The chromone inhibitor stigmatellin ‐ binding to the ubiquinol oxidation center at the C‐side of the mitochondrial membrane

Jagow, Gebhard von; Ohnishi, Tomo̧ko

doi:10.1016/0014-5793(85)80929-7

Cited by 172 publications

(124 citation statements)

References 18 publications

Supporting

Mentioning

108

Contrasting

Order By: Relevance

“…Both compounds have been shown to be effective inhibitors of quinol-plastocyanin oxidoreductase activity [4,5], and in this study, they both produce a line narrowing of the Rieske center EPR signal and alter the binding of DBMIB to this center. In contrast to the results with the mitochondrial cytochrome b-c complex, stigmatellin does not change the Em of the Rieske center, nor does it cause a red shift in the spectrum of cytochrome b-563 [3]. DNP-INT shows similar properties in all respects.…”

Section: Discussioncontrasting

confidence: 97%

“…Inhibitors which bind in the vicinity of the Rieske center based on changes in the center's EPR spectrum have also been found to alter the midpoint redox potential of the center [3,8,10,11]. As shown in fig.2, the Rieske center of the cytochrome b6-f titrates with an E,,, = 295 mV, and neither stigmatellin nor DNP-INT has signifi- fig.3B and C, the addition of either inhibitor after the addition of DBMIB causes a reappearance of the g= 1.94 signal.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Interaction of stigmatellin and DNP‐INT with the Rieske iron‐sulfur center of the chloroplast cytochrome b₆‐f complex

Malkin¹

1986

FEBS Letters

View full text Add to dashboard Cite

Stigmatellin and DNP‐INT are effective inhibitors of the catalytic activity of the plastoquinol‐plastocyanin oxidoreductase complex (cytochrome b6‐f complex). Both inhibitors alter the EPR spectrum of the Rieske iron‐sulfur center but do not produce band‐shifts of cytochrome b‐563. The midpoint redox potential of the Rieske center is unaffected by either inhibitor, although both alter the DBMIB‐induced g‐value shifts of the Rieske center. The results are considered in terms of binding domains for inhibitors in the cytochrome b6‐f complex.

show abstract

Section: Discussioncontrasting

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Interaction of stigmatellin and DNP‐INT with the Rieske iron‐sulfur center of the chloroplast cytochrome b₆‐f complex

Malkin¹

1986

FEBS Letters

View full text Add to dashboard Cite

show abstract

“…As in the case of (see below). It has been reported by Ohnishi, von Jagow, and co-workers (23,24) that stigmatellin raises the E m of ISP in cytochrome reductase preparations by 250 mV. Because in our reverse electron transfer experiments, the extent of b reduction was much greater in the presence than in the absence of stigmatellin, we were concerned that stigmatellin may be promoting b reduction by a mechanism not involving ISP and an antimycin-sensitive pathway.…”

Section: Resultsmentioning

confidence: 76%

Ubiquinol:Cytochrome c Oxidoreductase

Matsuno‐Yagi

Hatefi

1999

Journal of Biological Chemistry

View full text Add to dashboard Cite

The effects of inhibitors on the reduction of the bisheme cytochrome b of ubiquinol: cytochrome c oxidoreductase (complex III, bc 1 complex) has been studied in bovine heart submitochondrial particles (SMP) when cytochrome b was reduced by NADH and succinate via the ubiquinone (Q) pool or by ascorbate plus N,N,N,Ntetramethyl-p-phenylenediamine via cytochrome c 1 and the iron-sulfur protein of complex III (ISP). The inhibitors used were antimycin (an N-side inhibitor), ␤-methoxyacrylate derivatives, stigmatellin (P-side inhibitors), and ethoxyformic anhydride, which modifies essential histidyl residues in ISP. In agreement with our previous findings, the following results were obtained: (i) When ISP/cytochrome c 1 were prereduced or SMP were treated with a P-side inhibitor, the high potential heme b H was fully and rapidly reduced by NADH or succinate, whereas the low potential heme b L was only partially reduced. with an EPR signal centered at g ϭ 1.90, and a cytochrome c 1 (E m ϭ ϩ 230 mV) (1, 7). In the mitochondrial respiratory chain, complex III transfers electrons from the ubiquinone pool to cytochrome c in a reaction that is coupled to outward proton translocation with a stoichiometry of H ϩ /e ϭ 2. When properly isolated, purified bovine heart complex III catalyzes the reduction of cytochrome c by ubiquinol-2 at a rate of 2500 -3000 s Ϫ1 at 38°C (8, 9).Recently, x-ray crystallographic data have been published at 2.9 Å resolution by Yu and co-workers (2, 10 -12) for about 80% of the bovine enzyme, at 3.0 Å resolution by Zhang et al. We have shown recently in energized submitochondrial particles (SMP) that reverse electron transfer from ISP/c 1 to cytochrome b is inhibited more by antimycin, which binds near b H , than by myxothiazol, which binds near b L (13). Antimycin also inhibited reverse electron transfer from ISP/c 1 to b in Q-extracted SMP, which contained Յ0.06 mol Q/mol cytochrome b or c 1 (200-fold less than the unextracted SMP) and was incapable of oxidizing NADH or succinate by molecular oxygen (13). We have also shown that when SMP were treated with antimycin, KCN, and ascorbate plus TMPD to reduce the high potential centers of complex III, subsequent addition of NADH or succinate resulted in rapid and complete reduction of b H , and only the reduction of b L became slow and partial when ISP/c 1 were prereduced (14). These and other results reported in Refs. 13 and 14 are not compatible with the Q cycle hypothesis, but they are fully consistent with the x-ray diffraction data of the three different groups mentioned, especially because these

show abstract

“…To verify that the observed center indeed arises from the Rieske cluster of the cyt bc 1 complex, we titrated the sample in the presence of the Q O -site inhibitor stigmatellin that increases the E m of the Rieske cluster specifically in this complex (22). Presence of 20 M stigmatellin resulted in the appearance of 2 separate waves, one with the E m of the uninhibited center and a second one with an E m increased by almost 100 mV (Fig.…”

Section: Resultsmentioning

confidence: 96%

Menaquinone as pool quinone in a purple bacterium

Schoepp‐Cothenet

Lieutaud

Baymann

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

112

107

View full text Add to dashboard Cite

Purple bacteria have thus far been considered to operate lightdriven cyclic electron transfer chains containing ubiquinone (UQ) as liposoluble electron and proton carrier. We show that in the purple ␥-proteobacterium Halorhodospira halophila, menaquinone-8 (MK-8) is the dominant quinone component and that it operates in the QB-site of the photosynthetic reaction center (RC). The redox potentials of the photooxidized pigment in the RC and of the Rieske center of the bc1 complex are significantly lower (Em ‫؍‬ ؉270 mV and ؉110 mV, respectively) than those determined in other purple bacteria but resemble those determined for species containing MK as pool quinone. These results demonstrate that the photosynthetic cycle in H. halophila is based on MK and not on UQ. This finding together with the unusual organization of genes coding for the bc1 complex in H. halophila suggests a specific scenario for the evolutionary transition of bioenergetic chains from the low-potential menaquinones to higher-potential UQ in the proteobacterial phylum, most probably induced by rising levels of dioxygen 2.5 billion years ago. This transition appears to necessarily proceed through bioenergetic ambivalence of the respective organisms, that is, to work both on MK-and on UQ-pools. The establishment of the corresponding low-and high-potential chains was accompanied by duplication and redox optimization of the bc1 complex or at least of its crucial subunit oxidizing quinols from the pool, the Rieske protein. Evolutionary driving forces rationalizing the empirically observed redox tuning of the chain to the quinone pool are discussed.electron transport ͉ evolution ͉ photosynthesis C hemiosmotic energy-converting mechanisms in all life on this planet are variations on a strikingly conserved theme. Electrons derived from reduced substrates enter a chain of membrane-integral and/or associated enzymes and are channeled on toward terminal electron-accepting substrates. Some of the free energy available during individual electron-transfer steps is stored in a transmembrane proton motive gradient. Mitchell (1) proposed a general mechanism for coupling electron transfer to proton translocation, which accounts for the majority of these systems. In this mechanism, electrons travel through 2 types of carrier ''arms'' back and forth across the energetic membrane. In an ''electrogenic arm,'' electrons move alone across the membrane from the positively to the negatively charged side, building up an electric field. Via a ''neutral arm,'' electrons travel in the opposite direction, along with protons. Placing electrogenic and neutral arms in series leads to net proton translocation across the membrane.Without exception, the chemiosmotic neutral arms involve diffusion of small, lipophilic molecules across the energetic membrane. In all bioenergetic systems except methanogenesis, these molecules are quinones that diffuse in the lipid bilayer. The bulk of these diffusing quinones electrochemically connecting redox enzymes is called the quinone pool, to disti...

show abstract

The chromone inhibitor stigmatellin ‐ binding to the ubiquinol oxidation center at the C‐side of the mitochondrial membrane

Abstract: Cytochrome bc2 complex Inhibitor Fe2S2 protein EPR Cytochrome b Stigmatellin

Cited by 172 publications

References 18 publications

Interaction of stigmatellin and DNP‐INT with the Rieske iron‐sulfur center of the chloroplast cytochrome b₆‐f complex

Interaction of stigmatellin and DNP‐INT with the Rieske iron‐sulfur center of the chloroplast cytochrome b₆‐f complex

Ubiquinol:Cytochrome c Oxidoreductase

Menaquinone as pool quinone in a purple bacterium

Contact Info

Product

Resources

About

The chromone inhibitor stigmatellin ‐ binding to the ubiquinol oxidation center at the C‐side of the mitochondrial membrane

Abstract: Cytochrome bc2 complex Inhibitor Fe2S2 protein EPR Cytochrome b Stigmatellin

Cited by 172 publications

References 18 publications

Interaction of stigmatellin and DNP‐INT with the Rieske iron‐sulfur center of the chloroplast cytochrome b6‐f complex

Interaction of stigmatellin and DNP‐INT with the Rieske iron‐sulfur center of the chloroplast cytochrome b6‐f complex

Ubiquinol:Cytochrome c Oxidoreductase

Menaquinone as pool quinone in a purple bacterium

Contact Info

Product

Resources

About

Interaction of stigmatellin and DNP‐INT with the Rieske iron‐sulfur center of the chloroplast cytochrome b₆‐f complex

Interaction of stigmatellin and DNP‐INT with the Rieske iron‐sulfur center of the chloroplast cytochrome b₆‐f complex