Cytochrome bd confers nitric oxide resistance to Escherichia coli

Mason, Maria G.; Shepherd, Mark; Nicholls, Peter; Dobbin, Paul S.; Dodsworth, Kathryn S; Poole, Robert K.; Cooper, Chris E.

doi:10.1038/nchembio.135

Cited by 152 publications

(183 citation statements)

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“…Nitric oxide and reactive oxygen species are compounds released by macrophages to kill engulfed bacteria (20,21), and cytochrome bd oxidases have been shown to be less sensitive than other cytochrome oxidases to many such compounds (18,20). Consistent with cytochrome bd oxidase being important for bacterial survival within macrophages, cytochrome bd oxidase genes in Brucella suis, the cause of brucellosis, were shown to be induced upon macrophage engulfment, and were required for bacterial survival in the macrophage phagosomes (22).…”

mentioning

confidence: 81%

“…Cytochrome bd oxidases have a number of characterized functions in bacterial cells, including maintaining electron transport during low-oxygen conditions (50), acting as electron donors for the disulfide bond regulatory system (51), providing protection for oxygen-labile proteins (52), and acting as a cyanide-and nitrous oxide-resistant oxidase used by pathogenic bacteria to survive the host immune response (18,20). In addition, these oxidases have multiple catalytic sites that accept a number of different endogenous and artificial substrates (16).…”

Section: Discussionmentioning

confidence: 99%

“…E. coli cells that lack the cytochrome bd-I oxidase genes cydA and/or cydB show a number of cell growth and stress resistance phenotypes (20,(29)(30)(31). To test whether CydX is required for cytochrome bd-I oxidase activity, a ⌬cydX mutant was assayed for phenotypes observed for the cydA and cydB mutants.…”

Section: E Coli Mutants Lacking Cydx Exhibit Phenotypes Associatedmentioning

confidence: 99%

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The Escherichia coli CydX Protein Is a Member of the CydAB Cytochrome bd Oxidase Complex and Is Required for Cytochrome bd Oxidase Activity

et al. 2013

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bCytochrome bd oxidase operons from more than 50 species of bacteria contain a short gene encoding a small protein that ranges from ϳ30 to 50 amino acids and is predicted to localize to the cell membrane. Although cytochrome bd oxidases have been studied for more than 70 years, little is known about the role of this small protein, denoted CydX, in oxidase activity. Here we report that Escherichia coli mutants lacking CydX exhibit phenotypes associated with reduced oxidase activity. In addition, cell membrane extracts from ⌬cydX mutant strains have reduced oxidase activity in vitro. Consistent with data showing that CydX is required for cytochrome bd oxidase activity, copurification experiments indicate that CydX interacts with the CydAB cytochrome bd oxidase complex. Together, these data support the hypothesis that CydX is a subunit of the CydAB cytochrome bd oxidase complex that is required for complex activity. The results of mutation analysis of CydX suggest that few individual amino acids in the small protein are essential for function, at least in the context of protein overexpression. In addition, the results of analysis of the paralogous small transmembrane protein AppX show that the two proteins could have some overlapping functionality in the cell and that both have the potential to interact with the CydAB complex.

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confidence: 81%

Section: Discussionmentioning

confidence: 99%

Section: E Coli Mutants Lacking Cydx Exhibit Phenotypes Associatedmentioning

confidence: 99%

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The Escherichia coli CydX Protein Is a Member of the CydAB Cytochrome bd Oxidase Complex and Is Required for Cytochrome bd Oxidase Activity

et al. 2013

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“…A recent study demonstrated that E. coli cytochrome bd oxidase is involved in resistance to nitric oxide because of its high kinetic offrate (31). Because nitric oxide generated during the oxidative activation of INH by the M. tuberculosis catalase can inhibit bacterial respiratory enzymes (32), impaired cytochrome bd oxidase function might account for the enhanced INH-mediated killing of the cydC:: Tn mutant.…”

Section: Discussionmentioning

confidence: 99%

Mycobacterium tuberculosis persistence mutants identified by screening in isoniazid-treated mice

Dhar

McKinney

2010

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

114

106

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Tuberculosis (TB) is notoriously difficult to cure, requiring administration of multiple antibiotics for 6 mo or longer. Conventional anti-TB drugs inhibit biosynthetic processes involved in cell growth and division, such as DNA replication, RNA transcription, protein translation, and cell wall biogenesis. Although highly effective against bacteria cultured in vitro under optimal growth conditions, these antibiotics are less effective against bacteria grown in vivo in the tissues of a mammalian host. The factors that contribute to the antibiotic tolerance of bacteria grown in vivo are unknown, although altered metabolism and sluggish growth are hypothesized to play a role. To address this question, we identified mutations in Mycobacterium tuberculosis that impaired or enhanced persistence in mice treated with isoniazid (INH), a front-line anti-TB drug. Disruption of cydC, encoding a putative ATP-binding cassette transporter subunit, accelerated bacterial clearance in INH-treated mice without affecting growth or survival in untreated mice. Conversely, transposon insertions within the rv0096-rv0101 gene cluster attenuated bacterial growth and survival in untreated mice but paradoxically prevented INH-mediated killing of bacteria in treated mice. These contrasting phenotypes were dependent on the interaction of the bacteria with the tissue environment because both mutants responded normally to INH when grown in macrophages ex vivo or in axenic cultures in vitro. Our findings have important implications because persistence-impairing mutations would be missed by conventional genetic screens to identify candidate drug targets. Conversely, persistenceenhancing mutations would be missed by standard diagnostic methods, which are performed on bacteria grown in vitro, to detect drug resistance.chemotherapy | drug tolerance | host environment T uberculosis (TB) has been a treatable disease for more than half a century, yet TB eradication remains a distant and possibly unachievable goal barring the introduction of more effective control strategies (1). A formidable obstacle to successful treatment of TB is the requirement for frequent administration of multiple drugs for 6 mo or longer (2). Unless drug administration is closely supervised, the majority of patients will not adhere to such a protracted therapeutical regimen (2). Consequently, patient nonadherence is responsible for high rates of treatment failure, relapse, and emergent drug resistance (3). To reduce treatment costs and improve patient adherence, there is an urgent need for more effective anti-TB drugs to shorten the treatment time (2, 4).Conventional anti-TB drugs target biosynthetic processes involved in cell growth, including RNA transcription [rifampicin (RIF)], protein translation (streptomycin), and cell wall biogenesis [isoniazid (INH)]. Although these drugs rapidly kill Mycobacterium tuberculosis grown in vitro, they are less active against bacteria grown in vivo in mammalian hosts (4,5). In the mouse model of TB, infection progresses through a brief ac...

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“…A time course analysis, however, revealed an impaired killing of E. coli by Cybb Ϫ/Ϫ Nos2 Ϫ/Ϫ M within the first 2 h after infection, which was no longer detectable at later time points (data not shown). Considering that the PHOX-dependent respiratory burst reaches its maximum within 30 min of stimulation (19,80) and that E. coli exhibits various mechanisms of resistance to ROI and RNI (10,50,51,64), it appears obvious that the ultimate control of E. coli by M is PHOX and NOS2 independent. Also, as the exposure to hypoxia was only started at 2 h after infection in our experimental setting (see Fig.…”

Section: Discussionmentioning

confidence: 99%

Hypoxia-Mediated Impairment of the Mitochondrial Respiratory Chain Inhibits the Bactericidal Activity of Macrophages

et al. 2012

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eIn infected tissues oxygen tensions are low. As innate immune cells have to operate under these conditions, we analyzed the ability of macrophages (M) to kill Escherichia coli or Staphylococcus aureus in a hypoxic microenvironment. Oxygen restriction did not promote intracellular bacterial growth but did impair the bactericidal activity of the host cells against both pathogens. This correlated with a decreased production of reactive oxygen intermediates (ROI) and reactive nitrogen intermediates. Experiments with phagocyte NADPH oxidase (PHOX) and inducible NO synthase (NOS2) double-deficient M revealed that in E. colior S. aureus-infected cells the reduced antibacterial activity during hypoxia was either entirely or partially independent of the diminished PHOX and NOS2 activity. Hypoxia impaired the mitochondrial activity of infected M. Inhibition of the mitochondrial respiratory chain activity during normoxia (using rotenone or antimycin A) completely or partially mimicked the defective antibacterial activity observed in hypoxic E. coli-or S. aureus-infected wild-type M, respectively. Accordingly, inhibition of the respiratory chain of S. aureus-infected, normoxic PHOX ؊/؊ NOS2 ؊/؊ M further raised the bacterial burden of the cells, which reached the level measured in hypoxic PHOX ؊/؊ NOS2 ؊/؊ M cultures. Our data demonstrate that the reduced killing of S. aureus or E. coli during hypoxia is not simply due to a lack of PHOX and NOS2 activity but partially or completely results from an impaired mitochondrial antibacterial effector function. Since pharmacological inhibition of the respiratory chain raised the generation of ROI but nevertheless phenocopied the effect of hypoxia, ROI can be excluded as the mechanism underlying the antimicrobial activity of mitochondria.

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Cytochrome bd confers nitric oxide resistance to Escherichia coli

Cited by 152 publications

References 24 publications

The Escherichia coli CydX Protein Is a Member of the CydAB Cytochrome bd Oxidase Complex and Is Required for Cytochrome bd Oxidase Activity

The Escherichia coli CydX Protein Is a Member of the CydAB Cytochrome bd Oxidase Complex and Is Required for Cytochrome bd Oxidase Activity

Mycobacterium tuberculosis persistence mutants identified by screening in isoniazid-treated mice

Hypoxia-Mediated Impairment of the Mitochondrial Respiratory Chain Inhibits the Bactericidal Activity of Macrophages

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