The [2Fe-2S] centre of the cytochrome bc complex in Bacillus firmus OF4 in EPR: an example of a menaquinol-oxidizing Rieske centre

Riedel, A.; Kellner, Eva; Grodzitzki, Dirk; Liebl, Ursula; Hauska, Günter; Müller, Adolf; Rutherford, A. William; Nitschke, Wolfgang

doi:10.1016/0005-2728(93)90227-7

Cited by 22 publications

(14 citation statements)

References 27 publications

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“…The presence of these two hydrogen bonds in the wild-type protein would decrease the electron density in the cluster and facilitate delocalization of the electron in the cluster during reduction of Fe-2. The potential of the iron-sulfur protein with the S183A mutation is comparable to that observed in menaquinol oxidizing bc complexes (27), where alanine instead of serine has been found in the native sequences (28).…”

Section: Discussionsupporting

confidence: 51%

Alteration of the Midpoint Potential and Catalytic Activity of the Rieske Iron-Sulfur Protein by Changes of Amino Acids Forming Hydrogen Bonds to the Iron-Sulfur Cluster

Denke

Merbitz-Zahradnik

Hatzfeld

et al. 1998

Journal of Biological Chemistry

170

150

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The crystal structure of the bovine Rieske iron-sulfur protein indicates a sulfur atom (S-1) of the iron-sulfur cluster and the sulfur atom (S ␥ ) of a cysteine residue that coordinates one of the iron atoms form hydrogen bonds with the hydroxyl groups of Ser-163 and Tyr-165, respectively. We have altered the equivalent Ser-183 and Tyr-185 in the Saccharomyces cerevisiae Rieske ironsulfur protein by site-directed mutagenesis of the ironsulfur protein gene to examine how these hydrogen bonds affect the midpoint potential of the iron-sulfur cluster and how changes in the midpoint potential affect the activity of the enzyme.Eliminating the hydrogen bond from the hydroxyl group of Ser-183 to S-1 of the cluster lowers the midpoint potential of the cluster by 130 mV, and eliminating the hydrogen bond from the hydroxyl group of Tyr-185 to S ␥ of Cys-159 lowers the midpoint potential by 65 mV. Eliminating both hydrogen bonds has an approximately additive effect, lowering the midpoint potential by 180 mV. Thus, these hydrogen bonds contribute significantly to the positive midpoint potential of the cluster but are not essential for its assembly. The activity of the bc 1 complex decreases with the decrease in midpoint potential, confirming that oxidation of ubiquinol by the iron-sulfur protein is the rate-limiting partial reaction in the bc 1 complex, and that the rate of this reaction is extensively influenced by the midpoint potential of the iron-sulfur cluster.The Rieske iron-sulfur protein is a ubiquitous component of cytochrome bc 1 complexes (1-4) and has been shown to be essential for electron transfer and energy transduction by purification of the protein in a reconstitutively active form and reconstitution to iron-sulfur protein depleted bc 1 complex (5, 6). The electronic environment of the [2Fe-2S] cluster in the Rieske iron-sulfur protein differs from that in plant type [2Fe-2S] ferredoxins as evidenced by a distinct EPR spectrum (1) and a redox midpoint potential of the Rieske protein (e.g. ϩ280 mV) that is much more positive than the midpoint potentials typical of the ferredoxins (e.g. Ϫ420 mV; Ref. 2). The high midpoint potential of the iron-sulfur cluster is essential for the function of the Rieske protein in the Q cycle mechanism of the bc 1 complex (7,8), in which the Rieske protein is the primary electron acceptor and drives the electron transfer reaction by oxidizing ubiquinol and divergently transferring one electron to cytochrome c 1 , while the ubisemiquinone that is formed from ubiquinol reduces the low potential b heme.Recently, the crystal structure of the water-soluble part of the Rieske iron-sulfur protein of bovine heart mitochondrial bc 1 complex has been elucidated at 1.5 Å (9, 10). Ten ␤ strands form three layers of anti-parallel ␤ sheets in a flat spherical molecule as shown in Fig. 1A. The cluster binding fold is a small domain-like structure comprising approximately 46 residues; it consists of a distorted four-stranded antiparallel ␤-sheet and three loops. The loops between the strands ␤4...

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Section: Discussionsupporting

confidence: 51%

Alteration of the Midpoint Potential and Catalytic Activity of the Rieske Iron-Sulfur Protein by Changes of Amino Acids Forming Hydrogen Bonds to the Iron-Sulfur Cluster

Denke

Merbitz-Zahradnik

Hatzfeld

et al. 1998

Journal of Biological Chemistry

170

150

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“…Redox Midpoint Potentials-g av ϭ 1.91 2Fe2S clusters were found with redox midpoint potentials at (a) ϩ400 mV in plasma membranes of the archaeon Sulfolobus acidocaldarius (Anemü ller et al, 1993(Anemü ller et al, , 1994, (b) at around ϩ300 mV in cytochrome bc 1 and b 6 f complexes with ubiquinonol and plastoquinol as electron donors to the complex (Ding et al, 1992;Nitschke et al, 1992), (c) at around ϩ130 mV in the menaquinol-oxidizing cytochrome bc complexes Riedel et al 1993), and (d) at around Ϫ100 mV in bacterial oxygenases (Mason and Cammack, 1992;Rosche et al, 1995b). The class of these 2Fe2S centers thus covers a range of more than 500 mV.…”

Section: The G Av ϭ 191 2fe2s Centers From Bacterial Oxygenases and mentioning

confidence: 99%

“…constant E m below pH 8 and decreasing E m with a slope Ͼ Ϫ60 mV per pH unit above pH 8.0 (Prince and Dutton, 1976;Riedel et al, 1993). In these centers, the involvement of two deprotonatable groups having distinct pK values has been proposed Nitschke et al, 1992;Link et al, 1992;Link, 1994).…”

Section: The G Av ϭ 191 2fe2s Centers From Bacterial Oxygenases and mentioning

confidence: 99%

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EPR, Electron Spin Echo Envelope Modulation, and Electron Nuclear Double Resonance Studies of the 2Fe2S Centers of the 2-Halobenzoate 1,2-Dioxygenase from Burkholderia (Pseudomonas) cepacia 2CBS

Riedel

Fetzner

Rampp

et al. 1995

Journal of Biological Chemistry

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The 2-halobenzoate 1,2-dioxygenase from Burkholderia (Pseudomonas) cepacia 2CBS (Fetzner, S., Mü ller, R., and Lingens, F. (1992) J. Bacteriol. 174, 279 -290) contains both a ferredoxin-type and a Rieske-type 2Fe2S center. These two significantly different 2Fe2S clusters were characterized with respect to their EPR spectra, electrochemical properties (Rieske-type cluster with g z ‫؍‬ 2.025, g y ‫؍‬ 1.91, g x ‫؍‬ 1.79, g av ‫؍‬ 1.91, E m ‫؍‬ ؊125 ؎ 10 mV; ferredoxin-type center with g z ‫؍‬ 2.05, g y ‫؍‬ 1.96, g x ‫؍‬ 1.89, g av ‫؍‬ 1.97, E m ‫؍‬ ؊200 ؎ 10 mV) and pH dependence thereof. X band electron spin echo envelope modulation and electron nuclear double resonance spectroscopy was applied to study the interaction of the Rieske-type center of the 2-halobenzoate 1,2-dioxygenase with 2Fe2S clusters are usually divided into two distinct groups on the basis of their EPR spectra. The ferredoxin-type 2Fe2S centers are characterized by an average g-value of g av ϭ 1.96, whereas the so-called Rieske-type 2Fe2S centers show a pronounced g-factor anisotropy with g av ϭ 1.91.For a long time, the membership in either of the two classes was considered to be correlated with significantly different redox midpoint potentials, i.e. with an E m 1 Ͻ Ϫ400 mV for the ferredoxins and an E m Ͼ ϩ260 mV for the Rieske centers of the cytochrome bc complexes, the enzymes in which such a 2Fe2S center had been discovered (Rieske et al., 1964). The midpoint potential of the Rieske centers was supposed to arise from a different coordination of the cluster compared to ferredoxintype centers.To date, crystal structures of six 2Fe2S ferredoxins are available (Tsukihara et al., 1981;Tsutsui et al., 1983;Rypniewski et al., 1991;Sussman et al., 1989;Correll et al., 1992;Jacobson et al., 1993) showing that the iron atoms are coordinated by four cysteines and are bridged by a pair of acid-labile sulfur atoms. For the Rieske centers, no x-ray structure has been solved yet. The model of the cluster suggesting a coordination via two cysteines and two histidines is supported by 15 N Q band EN-DOR experiments on the terminal oxygenase of the phthalate dioxygenase from Pseudomonas cepacia (Gurbiel et al., 1989). Resonances in the frequency range below 10 MHz were attributed to two slightly inequivalent nitrogen nuclei from histidines interacting with one of the iron ions. The hyperfine coupling constants were claimed to be too high for only dipolar interaction postulating a covalent binding between the iron atom and the histidines. Further ENDOR, ESEEM, and extended x-ray absorption fine structure studies as well as results obtained from site-specific mutagenesis were interpreted in favor of this model (Gurbiel et al., 1991;Britt et al., 1991;Shergill and Cammack, 1994a;Powers et al., 1989;Tsang et al., 1989;Davidson et al., 1992).During recent years, the discovery of several "odd" systems weakened the clearcut E m distinction between the g av ϭ 1.91 and g av ϭ 1.96 clusters. (a) 2Fe2S clusters contained in cytochrome bc complexes involved in oxidation ...

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“…Both groups show biophysical and structural similarities, like the presence of histidyl ligands and significant higher reduction potentials compared to other proteins containing [2Fe-2S] clusters. The soluble proteins exhibit pHindependent reduction potentials ranging from -150 to +5 mV [10,11], whereas the potentials of the proteins found in respiratory chains are pH dependent and typically vary from +105 to +350 mV [12,13]. The latter have been exclusively found as components of the bcl/b6f complexes together with b-and ctype cytochromes [7,8].…”

Section: Introductionmentioning

confidence: 99%

Purification and characterization of the Rieske iron‐sulfur protein from the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius

et al. 1995

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The [2Fe-2S] centre of the cytochrome bc complex in Bacillus firmus OF4 in EPR: an example of a menaquinol-oxidizing Rieske centre

Cited by 22 publications

References 27 publications

Alteration of the Midpoint Potential and Catalytic Activity of the Rieske Iron-Sulfur Protein by Changes of Amino Acids Forming Hydrogen Bonds to the Iron-Sulfur Cluster

Alteration of the Midpoint Potential and Catalytic Activity of the Rieske Iron-Sulfur Protein by Changes of Amino Acids Forming Hydrogen Bonds to the Iron-Sulfur Cluster

EPR, Electron Spin Echo Envelope Modulation, and Electron Nuclear Double Resonance Studies of the 2Fe2S Centers of the 2-Halobenzoate 1,2-Dioxygenase from Burkholderia (Pseudomonas) cepacia 2CBS

Purification and characterization of the Rieske iron‐sulfur protein from the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius

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