Any feedback?
Information on EC 7.1.1.7 - quinol oxidase (electrogenic, proton-motive force generating)
for references in articles please use BRENDA:EC7.1.1.7Please wait a moment until all data is loaded. This message will disappear when all data is loaded.
EC Tree
7.1.1.7 quinol oxidase (electrogenic, proton-motive force generating)IUBMB Comments
This terminal oxidase enzyme is unable to pump protons but generates a proton motive force by transmembrane charge separation resulting from utilizing protons and electrons originating from opposite sides of the membrane to generate water. The bioenergetic efficiency (the number of charges driven across the membrane per electron used to reduce oxygen to water) is 1. The bd-I oxidase from the bacterium Escherichia coli is the predominant respiratory oxygen reductase that functions under microaerophilic conditions in that organism. cf. EC 7.1.1.3, ubiquinol oxidase (H+-transporting).
Specify your search results
Word Map
- 7.1.1.7
- oxidases
-
cyddc
-
low-spin
-
photodissociation
-
aa3-type
- menaquinol
- analysis
- medicine
The enzyme appears in viruses and cellular organisms
Reaction Schemes
2
+
+
4
=
2
+
2
+
4
Synonyms
cytochrome bd-i, cytochrome bd quinol oxidase, cydabdc, cytochrome bd-i respiratory oxidase, cytochrome bd-i complex, cytochrome bd-i ubiquinol oxidase, 
more
topPlease wait a moment until the data is sorted. This message will disappear when the data is sorted.
SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
bd-I type oxidase
CydA
CydAB
CydB
CydX
cytochrome bd
cytochrome bd oxidase
cytochrome bd-I respiratory oxidase
cytochrome bd-type quinol oxidase
EC 1.10.3.14
-
-
formerly
-
ubiquinol oxidase (electrogenic, proton-motive force generating)
-
-
-
-
ubiquinol:oxygen oxidoreductase (electrogenic, non H+-transporting)
-
-
-
-
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
2 quinol + O2[side 2] + 4 H+[side 2] = 2 quinone + 2 H2O[side 2] + 4 H+[side 1]
overall reaction
-
-
-
2 quinol = 2 quinone + 4 H+[side 1] + 4 e-
(1a)
-
-
-
O2[side 2] + 4 H+[side 2] + 4 e- = 2 H2O[side 2]
(1b)
-
-
-
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
PATHWAY SOURCE
PATHWAYS
-
, , ,
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
SYSTEMATIC NAME
IUBMB Comments
quinol:oxygen oxidoreductase (electrogenic, non H+-transporting)
This terminal oxidase enzyme is unable to pump protons but generates a proton motive force by transmembrane charge separation resulting from utilizing protons and electrons originating from opposite sides of the membrane to generate water. The bioenergetic efficiency (the number of charges driven across the membrane per electron used to reduce oxygen to water) is 1. The bd-I oxidase from the bacterium Escherichia coli is the predominant respiratory oxygen reductase that functions under microaerophilic conditions in that organism. cf. EC 7.1.1.3, ubiquinol oxidase (H+-transporting).
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
2 1,4-naphthoquinol + O2 + 4 H+[side 1]
2 1,4-naphthoquinone + 2 H2O + 4 H+[side 2]
-
-
-
?
2 2,3-dimethoxy-5-methyl-1,4-benzoquinol + O2 + 4 H+[side 1]
2 2,3-dimethoxy-5-methyl-1,4-benzoquinone + 2 H2O + 4 H+[side 2]
-
-
-
?
2 decylubiquinol + O2[side 2] + 4 H+[side 2]
2 decylubiquinone + 2 H2O[side 2] + 4 H+[side 1]
-
-
-
?
2 duroquinol + O2 + 4 H+[side 1]
2 duroquinone + 2 H2O + 4 H+[side 2]
-
-
-
?
2 menadiol + O2 + 4 H+[side 1]
2 menadione + 2 H2O + 4 H+[side 2]
-
-
-
?
decylubiquinol + H2O2[side 2] + 2 H+[side 2]
decylubiquinone + H2O[side 2] + 2 H+[side 1]
-
-
-
?
2 ubiquinol + O2 + 4 H+[side 1]
2 ubiquinone + 2 H2O + 4 H+[side 2]
-
-
-
-
?
2 ubiquinol + O2 + 4 H+[side 1]
2 ubiquinone + 2 H2O + 4 H+[side 2]
-
respiratory terminal oxidase
-
-
?
menadiol + O2 + H+[side 1]
menadione + H2O + H+[side 2]
-
-
-
-
?
menadiol + O2 + H+[side 1]
menadione + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
additional information
?
-
after the initial binding of O2, the OO bond is heterolytically cleaved to yield a kinetically competent heme d oxoferryl porphyrin pi-cation radical intermediate magnetically interacting with heme b595. This intermediate accumulates to 0.75-0.85 per enzyme in agreement with its much higher rate of formation at 20000 per s compared with its rate of decay of 1900 per s. The intermediate is next converted to a short lived heme d oxoferryl in a phase kinetically matched to the oxidation of heme b558 before completion of the reaction. The results indicate that cytochrome bd oxidases break the O-O bond in a single four-electron transfer without a peroxide intermediate. The fourth electron is donated by the porphyrin moiety rather than by a nearby amino acid
-
-
?
additional information
?
-
enzyme additionally catalyzes oxidation of N,N,N',N'-tetramethyl-p-phenylenediamine. This reaction is sensitive to inhibition by cyanide
-
-
?
additional information
?
-
-
enzyme additionally catalyzes oxidation of N,N,N',N'-tetramethyl-p-phenylenediamine. This reaction is sensitive to inhibition by cyanide
-
-
?
additional information
?
-
-
purified cytochrome bd in turnover with O2 is able to metabolize ONOO- with an apparent turnover rate as high as about 10 mol ONOO- per mol of enzyme and per s at 25°C
-
-
?
additional information
?
-
purified cytochrome bd in turnover with O2 is able to metabolize ONOO- with an apparent turnover rate as high as about 10 mol ONOO- per mol of enzyme and per s at 25°C
-
-
?
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
2 ubiquinol + O2 + 4 H+[side 1]
2 ubiquinone + 2 H2O + 4 H+[side 2]
-
respiratory terminal oxidase
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
-
?
ubiquinol + O2 + H+[side 1]
ubiquinone + H2O + H+[side 2]
-
-
-
?
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
heme
heme b558 and the heme b595/heme d complex are likely to be close to each other. All three hemes are predicted to be near the periplasmic surface
heme
two- to threefold increase in cydAB gene expression upon reduction of the pO2 of the growth medium from 21 to 0.5% air saturation with concomitant increase in d-heme absorbance in spectra of membranes isolated from wild-type Mycobacterium smegmatis cultured at 1% air saturation
heme
the enzyme contains one low-spin haem (b558) and the two high-spin haems (b595 and d) as the redox-active cofactors
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
peroxynitrite
addition of ONOO- to cytochrome bd in turnover with ascorbate and N,N,N',N'-tetramethyl-p-phenylenediamine causes the irreversible inhibition of about 15% of the enzyme fraction, due to the NO radical generated from ONOO-. Addition of ONOO- to cells expressing cytochrome bd as the only terminal oxidase, causes about 5% irreversible inhibition of O2 consumption. Purified cytochrome bd in turnover with O2 is able to metabolize ONOO- with an apparent turnover rate as high as about 10 mol ONOO- per mol of enzyme and per s at 25°C
additional information
enzyme is insensitive to sulfide up to 0.058 mM
-
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
DISEASE
TITLE OF PUBLICATION
LINK TO PUBMED
Infections
The cytochrome bd-I respiratory oxidase augments survival of multidrug-resistant Escherichia coli during infection.
Sepsis
Respiration metabolism of Group B Streptococcus is activated by environmental haem and quinone and contributes to virulence.
Tuberculosis
Characterization of the cydAB-encoded cytochrome bd oxidase from Mycobacterium smegmatis.
Tuberculosis
The carboxy-terminal insert in the Q-loop is needed for functionality of Escherichia coli cytochrome bd-I.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.072
decylubiquinol
pH 7.0, temperature not specified in the publication
6.6
H2O2[side 2]
pH 7.0, temperature not specified in the publication
-
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
101
H2O2[side 2]
pH 7.0, temperature not specified in the publication
-
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
15
H2O2[side 2]
pH 7.0, temperature not specified in the publication
-
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
pH RANGE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
Q927C3 i.e. subunit cydA, Q927C4 i.e. subunit cydB
Q927C3; Q927C4
UniProt
brenda
Q927C3 i.e. subunit cydA, Q927C4 i.e. subunit cydB
Q927C3; Q927C4
UniProt
brenda
B2HQZ0 i.e. subunit cydA, B2HQY9 i.e. subunit cydB
B2HQZ0; B2HQY9
UniProt
brenda
B2HQZ0 i.e. subunit cydA, B2HQY9 i.e. subunit cydB
B2HQZ0; B2HQY9
UniProt
brenda
P0ABJ9 i.e. subunit cydA, P0ABK2 i.e. subunit cydB, P56100 i.e. subunit cydX
UniProt
brenda
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
-
level of the catalytic subunit, CydA, of the bd oxidase is low in spore extracts derived from the wild type, and is upregulated in a mutant lacking the bcc-aa3 supercomplex, EC 7.1.1.5
brenda
-
level of the catalytic subunit, CydA, of the bd oxidase is low in spore extracts derived from the wild type, and is upregulated in a mutant lacking the bcc-aa3 supercomplex, EC 7.1.1.5
-
brenda
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
-
the cytochrome bd-I complexis concentrated in mobile patches in the plasma membrane
brenda
subnit cydA has nine transmembrane helices with the O2 reactive site near the periplasmic surface. Residue His19, the ligand to the high spin heme b595 component of the oxidase, is located near the periplasmic surface of the protein
brenda
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
physiological function
physiological function
inactivation of cydA or cydB by gene disruption results in loss of d-heme absorbance at 631 nm. Inactivation of cydA has no effect on the ability of Mycobacterium smegmatis to exit from stationary phase at 37 or 42°C. No discernible growth defect of the mutant is observed under moderately aerobic conditions, while the mutant displays a significant growth disadvantage when cocultured with the wild type under extreme microaerophilia. The cydA mutant displays a competitive growth disadvantage in the presence of the terminal oxidase inhibitor, cyanide, when cocultured with wild type at 21% air saturation in an oxystat
physiological function
inactivation of cydA or cydB gene disruption results in loss of d-heme absorbance at 631 nm
physiological function
-
induction of cytochrome bd helps Salmonella grow and respire in the presence of inhibitory nitric oxide
physiological function
the enzyme contributes to bacterial resistance to nitric oxide and hydrogen peroxide
physiological function
the enzyme contributes to Escherichia coli survival in the mouse bladder
physiological function
-
the enzyme is important for survival of Mycobacterium smegmatis under peroxide and antibiotic-induced stress
physiological function
-
the expression of cytochrome bd enhances bacterial tolerance to nitrosative stress
physiological function
besides its oxidase activity, cytochrome bd is a genuine quinol peroxidase that reduces hydrogen peroxide to water. The enzyme does not display catalase activity
physiological function
Q927C3; Q927C4
both cytochrome bd-type CydAB, EDC 7.1.1.7, and cytochrome aa3-type menaquinol QoxAB oxidase, EC 7.1.1.5, are used for respiration under different oxygen tensions. Possession of both terminal oxidases is important in infection. In air, the CydAB bd-type oxidase is essential for aerobic respiration and intracellular replication, and cydAB mutants are highly attenuated in mice. At 1% O2 (vol/vol), both oxidases are functional, and the presence of either is sufficient for aerobic respiration and intracellular replication. At 0.2% O2 (vol/vol), both oxidases are necessary for maximum growth
physiological function
in respiratory mutants, both O2-consumption and aerobic growth are unaffected by up to 200 microM sulfide when cytochrome bd-I or bd-II enzyme actes as the only terminal oxidase. Wild-type Escherichia coli shows sulfide-insensitive respiration and growth under conditions favouring the expression of bd oxidases
physiological function
loss of the flavohemoglobin Hmp and cytochrome bd-I elicit high sensitivity to NO-mediated growth inhibition. The subunits cydAB mutant displays an attenuated colonisation phenotype in a mouse model after 2 days
physiological function
-
the bd oxidase functions in controlling electron flux. A mutant lacking the cytochrome bd oxidase shows developmental defects during growth on buffered rich medium plates with glucose as the energy substrate. Cytochrome bd oxidase is essential for the bacterium to grow and complete its developmental cycle under oxygen limitation
physiological function
the interheme electron backflow reaction induced by photodissociation of CO from heme d in one-electron reduced cytochrome bd-I comprises two kinetically different phases: the fast electron transfer from heme d to heme b595 within 0.2-1.5 micros and the slower electron equilibration with tau of about 16 micros. At 200 ns, there is no electron transfer
physiological function
the unresolved photodissociation of CO is followed by a four-phased recombination with characteristic times of about 20 micros, 250 micros, 1.1 ms, and 24 ms. The 20x02micros phase most likely reflects bimolecular recombination of CO with heme d. The 250x02micros phase is heterogeneous and includes recombination of CO with about 7% of heme b595 and transition of heme d from a pentacoordinate to a transient hexacoordinate state in this enzyme population. The 24x02ms transition probably reflects a return of heme d to the pentacoordinate state in the same protein fraction. The 1.1x02ms phase reflects a recombination of CO with about 15% of heme b558
physiological function
when cystine is provided and sulfide levels rise, Escherichia coli becomes strictly dependent upon cytochrome bd oxidase for continued respiration. Low-micromolar levels of sulfide inhibit the proton-pumping cytochrome bo oxidase. In the absence of the back-up cytochrome bd oxidase, growth fails. Exogenous sulfide elicits the same effect
physiological function
-
the bd oxidase functions in controlling electron flux. A mutant lacking the cytochrome bd oxidase shows developmental defects during growth on buffered rich medium plates with glucose as the energy substrate. Cytochrome bd oxidase is essential for the bacterium to grow and complete its developmental cycle under oxygen limitation
-
physiological function
-
both cytochrome bd-type CydAB, EDC 7.1.1.7, and cytochrome aa3-type menaquinol QoxAB oxidase, EC 7.1.1.5, are used for respiration under different oxygen tensions. Possession of both terminal oxidases is important in infection. In air, the CydAB bd-type oxidase is essential for aerobic respiration and intracellular replication, and cydAB mutants are highly attenuated in mice. At 1% O2 (vol/vol), both oxidases are functional, and the presence of either is sufficient for aerobic respiration and intracellular replication. At 0.2% O2 (vol/vol), both oxidases are necessary for maximum growth
-
physiological function
-
the enzyme is important for survival of Mycobacterium smegmatis under peroxide and antibiotic-induced stress
-
physiological function
-
the enzyme contributes to Escherichia coli survival in the mouse bladder
-
Show AA Sequence and Transmembrane Helices (332 entries)
Please use the AA Sequence and Transmembrane Helices Search for a specific query.
Please use the AA Sequence and Transmembrane Helices Search for a specific query.
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
PDB
SCOP
CATH
UNIPROT
ORGANISM
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
additional information
-
the purified, enzymatically active cytochrome d complex solubilized in Triton X-100 is an alphabeta heterodimer
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
D239A
mutation in subunit cydA. Mutant is not able to confer the ability to grow aerobically to a strain that has no genomically encoded respiratory oxidases. Heme content similar to wild-type, complete loss of ubiquinol oxidase activity
D239N
mutation in subunit cydA. Mutant is not able to confer the ability to grow aerobically to a strain that has no genomically encoded respiratory oxidases. Heme content similar to wild-type, complete loss of ubiquinol oxidase activity
D29E
mutation in subunit cydB. Mutant is totally inactive, and hemes d and b595 are not present in the isolated enzyme
E107D
mutation in subunit cydA. About 15% of the heme contant of wild-type, complete loss of ubiquinol oxidase activity
E107Q
mutation in transmembrane helix III of subunit cydA. Mutant is totally inactive, but retains its hemes. Residue E107 is protonated at pH 7.6 and is perturbed by the reduction of the heme d/heme b595 binuclear center at the active site
E257A
mutation of an acidic residue of subunit cydA at or near the quinol-binding site, mutation inactivates the enzyme but has no substantial influence on the Fourier transform infrared redox difference spectrum
E99A
mutation in subunit cydA. Mutant is not able to confer the ability to grow aerobically to a strain that has no genomically encoded respiratory oxidases. Complete loss of heme d and heme b595 and of ubiquinol oxidase activity
E99Q
mutation in subunit cydA. Mutant is not able to confer the ability to grow aerobically to a strain that has no genomically encoded respiratory oxidases. Complete loss of heme d and heme b595 and of ubiquinol oxidase activity
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
EXPRESSION
ORGANISM