Accommodation of CO in the di-heme active site of cytochrome bd terminal oxidase from Escherichia coli

Borisov, Vitaliy B.; Verkhovsky, Michael I.

doi:10.1016/j.jinorgbio.2012.09.016

Cited by 26 publications

(14 citation statements)

References 36 publications

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“…The conclusion that CO at a high concentration can react with ferrous heme b 558 is consistent with the MCD [35] and CO titration [44] studies. In the slowest recombination phase (24 ms) CO migrates from heme d to heme b 595 in ∼5% of the enzyme population, in agreement with recent work [48]. These data support a model of the cytochrome bd active site in which hemes b 595 and d form the common oxygen reducing pocket but with the negative cooperativity of ligand binding, heme d having a higher affinity.…”

Section: Discussionsupporting

confidence: 88%

“…It is the high-spin pentacoordinate heme [35] ligated by His 19 of subunit I [36] and can mediate electron transfer from heme b 558 to heme d [37]. A number of data suggest that this heme forms a di-heme active site with heme d [3], [35], [38]–[48]. Other authors believe that cytochrome bd does not possess a bimetallic oxygen reductase site [49].…”

Section: Introductionmentioning

confidence: 99%

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Microsecond Time-Resolved Absorption Spectroscopy Used to Study CO Compounds of Cytochrome bd from Escherichia coli

et al. 2014

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Cytochrome bd is a tri-heme (b 558, b 595, d) respiratory oxygen reductase that is found in many bacteria including pathogenic species. It couples the electron transfer from quinol to O2 with generation of an electrochemical proton gradient. We examined photolysis and subsequent recombination of CO with isolated cytochrome bd from Escherichia coli in one-electron reduced (MV) and fully reduced (R) states by microsecond time-resolved absorption spectroscopy at 532-nm excitation. Both Soret and visible band regions were examined. CO photodissociation from MV enzyme possibly causes fast (τ<1.5 µs) electron transfer from heme d to heme b 595 in a small fraction of the protein, not reported earlier. Then the electron migrates to heme b 558 (τ∼16 µs). It returns from the b-hemes to heme d with τ∼180 µs. Unlike cytochrome bd in the R state, in MV enzyme the apparent contribution of absorbance changes associated with CO dissociation from heme d is small, if any. Photodissociation of CO from heme d in MV enzyme is suggested to be accompanied by the binding of an internal ligand (L) at the opposite side of the heme. CO recombines with heme d (τ∼16 µs) yielding a transient hexacoordinate state (CO-Fe2+-L). Then the ligand slowly (τ∼30 ms) dissociates from heme d. Recombination of CO with a reduced heme b in a fraction of the MV sample may also contribute to the 30-ms phase. In R enzyme, CO recombines to heme d (τ∼20 µs), some heme b 558 (τ∼0.2–3 ms), and finally migrates from heme d to heme b 595 (τ∼24 ms) in ∼5% of the enzyme population. Data are consistent with the recent nanosecond study of Rappaport et al. conducted on the membranes at 640-nm excitation but limited to the Soret band. The additional phases were revealed due to differences in excitation and other experimental conditions.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Microsecond Time-Resolved Absorption Spectroscopy Used to Study CO Compounds of Cytochrome bd from Escherichia coli

et al. 2014

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“…Less clear is the function of heme b 595 . Although the X-ray structure of the protein is not available, existing data suggest that heme b 595 could facilitate O 2 reduction at heme d, forming with the latter a di-heme active site [18,20,[26][27][28][29][30][31][32][33][34][35][36][37]. Nevertheless, data inconsistent with the existence of a bimetallic O 2 -reducing site were also reported [13,38].…”

Section: Introductionmentioning

confidence: 99%

Cytochrome bd from Escherichia coli catalyzes peroxynitrite decomposition

Borisov

Forte

Siletsky

et al. 2015

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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Cytochrome bd is a prokaryotic respiratory quinol oxidase phylogenetically unrelated to heme-copper oxidases, that was found to promote virulence in some bacterial pathogens. Cytochrome bd from Escherichia coli was previously reported to contribute not only to proton motive force generation, but also to bacterial resistance to nitric oxide (NO) and hydrogen peroxide (H2O2). Here, we investigated the interaction of the purified enzyme with peroxynitrite (ONOO(-)), another harmful reactive species produced by the host to kill invading microorganisms. We found that addition of ONOO(-) to cytochrome bd in turnover with ascorbate and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) causes the irreversible inhibition of a small (≤15%) protein fraction, due to the NO generated from ONOO(-) and not to ONOO(-) itself. Consistently, addition of ONOO(-) to cells of the E. coli strain GO105/pTK1, expressing cytochrome bd as the only terminal oxidase, caused only a minor (≤5%) irreversible inhibition of O2 consumption, without measurable release of NO. Furthermore, by directly monitoring the kinetics of ONOO(-) decomposition by stopped-flow absorption spectroscopy, it was found that the purified E. coli cytochrome bd in turnover with O2 is able to metabolize ONOO(-) with an apparent turnover rate as high as ~10 mol ONOO(-) (mol enzyme)(-1) s(-1) at 25°C. To the best of our knowledge, this is the first time that the kinetics of ONOO(-) decomposition by a terminal oxidase has been investigated. These results strongly suggest a protective role of cytochrome bd against ONOO(-) damage.

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“…2) and (ii) is insensitive to heme d 2+ binding inhibitors, like NO and CO. This may relate to the recent finding that, following CO equilibration with reduced cytochrome bd, in the enzyme preparation a small population with heme b 595 bound to CO and unliganded heme d can be detected [34]. The finding that cyanide, added to the as-prepared enzyme at a concentration sufficient to fully inhibit its catalase activity, does Fig.…”

Section: Discussionmentioning

confidence: 83%

Cytochrome bd oxidase from Escherichia coli displays high catalase activity: An additional defense against oxidative stress

Borisov¹,

Forte²,

Davletshin³

et al. 2013

FEBS Letters

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Cytochrome bd oxygen reductase from Escherichia coli has three hemes, b558, b595 and d. We found that the enzyme, as-prepared or in turnover with O2, rapidly decomposes H2O2 with formation of approximately half a mole of O2 per mole of H2O2. Such catalase activity vanishes upon cytochrome bd reduction, does not compete with the oxygen-reductase activity, is insensitive to NO, CO, antimycin-A and N-ethylmaleimide (NEM), but is inhibited by cyanide (Ki ~2.5μM) and azide. The activity, possibly associated with heme-b595, was also observed in catalase-deficient E. coli cells following cytochrome bd over-expression suggesting a protective role against oxidative stress in vivo.

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Accommodation of CO in the di-heme active site of cytochrome bd terminal oxidase from Escherichia coli

Cited by 26 publications

References 36 publications

Microsecond Time-Resolved Absorption Spectroscopy Used to Study CO Compounds of Cytochrome bd from Escherichia coli

Microsecond Time-Resolved Absorption Spectroscopy Used to Study CO Compounds of Cytochrome bd from Escherichia coli

Cytochrome bd from Escherichia coli catalyzes peroxynitrite decomposition

Cytochrome bd oxidase from Escherichia coli displays high catalase activity: An additional defense against oxidative stress

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