivo rates of conversion suggests that O2-induced cluster conversion is sufficient to explain FNR inactivation in cells. FNR protein levels were also compared for cells grown under aerobic and anaerobic conditions.

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George, S. J., F. A. Armstrong, E. C. Hatchikian e A. J. Thomson. "Electrochemical and spectroscopic characterization of the conversion of the 7Fe into the 8Fe form of ferredoxin III from Desulfovibrio africanus. Identification of a [4Fe–4S] cluster with one non-cysteine ligand". Biochemical Journal 264, n.º 1 (15 de novembro de 1989): 275–84. http://dx.doi.org/10.1042/bj2640275.

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Desulfovibrio africanus ferredoxin III is a protein (Mr 6585) containing one [3Fe-4S]1+,0 and one [4Fe-4S]2+,1+ core cluster when aerobically isolated. The amino acid sequence contains only seven cysteine residues, the minimum required to ligand these two clusters. Cyclic voltammery by means of direct electrochemistry at a pyrolytic-graphite-‘edge’ electrode promoted by neomycin shows that, when reduced, the [3Fe-4S]0 centre reacts rapidly with Fe(II) ion to form a [4Fe-4S]2+ cluster. The latter, which can be reduced at a redox potential similar to that of the other [4Fe-4S] cluster, must include non-thiolate ligation. We propose that the carboxylate side chain of aspartic acid-14 is the most likely candidate, since this amino acid occupies the position of a cysteine residue in the sequence typical of an 8Fe ferredoxin. The magnetic properties at liquid-He temperature of this novel cluster, studied by low-temperature magnetic-c.d. and e.p.r. spectroscopy, are diamagnetic in the oxidized state and S = 3/2 in the one-electron-reduced state. This cluster provides a plausible model for the ligation states of the [4Fe-4S]1+ core in the S = 3/2 cluster of the iron protein of nitrogenase and in Bacillus subtilis glutamine:phosphoribosyl pyrophosphate amidotransferase.

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Azam, Tamanna, Jonathan Przybyla-Toscano, Florence Vignols, Jérémy Couturier, Nicolas Rouhier e Michael K. Johnson. "The Arabidopsis Mitochondrial Glutaredoxin GRXS15 Provides [2Fe-2S] Clusters for ISCA-Mediated [4Fe-4S] Cluster Maturation". International Journal of Molecular Sciences 21, n.º 23 (3 de dezembro de 2020): 9237. http://dx.doi.org/10.3390/ijms21239237.

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Iron-sulfur (Fe-S) proteins are crucial for many cellular functions, particularly those involving electron transfer and metabolic reactions. An essential monothiol glutaredoxin GRXS15 plays a key role in the maturation of plant mitochondrial Fe-S proteins. However, its specific molecular function is not clear, and may be different from that of the better characterized yeast and human orthologs, based on known properties. Hence, we report here a detailed characterization of the interactions between Arabidopsis thaliana GRXS15 and ISCA proteins using both in vivo and in vitro approaches. Yeast two-hybrid and bimolecular fluorescence complementation experiments demonstrated that GRXS15 interacts with each of the three plant mitochondrial ISCA1a/1b/2 proteins. UV-visible absorption/CD and resonance Raman spectroscopy demonstrated that coexpression of ISCA1a and ISCA2 resulted in samples with one [2Fe-2S]2+ cluster per ISCA1a/2 heterodimer, but cluster reconstitution using as-purified [2Fe-2S]-ISCA1a/2 resulted in a [4Fe-4S]2+ cluster-bound ISCA1a/2 heterodimer. Cluster transfer reactions monitored by UV-visible absorption and CD spectroscopy demonstrated that [2Fe-2S]-GRXS15 mediates [2Fe-2S]2+ cluster assembly on mitochondrial ferredoxin and [4Fe-4S]2+ cluster assembly on the ISCA1a/2 heterodimer in the presence of excess glutathione. This suggests that ISCA1a/2 is an assembler of [4Fe-4S]2+ clusters, via two-electron reductive coupling of two [2Fe-2S]2+ clusters. Overall, the results provide new insights into the roles of GRXS15 and ISCA1a/2 in effecting [2Fe-2S]2+ to [4Fe-4S]2+ cluster conversions for the maturation of client [4Fe-4S] cluster-containing proteins in plants.

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Dridge, Elizabeth J., Carys A. Watts, Brian J. N. Jepson, Kirsty Line, Joanne M. Santini, David J. Richardson e Clive S. Butler. "Investigation of the redox centres of periplasmic selenate reductase from Thauera selenatis by EPR spectroscopy". Biochemical Journal 408, n.º 1 (29 de outubro de 2007): 19–28. http://dx.doi.org/10.1042/bj20070669.

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Periplasmic SER (selenate reductase) from Thauera selenatis is classified as a member of the Tat (twin-arginine translocase)-translocated (Type II) molybdoenzymes and comprises three subunits each containing redox cofactors. Variable-temperature X-band EPR spectra of the purified SER complex showed features attributable to centres [3Fe–4S]1+, [4Fe–4S]1+, Mo(V) and haem-b. EPR-monitored redox-potentiometric titration of the SerABC complex (SerA–SerB–SerC, a hetero-trimetric complex of αβγ subunits) revealed that the [3Fe–4S] cluster (FS4, iron-sulfur cluster 4) titrated as n=1 Nernstian component with a midpoint redox potential (Em) of +118±10 mV for the [3Fe–4S]1+/0 couple. A [4Fe–4S]1+ cluster EPR signal developed over a range of potentials between 300 and −200 mV and was best fitted to two sequential Nernstian n=1 curves with midpoint redox potentials of +183±10 mV (FS1) and −51±10 mV (FS3) for the two [4Fe–4S]1+/2+ cluster couples. Upon further reduction, the observed signal intensity of the [4Fe–4S]1+ cluster decreases. This change in intensity can again be fitted to an n=1 Nernstian component with a midpoint potential (Em) of about −356 mV (FS2). It is considered likely that, at low redox potential (Em less than −300 mV), the remaining oxidized cluster is reduced (spin S=1/2) and strongly spin-couples to a neighbouring [4Fe–4S]1+ cluster rendering both centres EPR-silent. The involvement of both [3Fe–4S] and [4Fe–4S] clusters in electron transfer to the active site of the periplasmic SER was demonstrated by the re-oxidation of the clusters under anaerobic selenate turnover conditions. Attempts to detect a high-spin [4Fe–4S] cluster (FS0) in SerA at low temperature (5 K) and high power (100 mW) were unsuccessful. The Mo(V) EPR recorded at 60 K, in samples poised at pH 6.0, displays principal g values of g3∼1.999, g2∼1.996 and g1∼1.965 (gav 1.9867). The dominant features at g2 and g3 are not split, but hyperfine splitting is observed in the g1 region of the spectrum and can be best simulated as arising from a single proton with a coupling constant of A1 (1H)=1.014 mT. The presence of the haem-b moiety in SerC was demonstrated by the detection of a signal at g∼3.33 and is consistent with haem co-ordinated by methionine and lysine axial ligands. The combined evidence from EPR analysis and sequence alignments supports the assignment of the periplasmic SER as a member of the Type II molybdoenzymes and provides the first spectro-potentiometric insight into an enzyme that catalyses a key reductive reaction in the biogeochemical selenium cycle.

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BUSCH, Johanneke L. H., Jacques L. BRETON, Barry M. BARTLETT, Fraser A. ARMSTRONG, Richard JAMES e Andrew J. THOMSON. "[3Fe-4S]↔[4Fe-4S] cluster interconversion in Desulfovibrio africanus ferredoxin III: properties of an Asp14→Cys mutant". Biochemical Journal 323, n.º 1 (1 de abril de 1997): 95–102. http://dx.doi.org/10.1042/bj3230095.

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The 8Fe ferredoxin III from Desulfovibrio africanus is a monomeric protein which contains two [4Fe-4S]2+/1+ clusters, one of which is labile and can readily and reversibly lose one Fe under oxidative conditions to yield a [3Fe-4S]1+/0 cluster. This 4Fe cluster has an S = 3/2 ground spin state instead of S = 1/2 in the reduced +1 state [George, Armstrong, Hatchikian and Thomson (1989) Biochem. J.264, 275-284]. The co-ordination to this cluster is unusual in that an aspartate (Asp14, D14) is found where a cysteine residue normally occurs. Using a mutant protein obtained from the overexpression in Escherichia coli of a synthetic gene in which Asp14, the putative ligand to the removable Fe, has been changed to Cys, we have studied the cluster interconversion properties of the labile cluster. Analysis by EPR and magnetic-circular-dichroism spectroscopies showed that the Asp14 → Cys (D14C) mutant contains two [4Fe-4S]2+/1+ clusters, both with S = 1/2 in the reduced state. Also, unlike in native 8Fe D. africanus ferredoxin III, the 4Fe ↔ 3Fe cluster interconversion reaction was found to be sluggish and did not go to completion. It is inferred that the reversibility of the reaction in the native protein is due to the presence of the aspartate residue at position 14 and that this residue might protect the [3Fe-4S] cluster from further degradation.

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Smith, Eugene T., Dennis W. Bennett e Benjamin A. Feinberg. "Redox properties of 2[4Fe4S] ferredoxins". Analytica Chimica Acta 251, n.º 1-2 (outubro de 1991): 27–33. http://dx.doi.org/10.1016/0003-2670(91)87111-j.

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Roland, Mélanie, Jonathan Przybyla-Toscano, Florence Vignols, Nathalie Berger, Tamanna Azam, Loick Christ, Véronique Santoni et al. "The plastidial Arabidopsis thaliana NFU1 protein binds and delivers [4Fe-4S] clusters to specific client proteins". Journal of Biological Chemistry 295, n.º 6 (6 de janeiro de 2020): 1727–42. http://dx.doi.org/10.1074/jbc.ra119.011034.

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Proteins incorporating iron–sulfur (Fe-S) co-factors are required for a plethora of metabolic processes. Their maturation depends on three Fe-S cluster assembly machineries in plants, located in the cytosol, mitochondria, and chloroplasts. After de novo formation on scaffold proteins, transfer proteins load Fe-S clusters onto client proteins. Among the plastidial representatives of these transfer proteins, NFU2 and NFU3 are required for the maturation of the [4Fe-4S] clusters present in photosystem I subunits, acting upstream of the high-chlorophyll fluorescence 101 (HCF101) protein. NFU2 is also required for the maturation of the [2Fe-2S]-containing dihydroxyacid dehydratase, important for branched-chain amino acid synthesis. Here, we report that recombinant Arabidopsis thaliana NFU1 assembles one [4Fe-4S] cluster per homodimer. Performing co-immunoprecipitation experiments and assessing physical interactions of NFU1 with many [4Fe-4S]-containing plastidial proteins in binary yeast two-hybrid assays, we also gained insights into the specificity of NFU1 for the maturation of chloroplastic Fe-S proteins. Using bimolecular fluorescence complementation and in vitro Fe-S cluster transfer experiments, we confirmed interactions with two proteins involved in isoprenoid and thiamine biosynthesis, 1-hydroxy-2-methyl-2-(E)-butenyl-4-diphosphate synthase and 4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate synthase, respectively. An additional interaction detected with the scaffold protein SUFD enabled us to build a model in which NFU1 receives its Fe-S cluster from the SUFBC2D scaffold complex and serves in the maturation of specific [4Fe-4S] client proteins. The identification of the NFU1 partner proteins reported here more clearly defines the role of NFU1 in Fe-S client protein maturation in Arabidopsis chloroplasts among other SUF components.

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Stripp, Sven T., Jonathan Oltmanns, Christina S. Müller, David Ehrenberg, Ramona Schlesinger, Joachim Heberle, Lorenz Adrian, Volker Schünemann, Antonio J. Pierik e Basem Soboh. "Electron inventory of the iron-sulfur scaffold complex HypCD essential in [NiFe]-hydrogenase cofactor assembly". Biochemical Journal 478, n.º 17 (7 de setembro de 2021): 3281–95. http://dx.doi.org/10.1042/bcj20210224.

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The [4Fe-4S] cluster containing scaffold complex HypCD is the central construction site for the assembly of the [Fe](CN)2CO cofactor precursor of [NiFe]-hydrogenase. While the importance of the HypCD complex is well established, not much is known about the mechanism by which the CN− and CO ligands are transferred and attached to the iron ion. We report an efficient expression and purification system producing the HypCD complex from E. coli with complete metal content. This enabled in-depth spectroscopic characterizations. The results obtained by EPR and Mössbauer spectroscopy demonstrate that the [Fe](CN)2CO cofactor and the [4Fe-4S] cluster of the HypCD complex are redox active. The data indicate a potential-dependent interconversion of the [Fe]2+/3+ and [4Fe-4S]2+/+ couple, respectively. Moreover, ATR FTIR spectroscopy reveals potential-dependent disulfide formation, which hints at an electron confurcation step between the metal centers. MicroScale thermophoresis indicates preferable binding between the HypCD complex and its in vivo interaction partner HypE under reducing conditions. Together, these results provide comprehensive evidence for an electron inventory fit to drive multi-electron redox reactions required for the assembly of the CN− and CO ligands on the scaffold complex HypCD.

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Teses / dissertações sobre o assunto "[4Fe-4S]2+"

Davasse, Valérie. "Ingénierie de la ferredoxine 2[4Fe-4S] de Clostridium pasteurianum". Grenoble 1, 1993. http://www.theses.fr/1993GRE10135.

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La ferredoxine 24fe-4s de la bacterie anaerobie clostridium pasteurianum est une proteine de 55 acides amines au caractere acide. Ses deux centres 4fe-4s sont lies a la chaine polypeptidique par l'intermediaire de 8 residus cysteine. Elle tient un role central de transporteur d'electrons dans le metabolisme de clostridium pasteurianum. Un gene codant pour cette ferredoxine a ete entierement synthetise a partir de 18 oligonucleotides. L'expression de ce gene chez escherichia coli produit une proteine recombinante totalement identique a la ferredoxine native. Le remplacement modulaire de segments de ce gene synthetique a permis d'obtenir des genes codant pour des formes modifiees de la ferredoxine au niveau de 5 acides carboxyliques en positions 6, 17, 33, 35 et 39, des prolines 19 et 48, de l'isoleucine 23 et de la cysteine 18. Le role des residus charges parait assez limite dans la reconnaissance de la ferredoxine avec deux de ses partenaires physiologiques lors du transfert d'electrons. Par contre, lorsque les changements touchent des residus proches, et donc l'environnement, des centres 4fe-4s, l'activite biologique est affectee. Le remplacement de la cysteine 18, ligand d'un des clusters, par une histidine ou une tyrosine conduit a des proteines pouvant remplacer la ferredoxine comme transporteur d'electrons entre deux de ses partenaires mais avec une cinetique tres particuliere

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Lenormand-Foucaut, Alix. "Modélisation chimique de protéines fer-soufre à haut potentiel : synthèses et caractérisations physico-chimiques de nouveaux agrégats à ligands thiolates encombrés dans les états (4Fe-4S)2+ et (4Fe-4S)3+". Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10056.

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Cette these se situe dans le cadre des modelisations chimiques de proteines fer-soufre, plus particulierement les proteines fer-soufre a haut potentiel (hipip). L'objectif est de synthetiser des centres 4fe-4s dans les deux etats d'oxydation physiologiques 4fe-4s#2+ et 4fe-4s#3+ et de les caracteriser d'un point de vue physico-chimique. L'hypothese a partir de laquelle le sujet a ete aborde consiste a supposer qu'il est necessaire d'etablir une zone steriquement encombree et hydrophobe autour de l'agregat afin de proteger le centre 4fe-4s#3+ d'une degradation oxydante. Pratiquement, un tel environnement encombre et hydrophobe a ete realise grace a l'utilisation de ligands thiolates riches en noyaux aromatiques et tres encombres. Pour chaque ligand utilise, le centre 4fe-4s#2+ a ete synthetise et caracterise par les spectroscopies uv-visible, rmn et mossbauer, et l'etude de sa susceptibilite magnetique a aussi ete effectuee. Dans un deuxieme temps, des etudes d'oxydation sont realisees sur ces nouveaux composes modeles 4fe-4s#2+ dans le but d'obtenir des centres 4fe-4s#3+. Des phenythiolates d'une part et des benzylhtiolates d'autre part, tous tres hydrophobes, ont ete utilises comme ligands. Dans chacun des cas, un nouveau modele de hipip a ete obtenu et completement caracterise dans les deux etats redox. Celui avec le ligand de type benzylthiolate est un meilleur modele chimique de ces proteines car il utilise des ligands plus biomimetiques. Par ailleurs, l'influence exercee par l'encombrement sterique a ete etudiee de facon systematique. En utilisant une serie de ligands encombres de facon croissante, il a pu etre montre tres clairement que la presence d'un environnement encombre (et toujours tres hydrophobe) au voisinage immediat de l'agregat assure la protection du centre 4fe-4s#3+ vis-a-vis des degradations ulterieures. L'ensemble des resultats obtenus autorisent a conclure sur la validite de l'hypothese de depart, laquelle preconisait l'emploi de ligands encombres pour l'obtention de tels modeles stables. Ce travail permet alors egalement de confirmer l'hypothese sur les proteines qui consiste a dire que l'hydrophobicite est un critere fondamental pour qu'une proteine a 4fe-4s fonctionne comme une hipip plutot que comme une ferredoxine

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Maerker, Claudia. "Die zwei metabolischen Funktionen der Aconitase AcoA aus Aspergillus nidulans Aconitase-Aktivität im (4Fe-4S)2+ und Methylisocitrat-Dehydratase-Aktivität im (3Fe-4S)+-Zustand /". [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=98410786X.

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Chan, Alice. "Structure et Mécanisme de la Quinolinate Synthase : enzyme à centre [4Fe-4S]2+ et cible d'agents antibactériens". Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENV036.

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Le Nicotinamide Adénine Dinucléotide (NAD) est un cofacteur clé du métabolisme cellulaire. Synthétisé à partir d'acide quinolinique (QA) chez tous les organismes vivants, la biosynthèse du QA diffère entre les eucaryotes et les procaryotes. Chez les eucaryotes, il est produit à partir de L-tryptophane alors que chez les procaryotes et les plantes, il est synthétisé par l'action concertée de deux enzymes: la L-aspartate oxydase (NadB) qui permet la formation d'iminoaspartate (IA) à partir de L-aspartate et la quinolinate synthase (NadA) qui permet la condensation de deux molécules, la dihydroxyacétone-phosphate (DHAP) et l'iminoaspartate, pour former l'acide quinolinique. En plus de cette voie dite « de novo », la plupart des organismes possèdent une voie de secours qui produit le NAD à partir de niacine provenant de l'alimentation ou de la dégradation du NAD. Chez certains pathogènes tels que Mycobacterium leprae et Helicobacter pylori, cette voie de secours n'existe pas. Ceci fait de NadA une cible particulièrement attractive pour la conception d'antibactériens et ceci d'autant plus qu'elle est absente chez l'homme.NadA est la seule enzyme de la voie de biosynthèse de novo du NAD dont le mécanisme moléculaire et la structure tridimensionnelle sous forme active (avec son centre [4Fe-4S]2+) sont inconnus. Grâce à l'utilisation d'analogues de substrats ou d'intermédiaires réactionnels, nous avons pu non seulement avancer dans l'élucidation du mécanisme moléculaire de NadA et notamment dans la compréhension du rôle du centre [4Fe-4S]2+ dans la catalyse mais en plus, nous avons été en mesure de proposer un 1er inhibiteur in vitro et in vivo de NadA : l'acide 4,5 Dithiohydroxyphtalique (DTHPA). Le DTHPA nous a fourni de bonnes bases pour la conception d'inhibiteurs puissants et spécifiques de NadA grâce à une étude Structure-Activité. Par ailleurs, nous avons résolu la 1ère structure aux rayons X de NadA sous forme holoprotéine dont les données structurales nous ont grandement aidé dans la compréhension du mécanisme de NadA
The Nicotinamide Adenine Dinucleotide (NAD) is a key cofactor essential for cellular metabolism. Synthesized from quinolinic acid (QA) in all living organisms, NAD biosynthesis is different between eucaryotes and procaryotes. Indeed, most of eukaryotes produce QA from L-tryptophan, whereas most of prokaryotes and plants synthesize QA by the concerted action of 2 enzymes: L-aspartate oxydase (NadB), an FAD enzyme, which catalyzes L-Aspartate oxidation to form iminoaspartate (IA) while quinolinate synthetase (NadA) allows condensation between IA and Dihydroxyacetone Phosphate (DHAP) to produce QA. Besides this « de novo » pathway, most eukaryotes and some bacteriae have a salvage pathway which allows NAD synthesis from nutrients and metabolites of NAD degradation in order to maintain a correct pool of NAD in the cell. However, some pathogens like Mycobacterium leprae, Helicobacter pylori do not possess this pathway. As a consequence, NadA represents a very attractive target for designing specific antibacterial agents since it does not exist in Human.NadA is the only metalloenzyme of NAD de novo biosynthesis whose molecular mechanism and tridimensional structure with its [4Fe-4S]2+ cluster are unknown. Using substrate and intermediate analogues, we have been able to understand better NadA mechanism, especially [4Fe-4S]2+ cluster role in catalysis. Moreover, we proposed the first in vitro and in vivo inhibitor of NadA : the 4,5 Dithiohydroxyphtalic Acid (DTHPA) which gave us basis to design powerful and specific NadA inhibitors thanks to a structure-activity relationship study. Besides, we resolved the first X-rays structure of NadA under its holoprotein form. Datas we extracted from it helped us greatly to understand NadA mechanism

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Lawson, Daku Latévi Maxime. "Étude de la protéine fer-soufre à haut potentiel de Chromatium vinosum et de composés modèles : structures électroniques dans les états d'oxydation [4Fe-4S]2+ et [4Fe-4S]3+ en relation avec les données d'aimantation et des mesures optiques à température variable". Grenoble 1, 1999. http://www.theses.fr/1999GRE10072.

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Les centres fer-soufre sont des groupements metalliques presents dans une grande variete de proteines ou ils assurent des fonctions tres diverses. Depuis plus d'une vingtaine d'annees, la description de leurs proprietes a suscite une somme considerable de travaux, mais la comprehension de leur structure electronique se heurte a plusieurs difficultes liees a la presence d'etats de valence mixte fe i i et fe i i i et a leur delocalisation sur plusieurs sites fe. Dans ce contexte, nous avons entrepris une etude systematique des proprietes magnetiques des centres 4fe4s 2 + / 3 + presents dans la proteine a haut potentiel de chromatium vinosum et de plusieurs composes modeles. Nous avons choisi d'effectuer des mesures d'aimantation et de spectroscopie optique sur une gamme etendue de temperatures. Ce qui nous a permis d'obtenir des informations structurales tout a fait complementaires de celles obtenues par d'autres techniques spectroscopiques : mosbauer, rmn, rpe. Nous avons pu demontrer que dans les systemes 4fe4s 2 +, la modelisation par paires en symetrie d 2 d et une description des interactions en termes d'interactions d'echange et de double, echange permettent de rendre compte des resultats obtenus. En revanche, dans le cas des systemes 4fe4s 3 +, la description n'a pu etre obtenue que de maniere approximative. Pour ces systemes, nous avons entrepris de raffiner leur description en prenant en compte le phenomene de couplage vibronique, et nous avons obtenu des resultats tres prometteurs.

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Jobelius, Hannah. "Etude de la métalloenzyme IspH, une cible pour le développement de nouveaux agents antibactériens". Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAF004.

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IspH est la dernière enzyme de la voie du méthylérythritol phosphate qui produit les deux précurseurs nécessaires à la biosynthèse de tous les isoprénoïdes. Cette métalloenzyme est essentielle à la survie de nombreux microorganismes dont des bactéries pathogènes et le parasite responsable du paludisme. Etant absente chez l’humain, IspH est une cible de choix pour le développement de nouveaux agents antimicrobiens. En utilisant une approche pluridisciplinaire combinant biologie moléculaire, enzymologie, spectroscopies Raman, Mössbauer et cristallographie, l’objectif de cette thèse était d’étudier le mécanisme d’IspH et plus particulièrement les paramètres qui gouvernent la formation des deux produits dans un ratio défini. Plusieurs mutants d’IspH d’E coli ont été produits, étudiés et caractérisés, et les résultats ont mis en évidence des acides aminés importants pour l’activité enzymatique et aussi pour maintenir le ratio des deux produits. Lors des études biophysiques, ces mutants ont révélé des différences au niveau de leur cofacteur, un centre [4Fe4S]2+, et de leur façon de lier le substrat par rapport à l’enzyme de type sauvage. IspH a pour la première fois été étudiée par spectroscopie Raman et une analyse détaillée a été menée
IspH is the last enzyme of the methylerythritol phosphate pathway which produces the two precursors needed for the biosynthesis of all isoprenoids. This metalloenzyme is essential for the survival of many microorganisms, among them pathogenic bacteria and the parasite responsible for malaria. Being absent in humans, IspH is a suitable target for the development of novel antimicrobial agents. Using a multidisciplinary approach combining molecular biology, enzymology, Raman and Mössbauer spectroscopy, and crystallography, the objective of this thesis was to understand the mechanism of IspH and especially the formation of the two products in a defined ratio. Several mutants were produced, studied and characterized, and the results shed light on some amino acids which are important for the enzyme activity and for maintaining the ratio of the two products. During biophysical studies, these mutants revealed differences in their cofactor, a [4Fe4S]2+ cluster, and in their way to bind the substrate as compared to the wild type enzyme. IspH has for the first time been studied using Raman spectroscopy and a detailed analysis was conducted

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Hinkley, Glen Thomas. "Ligand effects on the reduction potential of the [4Fe-4S] cluster in Lysine 2, 3-aminomutase". 2005. http://catalog.hathitrust.org/api/volumes/oclc/64033202.html.

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Lin, Zong-Sian, e 林宗憲. "Transformation of Dinitrosyl Iron Complexes (DNICs) [(NO)2Fe(SR)2]– (R = Et, Ph) into [4Fe-4S] Clusters [Fe4S4(SPh)4]2–". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/43834688213528712968.

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Maerker, Claudia [Verfasser]. "Die zwei metabolischen Funktionen der Aconitase AcoA aus Aspergillus nidulans : Aconitase-Aktivität im (4Fe-4S)2+ und Methylisocitrat-Dehydratase-Aktivität im (3Fe-4S)+-Zustand / von Claudia Maerker". 2007. http://d-nb.info/98410786X/34.

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Romano, Christine Anne. "DNA-Mediated Charge Transfer Between [4Fe-4S] Cluster Glycosylases". Thesis, 2011. https://thesis.library.caltech.edu/6277/2/Chapter_2.pdf.

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The work performed herein describes three proteins: Uracil DNA glycosylase (UDG) from Archaeoglobus fulgidus, MutY, and Endonuclease III (EndoIII) from Escherichia coli. They are DNA repair glycosylases that contain [4Fe-4S] clusters. While the catalytic mechanisms of many BER enzymes have been studied in detail, questions remain about how these enzymes search the vast amount of cellular DNA to find their substrates, and why some require a [4Fe-4S] cluster. The iron-sulfur cluster is not necessary for catalysis, and it only displays a physiologically relevant midpoint potential when bound to DNA. We have proposed that UDG, MutY, and EndoIII use their [4Fe-4S] clusters to participate in DNA-mediated charge transport (CT), and that these proteins mediate long-range electrochemical signaling in order to detect DNA damage.

This scheme for DNA damage detection assumes that CT occurs efficiently between the DNA helix and the [4Fe-4S] cluster of the bound protein. In order for efficient CT to occur, a pathway of amino acids must be present that facilitates CT between the DNA and the iron-sulfur cluster. For each of the enzymes mentioned, this pathway was explored through mutagenesis. In UDG, MutY, and EndoIII, several amino acids thought to be important for CT were mutated and the resulting proteins were characterized biochemically. Their CT capabilities were analyzed by cyclic voltammetry on DNA-modified electrodes. In these experiments, the mutants’ signal intensities were quantified and compared to those of wild-type enzyme. An attenuated signal relative to wild-type protein may indicate that the mutant is deficient in CT and that the targeted amino acid is part of the protein-DNA CT pathway in the native enzyme. Many mutants were also screened by enzymatic assays and circular dichroism spectroscopy to further characterize their DNA-binding properties and structural stability.

The A. fulgidus UDG mutants examined, C17H, C85S, and C101S, all contained mutations in the cysteine residues that ligate the [4Fe-4S] cluster. These mutants were designed to determine how the iron-sulfur cluster coordination environment affects protein-DNA CT. The mutants exhibited varying signal strengths relative to WT UDG on DNA-modified electrodes. C85S produced a weaker signal, indicating a CT deficiency. The signal intensity from C101S was within error of that of WT, and the signal from C17H was larger than that of WT, possibly indicating that this mutant is less structurally stable than WT UDG.

In E. coli MutY, position Y82 aligns with Y165 in MUTYH, a residue in which mutations have been found in many colorectal cancer patients. To better understand the correlation between protein-DNA CT and colorectal cancer, the MutY mutants Y82C and Y82L were prepared and characterized. Y82C exhibited a CT deficiency relative to WT MutY, whereas Y82L did not. These data indicate that Y82 forms part of the CT pathway in native E. coli MutY, but that other long-chain amino acids, such as leucine, can also mediate CT efficiently at this position.

Several different mutants of E. coli EndoIII were examined. First, the Y82 position was targeted, since the aligning MUTYH residue has been found mutated in colorectal cancer patients and because this residue is located near the protein-DNA interface. Five mutations were made at or near the Y82 position, and their cyclic voltammetry signals demonstrated that aromatic amino acids best mediate CT at this position. Other residues towards the interior of the protein, Y75, Y55, and F30 were also mutated to alanines. These mutants exhibited CT deficiencies, implicating the residues as part of a potential CT pathway. Residues W178 and Y185, located near the [4Fe-4S] cluster of EndoIII, were also mutated to alanines. The resulting mutants produced larger signals than that of WT EndoIII. These mutants were later shown by circular dichroism spectroscopy to be less stable structurally than WT EndoIII. All of the mutants mentioned exhibited enzymatic properties similar to those of WT, suggesting that they are able to bind DNA and excise damage nucleobases as well as the native enzyme. Several of these mutants were also used in a mutagenesis-based experiment to assay how EndoIII variants help MutY search for DNA lesions, although data from these experiments showed no significant differences in mutation rate between strains expressing different EndoIII variants.

In total, the mutagenesis studies performed here helped determine the characteristics of BER enzymes that enable them to mediate DNA-protein CT. All these enzymes must contain a stable, well-protected metallocluster that charge can access through a series of CT-facilitating amino acids. In discovering several residues important for protein-DNA CT in UDG, MutY, and EndoIII, we have strengthened support for the hypothesis that these enzymes facilitate DNA-mediated CT in vivo. These enzymes may in fact be part of a much larger array of redox-active DNA-binding proteins that communicate electrochemically to help each other detect and repair DNA lesions inside the cell.

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Capítulos de livros sobre o assunto "[4Fe-4S]2+"

Bethanis, Kostas, Petros Giastas, Trias Thireou e Vassilis Atlamazoglou. "Macromolecular Crystallographic Computing". In Biocomputation and Biomedical Informatics, 1–36. IGI Global, 2010. http://dx.doi.org/10.4018/978-1-60566-768-3.ch001.

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Structural genomics or structural proteomics can be defined as the quest to obtain the three-dimensional structures of all proteins. Single-crystal X-ray crystallography provides the most direct, accurate and in most of the cases the only way of forming images of macromolecules. Using crystallography, threedimensional images have been made of thousands of macromolecules, especially proteins and nucleic acids. These give detailed information about their activity, their mechanism for recognizing and binding substrates and effectors, and the conformational changes which they may undergo. This chapter presents the basic crystallographic procedure steps and a thorough survey of the computational software used most frequently by protein X-ray crystallographers. The determination of the structure of 2[4Fe-4S] ferredoxin from Escherichia coli. is examined as a case study of implementation of these steps and programs. Finally, some of the perspectives of the field of computational X-ray crystallography are noted showing the future developments in the ceaseless evolution of new methods and proliferation of new programs.

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