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175. Dissimilatory Sulfite Reductase

Author

Parey, Kristian, primary, Schiffer, Alexander, additional, Steuber, Julia, additional, Fritz, Günter, additional, Ermler, Ulrich, additional, and Kroneck, Peter MH, additional

Published
2004
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176. Methyl‐Coenzyme M Reductase

Author

Grabarse, Wolfgang, primary, Shima, Seigo, additional, Mahlert, Felix, additional, Duin, Evert C, additional, Thauer, Rudolf K, additional, and Ermler, Ulrich, additional

Published
2004
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181. Living on Sulfate: Three-Dimensional Structure and Spectroscopy of Adenosine 5´-Phosphosulfate Reductase and Dissimilatory Sulfite Reductase.

Author

Dahl, Christiane, Friedrich, Cornelius G., Fritz, Günter, Schiffer, Alexander, Behrens, Anke, Büchert, Thomas, Ermler, Ulrich, and Kroneck, Peter M. H.

Abstract

The reduction of sulfate to sulfide and the reverse reaction are widespread biological processes. Hereby, microorganisms play a central role. Plants also reduce sulfate for the purpose of biosynthesis, and both plants and animals convert reduced sulfur compounds to sulfate. Sulfate respiration is used for energy conservation by strictly anaerobic bacteria and archaea. The redox equivalents generated by the oxidation of organic compounds are transferred to sulfate as the terminal electron acceptor. There are three key enzymes localized in the cytoplasm or at the cytoplasmic aspect of the inner membrane: ATP sulfurylase (ATPS), adenosine 5´-phosphosulfate reductase (APSR), and dissimilatory sulfite reductase (SIR). Sulfate (S6+) cannot be directly reduced by dihydrogen or organic acids, it has to be activated to adenosine 5´-phosphosulfate (APS) catalyzed by ATPS. The enzyme APSR (cofactors flavin adenine dinucleotide, [4Fe4S]) catalyzes the conversion of APS to sulfite (S4+) and AMP, followed by the complex multicomponent enzyme SIR (cofactors siroheme, [4Fe4S]) which catalyzes the reduction of sulfite (S4+) to sulfide (S2?). In this contribution we present the three-dimensional structures of APSR from Archaeoglobus fulgidus and of catalytically relevant reaction intermediates. In addition, we discuss spectroscopic and structural data of SIR purified from this organism. [ABSTRACT FROM AUTHOR]

Published
2007
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192. A decade of crystallization drops: Crystallization of the cbb 3 cytochrome c oxidase from Pseudomonas stutzeri.

Author

Buschmann, Sabine, Richers, Sebastian, Ermler, Ulrich, and Michel, Hartmut

Abstract

The cbb 3 cytochrome c oxidases are distant members of the superfamily of heme copper oxidases. These terminal oxidases couple O2 reduction with proton transport across the plasma membrane and, as a part of the respiratory chain, contribute to the generation of an electrochemical proton gradient. Compared with other structurally characterized members of the heme copper oxidases, the recently determined cbb 3 oxidase structure at 3.2 Å resolution revealed significant differences in the electron supply system, the proton conducting pathways and the coupling of O2 reduction to proton translocation. In this paper, we present a detailed report on the key steps for structure determination. Improvement of the protein quality was achieved by optimization of the number of lipids attached to the protein as well as the separation of two cbb 3 oxidase isoenzymes. The exchange of n-dodecyl-β- d-maltoside for a precisely defined mixture of two α-maltosides and decanoylsucrose as well as the choice of the crystallization method had a most profound impact on crystal quality. This report highlights problems frequently encountered in membrane protein crystallization and offers meaningful approaches to improve crystal quality. [ABSTRACT FROM AUTHOR]

Published
2014
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193. Structure of the (E)-4-hydroxy-3-methyl-but-2-enyl-diphosphate reductase from Plasmodium falciparum.

Author

Rekittke, Ingo, Olkhova, Elena, Wiesner, Jochen, Demmer, Ulrike, Warkentin, Eberhard, Jomaa, Hassan, and Ermler, Ulrich

Subjects
HYDROXY acids, PYROPHOSPHATES, PLASMODIUM falciparum, MALARIA, BINDING sites, ELECTRON donors, REDUCTASES
Abstract

Highlights: [•] LytB of the malaria pathogen Plasmodium falciparum was structurally characterized. [•] The substrate and electron donor binding sites serve as targets for a search for antimalarian drugs. [•] A LytB-[2Fe–2S] ferredoxin complex was modelled by docking calculations. [ABSTRACT FROM AUTHOR]

Published
2013
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194. Advanced electron paramagnetic resonance on the catalytic iron–sulfur cluster bound to the CCG domain of heterodisulfide reductase and succinate: quinone reductase.

Author

Fielding, Alistair J., Parey, Kristian, Ermler, Ulrich, Scheller, Silvan, Jaun, Bernhard, and Bennati, Marina

Subjects
ELECTRON paramagnetic resonance, IRON-sulfur compounds, IRON catalysts, METAL clusters, DISULFIDES, REDUCTASES, SUCCINATES, QUINONE
Abstract

Heterodisulfide reductase (Hdr) is a key enzyme in the energy metabolism of methanogenic archaea. The enzyme catalyzes the reversible reduction of the heterodisulfide (CoM-S-S-CoB) to the thiol coenzymes M (CoM-SH) and B (CoB-SH). Cleavage of CoM-S-S-CoB at an unusual FeS cluster reveals unique substrate chemistry. The cluster is fixed by cysteines of two cysteine-rich CCG domain sequence motifs (CX 31–39CCX 35–36CXXC) of subunit HdrB of the Methanothermobacter marburgensis HdrABC complex. We report on Q-band (34 GHz) 57Fe electron-nuclear double resonance (ENDOR) spectroscopic measurements on the oxidized form of the cluster found in HdrABC and in two other CCG-domain-containing proteins, recombinant HdrB of Hdr from M. marburgensis and recombinant SdhE of succinate: quinone reductase from Sulfolobus solfataricus P2. The spectra at 34 GHz show clearly improved resolution arising from the absence of proton resonances and polarization effects. Systematic spectral simulations of 34 GHz data combined with previous 9 GHz data allowed the unambiguous assignment of four 57Fe hyperfine couplings to the cluster in all three proteins. 13C Mims ENDOR spectra of labelled CoM-SH were consistent with the attachment of the substrate to the cluster in HdrABC, whereas in the other two proteins no substrate is present. 57Fe resonances in all three systems revealed unusually large 57Fe ENDOR hyperfine splitting as compared to known systems. The results infer that the cluster’s unique magnetic properties arise from the CCG binding motif. [ABSTRACT FROM AUTHOR]

Published
2013
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