| TCID | Name | Domain | Kingdom/Phylum | Protein(s) |
|---|---|---|---|---|
|
3.D.4.1.1 | Quinol oxidase, SoxABC (Lubben et al., 1992) | Archaea |
Thermoproteota | SoxABC of Sulfolobus acidocaldarius SoxA (168 aas; P39479) SoxB (517 aas; P98004) SoxC (563 aas; P39480) |
|
3.D.4.1.2 | The cytochrome ba complex consisting of the Sox/CbsA/cytb protein of 553 aas and 12 TMSs, and the CbsB or cytochrome b573 protein of 311 aas and 9 TMSs (Bandeiras et al. 2009). May function with SoxL (Q3LCJ1; 329 aas and 2 TMSs) and CbsB (Q3LCJ3; 311 aas and 2 TMSs). | Archaea |
Thermoproteota | Cytba of Acidianus ambivalens (Desulfurolobus ambivalens) |
|
3.D.4.2.1 | Cytochrome ba3 oxidase, CbaABC or CcO. The 3-d structure is known (PDB# 1EHK) (Lee et al., 2012). Proton transfer has been reviewed (von Ballmoos et al., 2012). A mutation in subunit A, D372I, a probable pump H+ binding site, uncouples H+ transport from electron flow (von Ballmoos et al. 2015). In this cytochrome ba3, O2 molecules that arrive at the reduction site diffuse through the X-ray-observed tunnel, supporting its role as the main O2 delivery pathway in this cytochrome ba3 as well as the cytokchrome aa3 of Rhodobacter spheroides (Mahinthichaichan et al. 2018). The proton loading site cluster in the ba3 cytochrome c oxidase that loads and traps protons has been identified (Cai et al. 2020). | Bacteria |
Deinococcota | CbaABC of Thermus thermophilus CbaA (Q56408) CbaB (P98052) CbaC (P82543) |
|
3.D.4.2.2 | Nitrous oxide reductase, NosZ, of 652 aas with one N-terminal TMS. The NosZ enzyme is the terminal reductase of anaerobic N2O
respiration. Electrons derived from a donor substrate are
transferred to NosZ by means of an electron transport chain (ETC) that
conserves energy through proton motive force generation (Hein and Simon 2019). In both clade I and clade II NosZs, proton motive quinol oxidation by N2O is thought to be catalyzed by the Q cycle mechanism of a membrane-bound Rieske/cytochrome bc complex (Hein and Simon 2019). Nitrous-oxide reductase is part of a bacterial
respiratory system which is activated under anaerobic conditions in the
presence of nitrate or nitrous oxide. NosZ is similar in sequence to cytochrome c oxidase component 2 only in the C-terminal 100 aa residues of both proteins which contains a pair of cysteyl residues. | Bacteria |
Pseudomonadota | NosZ of Paracoccus denitrificans |
|
3.D.4.3.1 | Cytochrome oxidase | Archaea |
Euryarchaeota | Coxl,2 of Halobacterium halobium Cox1 (P33518) Cox2 (AAC82824) |
|
3.D.4.3.2 | Cytochrome bd quinol oxidoreductase, CydA/CydB. Borisov et al. (2011) have presented evidence concerning a proton channel connecting the site of oxygen reduction to the bacteria cytoplasm and the molecular mechanism by which a membrane potential is generated. The CydX protein of 37 aas and 1 TMS, is encoded in the cydAB operon and functions as a subunit of the Cytochrome bd oxidase complex, activating its activity (VanOrsdel et al. 2013). The AppX protein of 30 aas and 1 TMS, is a paralogue of CydX and can substitute for it in activating the Cytochrome bd oxidase complex (VanOrsdel et al. 2013). Cytochrome bd-type quinol oxidases are structurally unrelated to mitochondrial cytochrome c oxidases. Safarian et al. 2019 determined the structure of the E. coli cytochrome bd-I oxidase by single-particle cryo-electron microscopy to a resolution of 2.7 angstroms. The structure contains a previously unknown accessory subunit CydH, the L-subfamily-specific Q-loop domain, a structural ubiquinone-8 cofactor, an active-site density interpreted as dioxygen, distinct water-filled proton channels, and an oxygen-conducting pathway. Comparison with another cytochrome bd oxidase revealed structural divergence in the family, including rearrangement of high-spin hemes and conformational adaption of a transmembrane helix to generate a distinct oxygen-binding site (Safarian et al. 2019). Subunit I of the cytochrome bd quinol oxidase from E. coli has nine transmembrane helices with the O2 reactive site near the periplasmic surface (Zhang et al. 2004). Two small proteins, YtkA (CtaK; 145 aas; P40768) and YczB (CtaM; 70 aas; O31467; TatAd) facilitate the biogenesis of cytochrome c oxidase in Bacillus subtilis (von Wachenfeldt et al. 2021). The latter protein may alsVanOrsdel et al. 2013). The AppX protein of 30 aas and 1 TMS, is a paralogue of CydX and can substitute for it in activating the Cytochrome bd oxidase complex (VanOrsdel et al. 2013). Cytochrome bd-type quinol oxidases are structurally unrelated to mitochondrial cytochrome c oxidases. Safarian et al. 2019 determined the structure of the E. coli cytochrome bd-I oxidase by single-particle cryo-electron microscopy to a resolution of 2.7 angstroms. The structure contains a previously unknown accessory subunit CydH, the L-subfamily-specific Q-loop domain, a structural ubiquinone-8 cofactor, an active-site density interpreted as dioxygen, distinct water-filled proton channels, and an oxygen-conducting pathway. Comparison with another cytochrome bd oxidase revealed structural divergence in the family, including rearrangement of high-spin hemes and conformational adaption of a transmembrane helix to generate a distinct oxygen-binding site (Safarian et al. 2019). Subunit I of the cytochrome bd quinol oxidase from E. coli has nine transmembrane helices with the O2 reactive site near the periplasmic surface (Zhang et al. 2004). Two small proteins, YtkA (CtaK; 145 aas; P40768) and YczB (CtaM; 70 aas; O31467; TatAd) facilitate the biogenesis of cytochrome c oxidase in Bacillus subtilis (von Wachenfeldt et al. 2021). The latter protein may also function as a constituent of the Tat system (TC# 2.A.64.3.1).
| Bacteria |
Pseudomonadota | CydA/CydB/CydX/AppX of E. coli CydA (P0ABJ9) CydB (P0ABK2) CydX (P56100) AppX (P24244) CydH (YnhF) (A5A618) |
|
3.D.4.3.3 | Cbb3 cytochrome c oxidase (COX; Cbb3; CcoNOP). The 3-d structure is known to 3.2 Å resolution (PDB# 3MK7; 5DJQ) (Buschmann et al. 2010; Lee et al., 2012). The structure explains a proton-pumping mechanism and the high activity of family-C heme-copper oxidases compared to that of families A and B (Buschmann et al., 2010; Lee et al., 2012). A small subunit of 36 aas and 1 TMS, CcoM, was identified in the structure and plays a role in assembly and stability (Kohlstaedt et al. 2016; Carvalheda and Pisliakov 2017). CcoQ, another small protein of 62 aas (acc # F8H837) is an assembly factor for Cbb3-1 and Cbb3-2 (Kohlstaedt et al. 2017). The A-, B- and C-type oxygen reductases each have an active-site tyrosine that forms a unique cross-linked histidine-tyrosine cofactor. In the C-type oxygen reductases (also called cbb3 oxidases), this post-translationally generated co-factor occurs in a different TMS than for the A- and B-type reductases (Hemp et al. 2006). | Bacteria |
Pseudomonadota | CcoNOP of Pseudomonas stutzeri CcoN (Chain A) (H7F0T0) CcoO (Chain B) (F8H841) CcoP (Chain C) (D9IA45) CcoM (Chain D) (H7ESS5) CcoQ (assembly factor) (Q8KS20) |
|
3.D.4.3.4 | Cytochrome oxidase subunit I (CydA) of 481 aas and 9 or 10 TMSs, and subunit II (CydB) of 337 aas and 9 TMSs (Soo et al. 2017). | Bacteria |
Cyanobacteriota | CydAB of Thermosynechococcus elongatus |
|
3.D.4.3.5 | Cytochrome bd, AppB (CbdB, CyxB) of 378 aas and 9 TMSs. It is a terminal oxidase that catalyzes quinol-dependent, Na+-independent oxygen uptake. It prefers menadiol over other quinols although ubiquinol was not tested (Sturr et al. 1996). It generates a proton motive force using protons and electrons from opposite sides of the membrane to generate H2O, transferring 1 proton/electron. The mechanism of generation of a transmembrane electric potential difference (Deltapsi) during the catalytic cycle of a bd-type triheme terminal quinol oxidase hasbeen reviewed (Borisov 2023). | Bacteria |
Pseudomonadota | Cyt bd of E. coli |
|
3.D.4.4.1 | Cytochrome oxidase including heme A synthase (HAS) and 4 subunits of the cytochrome oxidase. The 3-d structure of heme A synthase (of 306 aas and 8 TMSs) at 2.2 Å resolution has been solved revealing that the N- and C-terminal halves of HAS consist of four-helix bundles and they align in a pseudo twofold symmetry manner. Each bundle contains a pair of histidine residues and forms a heme-binding domain. The C-half domain binds a cofactor-heme molecule, while the N-half domain is vacant (Niwa et al. 2018). The Sco1 protein, YpmQ, is an accessory protein involved in the assembly of cytochrome c oxidase (Andrews et al. 2004). | Bacteria |
Bacillota | CtaACDEF of Bacillus subtilis |
|
3.D.4.4.2 | Cytochrome c oxidase (Cytaa3, subunits 1-4) (Niebisch and Bott, 2003) | Bacteria |
Actinomycetota | Cytaa3 of Corynebacterium glutamicum subunit I (584 aas) (Q79VD7) subunit II (359 aas) (Q8NNK2) subunit III (205 aas) (Q9AEL8) subunit IV (143 aas) (Q8NNK3) |
|
3.D.4.4.3 | The proton pumping Caa3-type cytochrome oxidase chains A-F. The crystal structure (PDB: 2YEV) is known (2.36Å resolution; Lyons et al., 2012). It has a covalently teathered cytochrome c domain. In the cytochrome aa3, O2 molecules that arrive at the reduction site diffuse through the X-ray-observed tunnel, supporting its role as the main O2 delivery pathway in this cytochrome ba3 as well as the cytochrome aa3 of Rhodobacter spheroides (Mahinthichaichan et al. 2018). | Bacteria |
Deinococcota | Caa(3)-type cytochrome oxidase of Thermus thermophilus Subunit I + III, Chain A 791aas; 19 TMSs. (P98005) Subunit II; Chain B 337aas; 2 TMSs. (Q5SLI2) Subunit IV; Chain C 66aas; 2 TMSs. (Q5SH67) |
|
3.D.4.4.4 | Cytochrome c oxidase, subunits CtaC (337 aas) CtaD (552 aas) and CtaE (201 aas) (also called CoxABC; Soo et al. 2017). | Bacteria |
Cyanobacteriota | CtaCDE of Thermosynechococcus elongatus |
|
3.D.4.4.5 | Cytochrome oxidase complex, CtaCDEF with CtaC being subunit 2 or Cox2 (319 aas and 3 TMSs), CtaD being subunit 1 or Cox1 (578 aas and 12 TMSs), CtaE being subunit 3 or Cox3 (206 aas and 5 TMSs), and CtaF being subunit 4 or Cox4 (132 aas with 4 TMSs in a 2 + 2 TMS arrangement). This complex forms a supercomplex with QcrABC (TC# 3.D.3.5.4) (Falke et al. 2018). The supercomplex is required for nitrate reductase 1 activity and is encoded within a single gene cluster (Falke et al. 2019). | Bacteria |
Actinomycetota | CtaCDEF of Streptomyces coelicolor |
|
3.D.4.5.1 | Quinol oxidase (CyoABCD). This cytochrome bo3 ubiquinol oxidase is a transmembrane protein of 663 aas and 14 or 15 TMSs, which oxidizes ubiquinone and reduces oxygen, while pumping protons (Marušič et al. 2020). The cytochrome bo3 complex is the component of the aerobic respiratory chain of E. coli that predominates when cells are grown under high aeration conditions. It has proton pumping activity, pumping 2 protons/electron. Protons are probably pumped via D- and K-channels found in the cyoB subunit (Abramson et al. 2000). Two independent structures of the proton-pumping, respiratory cytochrome bo 3 ubiquinol oxidase (cytbo3) have been determined by cryo-EM in styrene-maleic acid (SMA) copolymer nanodiscs and in membrane scaffold protein (MSP) nanodiscs to 2.55- and 2.19-Å resolution, respectively (Li et al. 2021). The structures include the metal redox centers (heme b, heme o3 , and CuB), the redox-active cross-linked histidine-tyrosine cofactor, and the internal water molecules in the proton-conducting D channel. Each structure also contains one equivalent of ubiquinone-8 (UQ8) in the substrate binding site as well as several phospholipid molecules. The isoprene side chain of UQ8 is clamped within a hydrophobic groove in subunit I by TMS0, which is only present in quinol oxidases and not in the closely related cytochrome c oxidases. Both structures show carbonyl O1 of the UQ8 headgroup hydrogen bonded to D75(I) and R71(I). In both structures, residue H98(I) occupies two conformations. In conformation 1, H98(I) forms a hydrogen bond with carbonyl O4 of the UQ8 headgroup, but in conformation 2, the imidazole side chain of H98(I) has flipped to form a hydrogen bond with E14(I) at the N-terminal end of TMS0. The authors proposed that H98(I) dynamics facilitate proton transfer from ubiquinol to the periplasmic aqueous phase during oxidation of the substrate. Computational studies show that TMS0 creates a channel, allowing access of water to the ubiquinol headgroup and to H98(I) (Li et al. 2021). Jose et al. 2021 investigated the key PM intermediate, which forms after O–O bond cleavage and precedes proton pumping, using magnetic circular dichroism spectroscopy. The authors observed features demonstrating that PM is a three-spin system, consistent with a consensus model including an iron(IV)-oxo species, a copper(II) ion, and a tyrosyl radical. These results provide validation of the O–O cleavage mechanism and open the door to understanding the proton pumping step (Jose et al. 2021).
| Bacteria |
Pseudomonadota | CyoABCD of E. coli CyoA, 315 aas and 3 N-terminal TMSs CyoB, 663 aas and 14 TMSs CyoC, 204 aas and 5 TMSs CyoD, 109 aas and 3 TMSs |
|
3.D.4.5.2 | Cytochrome aa3 quinol oxidase subunits I- IV (E - H). The 3-D structure has been determined (PDB# 6KOE). The quinol oxidases have an additional transmembrane helix (TMS0) in subunit I that is not present in the related cytochrome c oxidases. Xu et al. 2020 reported the 3.6 Å-resolution X-ray structure of the cytochrome aa3-600 menaquinol oxidase from Bacillus subtilis containing 1 equivalent of menaquinone. The structure shows that TM0 forms part of a cleft to accommodate the menaquinol-7 substrate. Crystals which had been soaked with the quinol-analog inhibitor HQNO (N-oxo-2-heptyl-4-hydroxyquinoline) or 3-iodo-HQNO revealed a single binding site where the inhibitor forms hydrogen bonds to amino acid residues shown previously by spectroscopic methods to interact with the semiquinone state of menaquinone, a catalytic intermediate (Xu et al. 2020). | Bacteria |
Bacillota | Cytochrome aa3 quinol oxidase subunits I- IV (E - H) of Bacillus subtilis Subunit I (1 or E) of 649 aas and 14 - 16 TMSs, WP_063334853.1 Subunit II (2 or F) of 296 aas and 3 TMSs, WP_003227405 Subunit III (3 or G) of 204 aas and 5 TMSs, WP_088327222 Subunit IV (4 or H) of 123 aas and 3 TMSs, WP_069837848.1 |
|
3.D.4.6.1 | Cytochrome oxidase (CtaBD/CycA) | Bacteria |
Pseudomonadota | CtaBD/CycA of Paracoccus denitrificans CtaB (subunit 2) (P08306) CtaD (subunit 1) (P98002) CycA (P00096) |
|
3.D.4.6.2 | Cytochrome c aa3 oxidase (COX). The 3-d structure is known (PDB# 1M56) (Lee et al., 2012). There are three hydrophobic channels connecting the hydrophobic membrane through the protein to the heme A3/CuB binuclear center (BNC), two of which are probably preferred for O2 diffusion (Oliveira et al. 2014). The D channel is the proton transporting channel, and mutations in residues along this channel, especially N139 in subunit 1, uncouple H+ transport from electron flow (Han et al. 2005). Liang et al. 2017 provided insight into the decoupling mechanisms of CcO mutants, and explained how kinetic gating in the D-channel is imperative to achieving high proton-pumping efficiency in the WT CcO. The O2 molecules that arrived in the reduction site diffuse through the X-ray-observed tunnel, despite its apparent constriction, supporting its role as the main O2 delivery pathway in cytochrome aa3 (Mahinthichaichan et al. 2018). | Bacteria |
Pseudomonadota | COX chains A-D of Rhodobacter spheroides Chain A (P33517) Chain B (Q03736) Chain C (Q3J5F6) Chain D (Q3IZW6) |
|
3.D.4.7.1 | Cytochrome oxidase (Cox1-3). A radical in the peroxide-produced F-type ferryl form of bovine cytochrome c oxidase has been identified (Sztachova et al. 2022). | Eukaryota |
Metazoa, Chordata | Coxl-3 of Bos taurus |
|
3.D.4.8.1 | Cytochrome oxidase (Cox). The Plasmodium falciparum putative SURF1 protein can functionally replace SHY1, a COX assembly factor of complex IV of the mitochondrial electron transfer complex of Saccharomyces cerevisiae (Chellappan et al. 2021). | Eukaryota |
Fungi, Ascomycota | Cytochrome oxidase (Cox) of Saccharomyces cerevisiae Cox1p; Cox subunit I [Q0045] (NP_009305) Cox2p; Cox subunit II [Q0250] (NP_009326) Cox3p; Cox subunit III [Q0275] (NP_009328) Cox4p; Cox subunit IV [YGL187c] (NP_011328) Cox5Ap; Cox subunit Va [YNL052w] (aerobically induced) (NP_014346) Cox5Bp; Cox subunit Vb [YIL111w] (anaerobically induced) (NP_012155) Cox6p; Cox subunit VI [YHR051w] (NP_011918) Cox7p; Cox subunit VII [YMR256c] (NP_013983) Cox8p; Cox subunit VIII [YLR395c] (NP_013499) Cox9p; Cox subunit VIIa [YDL067c] (NP_010216) Cox11p; Cox assembly protein [YPL132w] (NP_015193) Cox12p; Cox subunit VIb [YLR038c] (NP_013139) Cox13p; Cox subunit VIa [YGL191w] (NP_011324) Shylp; Cox chaperone [YGR112w] (NP_011627) |
|
3.D.4.9.1 | Quinol oxidase (proton gradient generated only by chemical charge separation) (Purschke et al., 1997) [DoxA + DoxD comprise a novel membrane-bound thiosulfate: quinone oxidoreductase, Dox (Müller et al., 2004)] | Archaea |
Thermoproteota | DoxABCDEF of Acidianus ambivalens DoxA (173 aas) (CAA69987) DoxB (587 aas) (CAA69980) DoxC (344 aas) (CAA69981) DoxD (174 aas) (CAA69986) DoxE (64 aas) (CAA69982) DoxF (67 aas) (CAA69983) |
|
3.D.4.10.1 | Nitric oxide reductase (EC #1.7.99.7) (NorBC) (component of the anerobic, respiratory chain that converts NO3- to N2; denitrification) [reaction catalyzed by Nor: 2 nitric oxide (NO) + 2e- + 2H+ → nitrous oxide (N20) + H2O]. This enzyme does not pump protons across the bacterial membrane (Reimann et al. 2007), but the protons needed for the reaction are taken from the periplasmic side of the membrane (from which side the electrons are donated). P. denitrificans NOR uses a single defined proton pathway with residues Glu-58 and Lys-54 from the NorC subunit at the entrance (ter Beek et al. 2016). norC and norB encode the cytochrome-c-containing subunit II and cytochrome b-containing subunit I of nitric-oxide reductase (NO reductase), respectively. norQ encodes a protein with an ATP-binding motif and is similar to NirQ from Pseudomonas stutzeri and Pseudomonas aeruginosa and CbbQ from Pseudomonas hydrogenothermophila. norE encodes a protein with five putative transmembrane alpha-helices and has similarity to CoxIII, the third subunit of the aa3-type cytochrome-c oxidases. norF encodes a small protein with two putative transmembrane alpha-helices. Mutagenesis of norC, norB, norQ or norD resulted in cells unable to grow anaerobically. Nitrite reductase and NO reductase (with succinate or ascorbate as substrates) and nitrous oxide reductase (with succinate as substrate) activities were not detected in these mutant strains. Nitrite extrusion was detected in the medium, indicating that nitrate reductase was active. The norQ and norD mutant strains retained about 16% and 23% of the wild-type level of NorC, respectively. The norE and norF mutant strains had specific growth rates and NorC contents similar to those of the wild-type strain, but had reduced NOR and NIR activities, indicating that their gene products are involved in regulation of enzyme activity (de Boer et al. 1996). | Bacteria |
Pseudomonadota | NorBC of Paracoccus denitrificans NorB (Q51603; 462 aas; 12 TMSs) NorC (Q51662; 150 aas; 1 N-terminal TMS) NorD (Q51665;638 aas; 0 TMSs) NorE (Q51666; 167 aas; 5 TMSs) NorF (Q51667; 77 aas and 2 TMSs) |
|
3.D.4.10.2 | Bacterial respiratory, anaerobic, nitric oxide reductase (NorBC) (not a proton pump; Flock et al., 2008 ) | Bacteria |
Pseudomonadota | NorBC of Pseudomonas stutzeri NorB (cytochrome b subunit; 474 aas) (P98008) NorC (cytochrom c subunit, 146 aas) (Q52527) |
|
3.D.4.10.3 | Nitric oxide reductase, NorBC. 3-d structure known (PDB# 3o0R) (Lee et al., 2012) | Bacteria |
Pseudomonadota | NorBC of Pseudomonas aeruginosa NorB (Chain B) (Q59647) NorC (Chain C) (Q59646) |
|
3.D.4.10.4 | Nitric oxide reductase of 787 aas and 14 TMSs, NorZ. This copper-A-dependent NOR uses cytochrome c₅₅₁ as electron donor but lacks menaquinol activity (Al-Attar and de Vries 2015). Employing reduced phenazine ethosulfate (PESH) as electron donor, the main NO reduction pathway catalyzed by Cu(A)Nor reconstituted in liposomes involves transmembrane cycling of the PES radical. Cu(A)Nor reconstituted in liposomes generates a proton electrochemical gradient across the membrane similar in magnitude to cytochrome aa₃, suggesting that bacilli using Cu(A)Nor to exploit NO reduction to increase cellular ATP production (Al-Attar and de Vries 2015). | Bacillota | NOR of Bacillus azotoformans | |
|
3.D.4.10.5 | Nitric oxide reductase large subunit, NorB, of 753 aas and 14 TMSs (Al-Attar and de Vries 2015). | Bacillota | NorB of Bacillus azotoformans | |
|
3.D.4.11.1 | Cytochrome oxidase (Cox or CcO). Reversible hydration-level changes of the cavity can be a key factor that regulates the branching of proton transfer events and therefore contributes to the vectorial efficiency of proton transport (Son et al. 2017). Cox16 is required for the assembly of the mitochondrial cytochrome c oxidase (respiratory chain complex IV (CIV)), possibly by promoting the insertion of copper into the active site of cytochrome c oxidase subunit II (MT-CO2/COX2) (Cerqua et al. 2018; Aich et al. 2018). Lipid composition affects the efficiency of the functional reconstitution of the cytochrome c oxidase (Hugentobler et al. 2020). The DeepCys program has been used to predict the functions of cysteine residues in Cox2 (Nallapareddy et al. 2021). | Eukaryota |
Metazoa, Chordata | Cox of Homo sapiens (CoxI-VIII3) CoxI (Cox1) (P00395) CoxII (Cox2) (P00403) CoxIII (Cox3) (P00414) CoxIV-1 (isoform 1) (Cox41) (P13073) CoxIV-2 (isoform 2) (Cox42) (Q96KJ9) CoxVa (Cox5a) (P20674) CoxVb (Cox5b) (P10601) CoxVIa (Cox6A2) (Q02221) CoxVIb (Cox6B2) (Q6YFQ2) CoxVIIa-H (Cox7A1) (P24310) CoxVIIa-L (Cox7A2) (P14406) CoxVIIb2 (Cox7B2) (Q8TF08) CoxVIIc (Cox7c) (P15954) CoxVIII-1 (Cox 81) (P48772) (Mouse; human not available) CoxVIII-2 (Cox82) (P10176) CoxVIII-3 (Cox83) (Q7Z4L0) Cox 16, auxillary subunit (Q9P0S2) |
|
3.D.4.12.1 | Cytochrome ubiquinol oxidase subunits I and II of 878 aas and 8 or 9 N-terminal TMSs (I), and 342 aas and 9 TMSs. While subunit I is very distant to many other subunits I from other bacteria, subunit II is much more similar. | Bacteria |
Thermodesulfobacteriota | Cyt Ox of Desulfococcus multivorans |