Quinol Oxidase Research Articles

Thiobacillus sedimenti sp. nov., a chemolithoautotrophic sulphur-oxidizing bacterium isolated from freshwater sediment.

A sulphur-oxidizing bacterium, designated strain SCUT-2T, was isolated from freshwater sediment collected from the Pearl River in Guangzhou, PR China. This strain was an obligate chemolithoautotroph, utilizing reduced sulphur compounds (elemental sulphur, thiosulphate, tetrathionate and sulphite) as the electron donor. Growth of strain SCUT-2T was observed at 20-40℃ (optimum at 30°C), pH 5.0-9.0 (optimum at 6.0), and NaCl concentration range of 0-9gL-1 (optimum at 1gL-1). The major cellular fatty acids were C16:0 ω7c and cyclo-C17:0. The DNA G + C content of the complete genome sequence was 66.8 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain SCUT-2T formed a lineage within the genus Thiobacillus, showing gene sequence identity of 98.0% with its closest relative Thiobacillus thioparus THI 115. The genome of strain SCUT-2T contains multiple genes encoding sulphur-oxidizing enzymes that catalyse the oxidation of reduced sulphur compounds, partial genes that are necessary for denitrification, and the genes encoding cbb3-type cytochrome c oxidase, aa3-type cytochrome c oxidase and bd-type quinol oxidase. Facultative anaerobic growth occurs when using nitrate as the electron acceptor and thiosulphate as the electron donor. On the basis of phenotypic, chemotaxonomic, genotypic and phylogenetic analysis, strain SCUT-2T (= GDMCC 1.4108T = JCM 39443T) is deemed to represent a novel Thiobacillus species, for which we propose the name Thiobacillus sedimenti sp. nov.

The two-component regulatory systems GraRS and SrrAB mediate Staphylococcus aureus susceptibility to Pep5 produced by clinical isolate of Staphylococcus epidermidis.

Staphylococcus aureus is a common bacterium on the skin and in the nose that sometimes causes severe illness. Bacteriocins, antimicrobial peptides, or proteins produced by bacteria are candidates for the treatment of S. aureus infection. In this study, we found that a clinical Staphylococcus epidermidis strain, KSE112, produced the lantibiotic Pep5, which showed anti-S. aureus activity. The complete nucleotide sequence of the Pep5-encoding plasmid was determined. Several S. aureus two-component regulatory systems (TCSs) are known to be involved in bacteriocin susceptibility. Therefore, susceptibility tests were performed using TCS-inactivated S. aureus mutants to determine which TCS is responsible for Pep5 susceptibility; the ΔgraRS mutant exhibited increased susceptibility to Pep5, while the ΔsrrAB mutant exhibited decreased susceptibility. GraRS is known to regulate dltABCD and mprF in concert with vraFG, and Pep5 susceptibility was significantly increased in the ΔdltABCD, ΔmprF, and ΔvraFG mutants. Regarding the ΔsrrAB mutant, cross-resistance to aminoglycosides was observed. As aminoglycoside activity is known to be affected by aerobic respiration, we focused on qoxABCD and cydAB, which are quinol oxidase genes that are necessary for aerobic respiration and have downregulated the expression in the ΔsrrAB mutant. We constructed ΔqoxABCD and ΔcydAB mutants and found that qoxABCD inactivation decreased susceptibility to Pep5 and aminoglycosides. These results indicate that reduced aerobic respiration due to the reduced qoxABCD expression in the ΔsrrAB mutant decreased Pep5 activity.IMPORTANCEThe emergence of drug-resistant bacteria, including MRSA, is a severe health problem worldwide. Thus, the development of novel antimicrobial agents, including bacteriocins, is needed. In this report, we found a Pep5-producing strain with anti-S. aureus activity. We determined the complete sequence of the Pep5-encoding plasmid for the first time. However, in S. aureus, GraRS and its effectors conferred decreased susceptibility to Pep5. We also revealed that another TCS, SrrAB, affects susceptibility Pep5 and other lantibiotics by controlling aerobic respiration. In our study, we investigated the efficacy of Pep5 against S. aureus and other Gram-positive bacteria and revealed that respiratory constancy regulated by TCS is required for the antimicrobial activity of nisin, nukacin, and Pep5. These findings provide important information for the clinical application of bacteriocins and suggest that they have different properties among similar pore-forming lantibiotics.

Cryo-EM structure of cytochrome bo3 quinol oxidase assembled in peptidiscs reveals an “open” conformation for potential ubiquinone-8 release

Cytochrome bo3 quinol oxidase belongs to the heme‑copper-oxidoreductase (HCO) superfamily, which is part of the respiratory chain and essential for cell survival. While the reaction mechanism of cyt bo3 has been studied extensively over the last decades, specific details about its substrate binding and product release have remained unelucidated due to the lack of structural information. Here, we report a 2.8 Å cryo-electron microscopy structure of cyt bo3 from Escherichia coli assembled in peptidiscs. Our structural model shows a conformation for amino acids 1–41 of subunit I different from all previously published structures while the remaining parts of this enzyme are similar. Our new conformation shows a “U-shape” assembly in contrast to the transmembrane helix, named “TM0”, in other reported structural models. However, TM0 blocks ubiquinone-8 (reaction product) release, suggesting that other cyt bo3 conformations should exist. Our structural model presents experimental evidence for an “open” conformation to facilitate substrate/product exchange. This work helps further understand the reaction cycle of this oxidase, which could be a benefit for potential drug/antibiotic design for health science.

Recent mechanistic developments for cytochrome c nitrite reductase, the key enzyme in the dissimilatory nitrate reduction to ammonium pathway

Cytochrome c nitrite reductase, NrfA, is a soluble, periplasmic pentaheme cytochrome responsible for the reduction of nitrite to ammonium in the Dissimilatory Nitrate Reduction to Ammonium (DNRA) pathway, a vital reaction in the global nitrogen cycle. NrfA catalyzes this six-electron and eight-proton reduction of nitrite at a single active site with the help of its quinol oxidase partners. In this review, we summarize the latest progress in elucidating the reaction mechanism of ammonia production, including new findings about the active site architecture of NrfA, as well as recent results that elucidate electron transfer and storage in the pentaheme scaffold of this enzyme.

Identification of novel tail-anchored membrane proteins integrated by the bacterial twin-arginine translocase.

The twin-arginine protein transport (Tat) system exports folded proteins across the cytoplasmic membranes of prokaryotes and the energy transducing-membranes of plant thylakoids and mitochondria. Proteins are targeted to the Tat machinery by N-terminal signal peptides with a conserved twin-arginine motif, and some substrates are exported as heterodimers where the signal peptide is present on one of the partner proteins. A subset of Tat substrates is found in the membrane. Tat-dependent membrane proteins usually have large globular domains and a single transmembrane helix present at the N- or C-terminus. Five Tat substrates that have C-terminal transmembrane helices have previously been characterized in the model bacterium Escherichia coli. Each of these is an iron-sulfur cluster-containing protein involved in electron transfer from hydrogen or formate. Here we have undertaken a bioinformatic search to identify further tail-anchored Tat substrates encoded in bacterial genomes. Our analysis has revealed additional tail-anchored iron-sulfur proteins associated in modules with either a b-type cytochrome or a quinol oxidase. We also identified further candidate tail-anchored Tat substrates, particularly among members of the actinobacterial phylum, that are not predicted to contain cofactors. Using reporter assays, we show experimentally that six of these have both N-terminal Tat signal peptides and C-terminal transmembrane helices. The newly identified proteins include a carboxypeptidase and a predicted protease, and four sortase substrates for which membrane integration is a prerequisite for covalent attachment to the cell wall.

Membrane-Bound Redox Enzyme Cytochrome bd-I Promotes Carbon Monoxide-Resistant Escherichia coli Growth and Respiration.

The terminal oxidases of bacterial aerobic respiratory chains are redox-active electrogenic enzymes that catalyze the four-electron reduction of O2 to 2H2O taking out electrons from quinol or cytochrome c. Living bacteria often deal with carbon monoxide (CO) which can act as both a signaling molecule and a poison. Bacterial terminal oxidases contain hemes; therefore, they are potential targets for CO. However, our knowledge of this issue is limited and contradictory. Here, we investigated the effect of CO on the cell growth and aerobic respiration of three different Escherichia coli mutants, each expressing only one terminal quinol oxidase: cytochrome bd-I, cytochrome bd-II, or cytochrome bo3. We found that following the addition of CO to bd-I-only cells, a minimal effect on growth was observed, whereas the growth of both bd-II-only and bo3-only strains was severely impaired. Consistently, the degree of resistance of aerobic respiration of bd-I-only cells to CO is high, as opposed to high CO sensitivity displayed by bd-II-only and bo3-only cells consuming O2. Such a difference between the oxidases in sensitivity to CO was also observed with isolated membranes of the mutants. Accordingly, O2 consumption of wild-type cells showed relatively low CO sensitivity under conditions favoring the expression of a bd-type oxidase.

Proteins of the food-borne pathogen <i>Listeria monocytogenes</i> strain F2365 relevant to lethal acidic stress and during rapid inactivation

<abstract> <p><italic>Listeria monocytogenes</italic>, which causes human listeriosis after consumption of contaminated food, can adapt and survive under a wide range of physiological and chemical stresses. In this study, the overall proteomic response of the <italic>L. monocytogenes</italic> strain F2365—a strain with mutations limiting its ability to tolerate acidic conditions—to progressive non-thermal acidic inactivation was investigated. The challenge process was investigated in the early stationary growth phase where F2365 cultures were acidified (pH 3.0, HCl) at 5 min, 1 h, and 2 h, generating pH 4.8, pH 4.1, and pH 3.5, respectively, with protein abundance measured using iTRAQ. Approximately 73 proteins increased in abundance and 8 declined when acidic stress became non-growth-permissive (pH < 4.1) and inactivation accelerated to approximately 2 log units/h. The functional categories of responding proteins were broad but the proteins involved were specific in nature and did not include whole pathways. Many responses likely accentuate energy conservation and compensate vital metabolic processes. For example, further repression of FlaA, normally repressed under acidic stress, occurs accompanied by an increase in quinol oxidase subunit QoxA and glycerol kinase GlpK. Proteins maintaining cell wall integrity, such as Iap and CwlO, manifested the overall largest abundance increase trend. Virulence proteins were also induced, including InlA, InlC, Hyl, Mpl, PlcA, and PlcB, suggesting that acidification may have mimicked conditions inducing some host survival traits. The overall suite of proteins affected appears to be the "last ditch" responses to non-thermal inactivation above and beyond the standard protections afforded in the stationary-growth phase. The array of proteins found here may provide a deeper understanding of the physiological responses of this pathogen during non-thermal inactivation.</p> </abstract>

Membrane potential generation by cytochrome <i>bd</i>

This treatise gives an overview of current thinking on the mechanism of generation of a transmembrane electric potential difference (Δψ) during the catalytic cycle of a bd-type triheme terminal quinol oxidase. It is assumed that the main contribution to the Δψ formation is made by the movement of H+ across the membrane along the intraprotein hydrophilic proton-conducting pathway from the cytoplasm to the active site for oxygen reduction of this bacterial enzyme.

The Escherichia coli MFS-type transporter genes yhjE, ydiM, and yfcJ are required to produce an active bo3 quinol oxidase.

Heme-copper oxygen reductases are membrane-bound oligomeric complexes that are integral to prokaryotic and eukaryotic aerobic respiratory chains. Biogenesis of these enzymes is complex and requires coordinated assembly of the subunits and their cofactors. Some of the components are involved in the acquisition and integration of different heme and copper (Cu) cofactors into these terminal oxygen reductases. As such, MFS-type transporters of the CalT family (e.g., CcoA) are required for Cu import and heme-CuB center biogenesis of the cbb3-type cytochrome c oxidases (cbb3-Cox). However, functionally homologous Cu transporters for similar heme-Cu containing bo3-type quinol oxidases (bo3-Qox) are unknown. Despite the occurrence of multiple MFS-type transporters, orthologs of CcoA are absent in bacteria like Escherichia coli that contain bo3-Qox. In this work, we identified a subset of uncharacterized MFS transporters, based on the presence of putative metal-binding residues, as likely candidates for the missing Cu transporter. Using a genetic approach, we tested whether these transporters are involved in the biogenesis of E. coli bo3-Qox. When respiratory growth is dependent on bo3-Qox, because of deletion of the bd-type Qox enzymes, three candidate genes, yhjE, ydiM, and yfcJ, were found to be critical for E. coli growth. Radioactive metal uptake assays showed that ΔydiM has a slower 64Cu uptake, whereas ΔyhjE accumulates reduced 55Fe in the cell, while no similar uptake defect is associated with ΔycfJ. Phylogenomic analyses suggest plausible roles for the YhjE, YdiM, and YfcJ transporters, and overall findings illustrate the diverse roles that the MFS-type transporters play in cellular metal homeostasis and production of active heme-Cu oxygen reductases.

Generation of Membrane Potential by Cytochrome bd.

An overview of current notions on the mechanism of generation of a transmembrane electric potential difference (Δψ) during the catalytic cycle of a bd-type triheme terminal quinol oxidase is presented in this work. It is suggested that the main contribution to Δψ formation is made by the movement of H+ across the membrane along the intra-protein hydrophilic proton-conducting pathway from the cytoplasm to the active site for oxygen reduction of this bacterial enzyme.

Exploring ND-011992, a quinazoline-type inhibitor targeting quinone reductases and quinol oxidases

Bacterial energy metabolism has become a promising target for next-generation tuberculosis chemotherapy. One strategy to hamper ATP production is to inhibit the respiratory oxidases. The respiratory chain of Mycobacterium tuberculosis comprises a cytochrome bcc:aa3 and a cytochrome bd ubiquinol oxidase that require a combined approach to block their activity. A quinazoline-type compound called ND-011992 has previously been reported to ineffectively inhibit bd oxidases, but to act bactericidal in combination with inhibitors of cytochrome bcc:aa3 oxidase. Due to the structural similarity of ND-011992 to quinazoline-type inhibitors of respiratory complex I, we suspected that this compound is also capable of blocking other respiratory chain complexes. Here, we synthesized ND-011992 and a bromine derivative to study their effect on the respiratory chain complexes of Escherichia coli. And indeed, ND-011992 was found to inhibit respiratory complex I and bo3 oxidase in addition to bd-I and bd-II oxidases. The IC50 values are all in the low micromolar range, with inhibition of complex I providing the lowest value with an IC50 of 0.12 µM. Thus, ND-011992 acts on both, quinone reductases and quinol oxidases and could be very well suited to regulate the activity of the entire respiratory chain.

The terminal oxidase cytochrome bd-I confers carbon monoxide resistance to Escherichia coli cells

Carbon monoxide (CO) plays a multifaceted role in the physiology of organisms, from poison to signaling molecule. Heme proteins, including terminal oxidases, are plausible CO targets. Three quinol oxidases terminate the branched aerobic respiratory chain of Escherichia coli. These are the heme‑copper cytochrome bo3 and two copper-lacking bd-type cytochromes, bd-I and bd-II. All three enzymes generate a proton motive force during the four-electron oxygen reduction reaction that is used for ATP production. The bd-type oxidases also contribute to mechanisms of bacterial defense against various types of stresses. Here we report that in E. coli cells, at the enzyme concentrations tested, cytochrome bd-I is much more resistant to inhibition by CO than cytochrome bd-II and cytochrome bo3. The apparent half-maximal inhibitory concentration values, IC50, for inhibition of O2 consumption of the membrane-bound bd-II and bo3 oxidases by CO at ~150 μM O2 were estimated to be 187.1 ± 11.1 and 183.3 ± 13.5 μM CO, respectively. Under the same conditions, the maximum inhibition observed with the membrane-bound cytochrome bd-I was 20 ± 10% at ~200 μM CO.

Respiratory complex I in mitochondrial membrane catalyzes oversized ubiquinones

NADH-ubiquinone (UQ) oxidoreductase (complex I) couples electron transfer from NADH to UQ with proton translocation in its membrane part. The UQ reduction step is key to triggering proton translocation. Structural studies have identified a long, narrow, tunnel-like cavity within complex I, through which UQ may access a deep reaction site. To elucidate the physiological relevance of this UQ-accessing tunnel, we previously investigated whether a series of oversized UQs (OS-UQs), whose tail moiety is too large to enter and transit the narrow tunnel, can be catalytically reduced by complex I using the native enzyme in bovine heart submitochondrial particles (SMPs) and the isolated enzyme reconstituted into liposomes. Nevertheless, the physiological relevance remained unclear because some amphiphilic OS-UQs were reduced in SMPs but not in proteoliposomes, and investigation of extremely hydrophobic OS-UQs was not possible in SMPs. To uniformly assess the electron transfer activities of all OS-UQs with the native complex I, here we present a new assay system using SMPs, which were fused with liposomes incorporating OS-UQ and supplemented with a parasitic quinol oxidase to recycle reduced OS-UQ. In this system, all OS-UQs tested were reduced by the native enzyme, and the reduction was coupled with proton translocation. This finding does not support the canonical tunnel model. We propose that the UQ reaction cavity is flexibly open in the native enzyme to allow OS-UQs to access the reaction site, but their access is obstructed in the isolated enzyme as the cavity is altered by detergent-solubilizing from the mitochondrial membrane.

Lactate oxidation is linked to energy conservation and to oxygen detoxification via a putative terminal cytochrome oxidase in Methanosarcina acetivorans

The marine archaeon Methanosarcina acetivorans contains a putative NAD + -independent d-lactate dehydrogenase (D-iLDH/glycolate oxidase) encoded by the MA4631 gene, belonging to the FAD-oxidase C superfamily. Nucleotide sequences similar to MA4631 gene, were identified in other methanogens and Firmicutes with >90 and 35–40% identity, respectively. Therefore, the lactate metabolism in M. acetivorans is reported here. Cells subjected to intermittent pulses of oxygen (air-adapted; AA-Ma cells) consumed lactate only in combination with acetate, increasing methane production and biomass yield. In AA-Ma cells incubated with d-lactate plus [14C]-l-lactate, the radioactive label was found in methane, CO2 and glycogen, indicating that lactate metabolism fed both methanogenesis and gluconeogenesis. Moreover, d-lactate oxidation was coupled to O2-consumption which was sensitive to HQNO; also, AA-Ma cells showed high transcript levels of gene dld and those encoding subunits A (MA1006) and B (MA1007) of a putative cytochrome bd quinol oxidase, compared to anaerobic control cells. An E. coli mutant deficient in dld complemented with the MA4631 gene, grew with d-lactate as carbon source and showed membrane-bound d-lactate:quinone oxidoreductase activity. The product of the MA4631 gene is a FAD-containing monomer showing activity of iLDH with preference to d-lactate. The results suggested that air adapted M. acetivorans is able to co-metabolize lactate and acetate with associated oxygen consumption by triggering the transcription and synthesis of the D-iLDH and a putative cytochrome bd: methanophenazine (quinol) oxidoreductase. Biomass generation and O2 consumption, suggest a potentially new oxygen detoxification mechanism coupled to energy conservation in this methanogen.

A 2.2 Å cryoEM structure of a quinol-dependent NO Reductase shows close similarity to respiratory oxidases

Quinol-dependent nitric oxide reductases (qNORs) are considered members of the respiratory heme-copper oxidase superfamily, are unique to bacteria, and are commonly found in pathogenic bacteria where they play a role in combating the host immune response. qNORs are also essential enzymes in the denitrification pathway, catalysing the reduction of nitric oxide to nitrous oxide. Here, we determine a 2.2 Å cryoEM structure of qNOR from Alcaligenes xylosoxidans, an opportunistic pathogen and a denitrifying bacterium of importance in the nitrogen cycle. This high-resolution structure provides insight into electron, substrate, and proton pathways, and provides evidence that the quinol binding site not only contains the conserved His and Asp residues but also possesses a critical Arg (Arg720) observed in cytochrome bo3, a respiratory quinol oxidase.

L-tyrosine modulates biofilm formation of Bacillus cereus ATCC 14579

Bacillus cereus is a food-borne pathogen capable of producing biofilms. Following analysis of biofilm formation by B. cereus ATCC 14579 transposon mutants in defined medium (DM), a deletion mutant of bc2939 (Δbc2939) was constructed that showed decreased crystal violet biofilm staining and biofilm cell counts. In addition, Δbc2939 also produced smaller colony biofilms with lower cell counts and loss of wrinkly morphology. The bc2939 gene encodes for Prephenate dehydrogenase, which converts Prephenate to 4-Hydroxy-phenylpyruvate (4-HPPA) in the l-tyrosine branch of the Shikimate pathway. While growth of the mutant and WT in DM was similar, addition of l-tyrosine was required to restore WT-like (colony) biofilm formation. Comparative proteomics showed reduced expression of Tyrosine-protein kinase/phosphatase regulators and extracellular polysaccharide cluster 1 (EPS1) proteins, aerobic electron transfer chain cytochrome aa3/d quinol oxidases, and iso-chorismate synthase involved in menaquinone synthesis in DM grown mutant biofilm cells, while multiple oxidative stress-related catalases and superoxide dismutases were upregulated. Performance in shaking cultures showed a 100-fold lower concentration of menaquinone-7 and reduction in cell counts of DM grown Δbc2939 indicating increased oxygen sensitivity. Combining all results, points to an important role of Tyrosine-modulated EPS1 production and menaquinone-dependent aerobic respiration in B. cereus ATCC 14579 (colony) biofilm formation.

Identification of 2-Aryl-Quinolone Inhibitors of Cytochrome bd and Chemical Validation of Combination Strategies for Respiratory Inhibitors against Mycobacterium tuberculosis.

Mycobacterium tuberculosis cytochrome bd quinol oxidase (cyt bd), the alternative terminal oxidase of the respiratory chain, has been identified as playing a key role during chronic infection and presents a putative target for the development of novel antitubercular agents. Here, we report confirmation of successful heterologous expression of M. tuberculosis cytochrome bd. The heterologous M. tuberculosis cytochrome bd expression system was used to identify a chemical series of inhibitors based on the 2-aryl-quinolone pharmacophore. Cytochrome bd inhibitors displayed modest efficacy in M. tuberculosis growth suppression assays together with a bacteriostatic phenotype in time-kill curve assays. Significantly, however, inhibitor combinations containing our front-runner cyt bd inhibitor CK-2-63 with either cyt bcc-aa3 inhibitors (e.g., Q203) and/or adenosine triphosphate (ATP) synthase inhibitors (e.g., bedaquiline) displayed enhanced efficacy with respect to the reduction of mycobacterium oxygen consumption, growth suppression, and in vitro sterilization kinetics. In vivo combinations of Q203 and CK-2-63 resulted in a modest lowering of lung burden compared to treatment with Q203 alone. The reduced efficacy in the in vivo experiments compared to in vitro experiments was shown to be a result of high plasma protein binding and a low unbound drug exposure at the target site. While further development is required to improve the tractability of cyt bd inhibitors for clinical evaluation, these data support the approach of using small-molecule inhibitors to target multiple components of the branched respiratory chain of M. tuberculosis as a combination strategy to improve therapeutic and pharmacokinetic/pharmacodynamic (PK/PD) indices related to efficacy.

Separation and analysis of Bacillus subtilis respiratory chain complexes.

Bacillus subtilis is a Gram-positive bacterium with a respiratory chain embedded in the cytoplasmic membrane. The respiratory chain is bifurcated after menaquinol into a cytochrome b6c + caa3 branch and a branch with up to three quinol oxidases. The complexes that generate the proton gradient are b6c, associated with caa3 and aa3 oxidase. The b6c and caa3 complexes form a supercomplex, and it is proposed to form respiratory strings in the membrane. There is still information missing about the quinol branch and if the primary oxidase quinol aa3 is associated with the electron donor complexes. It is unclear whether succinate quinone reductase (SQR) can form associations with the quinol branch or the cytochrome branch. In this paper, we show the separation of an almost pure b6c complex associated with cytochromes c550 and c551. We obtained a b6c + caa3 supercomplex of 600kDa and SQR, aa3, and NADH dehydrogenase by dodecyl maltoside solubilization and separation of the respiratory chain components by ionic exchange chromatography. We found that aa3 does not associate with other complexes. SQR was associated with the b6c complex in a mutant lacking aa3. This association could facilitate electron transfer from SQR to menaquinone-7. The lack of associations between the abundant quinol oxidase aa3 and other complexes is a feature we cannot explain yet.

Uropathogenic Escherichia coli subverts mitochondrial metabolism to enable intracellular bacterial pathogenesis in urinary tract infection.

Urinary tract infections are among the most common human bacterial infections and place a significant burden on healthcare systems due to associated morbidity, cost and antibiotic use. Despite being a facultative anaerobe, uropathogenic Escherichia coli, the primary cause of urinary tract infections, requires aerobic respiration to establish infection in the bladder. Here, by combining bacterial genetics with cell culture and murine models of infection, we demonstrate that the widely conserved respiratory quinol oxidase cytochrome bd is required for intracellular infection of urothelial cells. Through a series of genetic, biochemical and functional assays, we show that intracellular oxygen scavenging by cytochrome bd alters mitochondrial physiology by reducing the efficiency of mitochondrial respiration, stabilizing the hypoxia-inducible transcription factor HIF-1 and promoting a shift towards aerobic glycolysis. This bacterially induced rewiring of host metabolism antagonizes apoptosis, thereby protecting intracellular bacteria from urothelial cell exfoliation and preserving their replicative niche. These results reveal the metabolic basis for intracellular bacterial pathogenesis during urinary tract infection and identify subversion of mitochondrial metabolism as a bacterial strategy to facilitate persistence within the urinary tract.

Quinol oxidases in the superfamily of heme-copper oxidoreductases and the cryoEM structure of the cytochrome bo3 ubiquinol oxidase from E. coli

Quinol oxidases in the superfamily of heme-copper oxidoreductases and the cryoEM structure of the cytochrome bo3 ubiquinol oxidase from E. coli