Cytochrome o (bo) is a proton pump in Paracoccus denitrificans and Escherichia coli

Puustinen, Anne; Finel, Moshe; Virkki, Marika; Wikström, Mårten

doi:10.1016/0014-5793(89)80616-7

Cited by 215 publications

(143 citation statements)

References 22 publications

Supporting

Mentioning

135

Contrasting

Order By: Relevance

“…The titration experiments with the wild-type enzyme were carried out at pH 8. 5. At E h = 0 mV where semiquinone radical was stabilized, we observed a typical ubisemiquinone radical signal at g = 2.0 with partially resolved splittings [14] (Fig.…”

Section: Stabilization Of Ubisemiquinone Radical At Qh Sitementioning

confidence: 77%

Stabilization of a semiquinone radical at the high‐affinity quinone‐binding site (Q_H) of the Escherichia coli bo‐type ubiquinol oxidase

et al. 1995

View full text Add to dashboard Cite

Reaction of ubiquinone in the high-affinity quinonebinding site (QH) in bo-type ubiquinol oxidase from Escherichia coli was revealed by EPR and optical studies. In the Qn site, ubiquinol was shown to be oxidized to ubisemiquinone and to ubiquinone, while no semiquinone signal was detected in the oxidase isolated from mutant cells that cannot synthesize ubiquinone. The Qn site highly stabilized ubisemiquinone radical with a stability constant of 1-4 at pH 8.5 and the stability became lower at the lower pH. Midpoint potential of QH21Q couple was -2 mV at pH 8.5 and showed -60 mVIpH dependence indicative of 2H÷/2e -reaction. The Em was more negative than that of low-spin heme b above pH 7.0. We conclude that the Qn mediates intramolecular electron transfer from ubiquinol in the low-affinity quinol oxidation site (QL) to low-spin heme b. Unique roles of the quinone-binding sites in the bacterial ubiquinoi oxidase are discussed.

show abstract

Section: Stabilization Of Ubisemiquinone Radical At Qh Sitementioning

confidence: 77%

Stabilization of a semiquinone radical at the high‐affinity quinone‐binding site (Q_H) of the Escherichia coli bo‐type ubiquinol oxidase

et al. 1995

View full text Add to dashboard Cite

show abstract

“…A plasmid encoding for the whole R. sphaeroides ccoNOQP operon of cytochrome cbb 3 was introduced in the cells, which expressed no other cytochrome c oxidases, as verified by the sequence of the whole genome of the P. denitrificans 1222 parent strain (SI Materials and Methods), but still retained a proton-pumping quinol oxidase (16). To perform proton-translocation experiments, a KCl-containing solution was placed in the measuring cell and carefully purged with a constant stream of wetted argon to remove excess oxygen, after which the cells were added.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic stoichiometry of proton translocation by cytochrome cbb ₃

Rauhamäki

Bloch²,

Wikström³

2012

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

Self Cite

View full text Add to dashboard Cite

Cytochrome cbb 3 belongs to the superfamily of respiratory hemecopper oxidases that couple the reduction of molecular oxygen to proton translocation across the bacterial or mitochondrial membrane. The cbb 3 -type enzymes are found only in bacteria, and are both structurally and functionally the most distant from their mitochondrial counterparts. The mechanistic H + /e − stoichiometry of proton translocation in these cbb 3 -type cytochrome c oxidases has remained controversial. A stoichiometric efficiency of only one-half that of the mitochondrial aa 3 -type enzyme was recently proposed to be related to adaptation of the organism to microaerobic environments. Here, proton translocation by the Rhodobacter sphaeroides enzyme was studied using purified cytochrome cbb 3 reconstituted into liposomes. An H + /e − stoichiometry of proton translocation close to unity was observed using the oxygen pulse method, but solely in conditions in which the vast majority of the enzyme was fully reduced in the anaerobic state before the O 2 pulse. These data were compared with results using whole cells or spheroplasts, and the discrepancies in the literature data were discussed. Our results suggest that a proton-pumping efficiency of 1 H + /e − may be achieved using the single-proton uptake pathway identified in the structure of cytochrome cbb 3 . The mechanism of proton pumping thus differs from that of the aa 3 -type oxidases of mitochondria and bacteria.cell respiration | proton pumping

show abstract

“…From DNA sequence data, large similarities between subunit I of mammalian cytochrome aa3 and cytochrome bo of E. coli have been demonstrated [20]. In functional terms, both enzymes have been shown to act as redox-driven proton pumps [21,22], but they differ in the naturally used reductant. Cytochrome uu3 generally oxidizes reduced cytochrome c, whereas cytochrome bo functions as an ubiquinol oxidase.…”

Section: Discussionmentioning

confidence: 99%

EPR studies of cytochrome aa₃ from Sulfolobus acidocaldarius

Anemüller

Bill

Schäfer

et al. 1992

European Journal of Biochemistry

View full text Add to dashboard Cite

The purified cytochrome aa3-type oxidase from Suljolobus acidocaldarius (DSM 639) consists of a single subunit, containing one low-spin and one high-spin A-type hemes and copper [Anemiiller, S. and Schafer, G. (1990) Eur. J. Biochem. 191,. The enzyme metal centers were investigated by electron paramagnetic resonance spectroscopy (EPR), coupled to redox potentiometry. The lowspin heme EPR signal has the following g-values: g, = 3.02, g, = 2.23 and g, = 1.45 and the highspin heme exhibits an almost axial spectrum (gy = 6.03 and g, = 5.97, E/D < 0.002). In the enzyme as isolated the low-spin resonance corresponds to 95 10% of the enzyme concentration, while the high-spin signal accounts for only 40 f 5%. However, taking into account the redox potential dependence of the high-spin heme signal, this value also rises to 95 & 10%. The high-spin heme signal of the Suljolobus enzyme shows spectral characteristics distinct from those of the Paracoccus denitrijiicuns one: it shows a smaller rhombicity (8, = 6.1 and g, = 5.9, E/D = 0.004 for the P.

show abstract

Cytochrome o (bo) is a proton pump in Paracoccus denitrificans and Escherichia coli

Cited by 215 publications

References 22 publications

Stabilization of a semiquinone radical at the high‐affinity quinone‐binding site (Q_H) of the Escherichia coli bo‐type ubiquinol oxidase

Stabilization of a semiquinone radical at the high‐affinity quinone‐binding site (Q_H) of the Escherichia coli bo‐type ubiquinol oxidase

Mechanistic stoichiometry of proton translocation by cytochrome cbb ₃

EPR studies of cytochrome aa₃ from Sulfolobus acidocaldarius

Contact Info

Product

Resources

About

Cytochrome o (bo) is a proton pump in Paracoccus denitrificans and Escherichia coli

Cited by 215 publications

References 22 publications

Stabilization of a semiquinone radical at the high‐affinity quinone‐binding site (QH) of the Escherichia coli bo‐type ubiquinol oxidase

Stabilization of a semiquinone radical at the high‐affinity quinone‐binding site (QH) of the Escherichia coli bo‐type ubiquinol oxidase

Mechanistic stoichiometry of proton translocation by cytochrome cbb 3

EPR studies of cytochrome aa3 from Sulfolobus acidocaldarius

Contact Info

Product

Resources

About

Stabilization of a semiquinone radical at the high‐affinity quinone‐binding site (Q_H) of the Escherichia coli bo‐type ubiquinol oxidase

Stabilization of a semiquinone radical at the high‐affinity quinone‐binding site (Q_H) of the Escherichia coli bo‐type ubiquinol oxidase

Mechanistic stoichiometry of proton translocation by cytochrome cbb ₃

EPR studies of cytochrome aa₃ from Sulfolobus acidocaldarius