An alternative cytochrome oxidase of Paracoccus denitrificans functions as a proton pump

Raitio, Mirja; Wikström, Mårten

doi:10.1016/0005-2728(94)90140-6

Cited by 57 publications

(49 citation statements)

References 33 publications

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“…1B). A stoichiometry very close to 3 H + /e − was obtained (Table 1) in agreement with the data reported previously (7,9,10). On blocking the cytochrome bc 1 complex with myxothiazol ( Fig.…”

Section: Resultssupporting

confidence: 91%

“…1A), the measured H + /e − ratio decreased to 2 ( Fig. 1B and Table 1), as expected from the known H + /e − stoichiometry of the quinol oxidase (16) and as found earlier (7,10). The P. denitrificans AO1 cells with no added plasmid showed a stoichiometry of 2 H + /e − , independent of the addition of myxothiazol.…”

Section: Resultssupporting

confidence: 85%

“…The proton translocation stoichiometry of the cbb 3 -type oxidase was originally reported to be close to 1 H + /e − in Paracoccus denitrificans spheroplasts, when assayed during oxidation of succinate (7). Although this finding was challenged at first (8), the observation of proton pumping by cytochrome cbb 3 in a strain where both the aa 3 -type cytochrome c oxidase and the quinol oxidase had been removed by mutagenesis (9) was subsequently confirmed.…”

mentioning

confidence: 88%

“…Although this finding was challenged at first (8), the observation of proton pumping by cytochrome cbb 3 in a strain where both the aa 3 -type cytochrome c oxidase and the quinol oxidase had been removed by mutagenesis (9) was subsequently confirmed. In contrast, with N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) plus ascorbate as the electron donor system, the apparent stoichiometry was reported to be lower (7,9). Later, Toledo-Cuevas et al (10) studied Rhodobacter sphaeroides cells and reported a stoichiometry close to 1 H + /e − for cytochrome cbb 3 both during oxidation of succinate and TMPD plus ascorbate, and Tsukita et al (11) found 0.75 H + /e − with TMPD plus ascorbate for cytochrome cbb 3 in Helicobacter pylori cells.…”

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confidence: 99%

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Mechanistic stoichiometry of proton translocation by cytochrome cbb ₃

Rauhamäki

Bloch²,

Wikström³

2012

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

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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

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 85%

mentioning

confidence: 88%

mentioning

confidence: 99%

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Mechanistic stoichiometry of proton translocation by cytochrome cbb ₃

Rauhamäki

Bloch²,

Wikström³

2012

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

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“…Despite lacking the D pathway responsible for conducting the pumped protons in the A-type oxidases, the C and B oxidases have been shown to pump protons (1,18,(32)(33)(34)(35) but with a lower stoichiometry than in A-type HCuOs (1, 18, 35, but see refs. 32 and 34 where n ¼ 4 was obtained on the whole cell level), suggesting that there is a link between using only one pathway and pumping fewer protons (1).…”

Section: Discussionmentioning

confidence: 99%

Entrance of the proton pathway in cbb ₃ -type heme-copper oxidases

Lee

Gennis²,

Ädelroth

2011

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

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Heme-copper oxidases (HCuOs) are the last components of the respiratory chain in mitochondria and many bacteria. They catalyze O 2 reduction and couple it to the maintenance of a proton-motive force across the membrane in which they are embedded. In the mitochondrial-like, A family of HCuOs, there are two well established proton transfer pathways leading from the cytosol to the active site, the D and the K pathways. In the C family (cbb 3 ) HCuOs, recent work indicated the use of only one pathway, analogous to the K pathway. In this work, we have studied the functional importance of the suggested entry point of this pathway, the Glu-25 (Rhodobacter sphaeroides cbb 3 numbering) in the accessory subunit CcoP (E25 P ). We show that catalytic turnover is severely slowed in variants lacking the protonatable Glu-25. Furthermore, proton uptake from solution during oxidation of the fully reduced cbb 3 by O 2 is specifically and severely impaired when Glu-25 was exchanged for Ala or Gln, with rate constants 100-500 times slower than in wild type. Thus, our results support the role of E25 P as the entry point to the proton pathway in cbb 3 and that this pathway is the main proton pathway. This is in contrast to the A-type HCuOs, where the D (and not the K) pathway is used during O 2 reduction. The cbb 3 is in addition to O 2 reduction capable of NO reduction, an activity that was largely retained in the E25 P variants, consistent with a scenario where NO reduction in cbb 3 uses protons from the periplasmic side of the membrane.glutamate | nitric oxide | oxygen reduction

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