Phenazine ethosulfate as a preferred electron acceptor to phenazine methosulfate in dye-linked enzyme assays.
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Coloring Agents↗
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Results for “Phenazines”
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Phenazine-1,6-dicarboxylate as the common precursor of other bacterial phenazines [proceedings].
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Carbon Radioisotopes↗
Cloning and heterologous expression of the phenazine biosynthetic locus from Pseudomonas aureofaciens 30-84.
Pseudomonas aureofaciens strain 30-84 suppresses take-all disease of wheat caused by Gaeumannomyces graminis var. tritici. Three antibiotics, phenazine-1-carboxylic acid, 2-hydroxyphenazine-1-carboxylic acid, and 2-hydroxyphenazine, were responsible for disease suppression. Tn5-induced mutants deficient in production of one or more of the antibiotics (Phz-) were significantly less suppressive than the parental strain. Cosmids pLSP259 and pLSP282 from a genomic library of strain 30-84 restored phenazine production and fungal inhibition to 10 different Phz- mutants. Sequences required for production of the phenazines were localized to a segment of approximately 2.8 kilobases that was present in both cosmids. Expression of this locus in Escherichia coli required the introduction of a functional promoter, was orientation-specific, and resulted in the production of all three phenazine antibiotics. These results strongly suggest that the cloned sequences encode a major portion of the phenazine biosynthetic pathway.
Antifungal Agents↗
Biosynthesis of phenazine pigments in mutant and wild-type cultures of Pseudomonas aeruginosa.
Pigmentation mutants of Pseudomonas aeruginosa, selected by observed visual differences in coloration from the wild-type strain, were examined for altered patterns of phenazine synthesis. Three classes of mutants that were incapable of pyocyanine production were identified. Pigmentation patterns that were found to characterize the various mutant classes implicated precursor-product relationships, and a biochemical scheme covering the terminal reactions of pyocyanine biosynthesis is proposed. Among compounds tested as inhibitors of pigmentation, two effectively inhibited pyocyanine production production while allowing cell growth. p-Aminobenzoate inhibited total pigmentation; i.e., no other phenazine accumulated. m-Aminobenzoate inhibited a presumptive methylation step in pyocyanine biosynthesis, abolishing the formation of pyocyanine and aeruginosin pigments but increasing the yields of phenazine 1-carboxylic acid and oxychlororaphin. D-[2,3,4,5(n)-14C]shikimate was most efficiently incorporated into phenazines in the middle to late exponential phase of growth. Label was incorporated predominantly into pyocyanine in the absence of inhibitors and into phenazine 1-carboxylic acid when the organism was grown in the presence of m-aminobenzoate.
4-Aminobenzoic Acid↗
Pseudomonas aeruginosa phenazines dictate site-specific competitive interactions with Klebsiella pneumoniae.
Pseudomonas aeruginosa and Klebsiella pneumoniae are Gram-negative opportunistic pathogens that frequently colonize the human body and are major causes of infection. These bacteria are often co-isolated in polymicrobial urinary tract and lung infections, the latter of which is associated with increased disease severity and worse clinical outcomes. Despite their overlapping niches and clinical relevance, little is known about how these two pathogens interact and how those interactions influence human health. Given the growing recognition that microbial interactions are key drivers of disease, we investigated how P. aeruginosa and K. pneumoniae influence one another. We discovered an antagonistic interaction in which P. aeruginosa restricts the growth of K. pneumoniae. This inhibition is driven by phenazine production in P. aeruginosa, specifically the secondary metabolites pyocyanin and pyorubin, which are both necessary and sufficient to suppress K. pneumoniae growth. Using a diverse set of clinical isolates, we found that this antagonism is strain dependent. Both the susceptibility of K. pneumoniae to phenazines and the ability of P. aeruginosa to restrict K. pneumoniae growth varies between strains. Moreover, the necessity of phenazine production is specific to the site of infection. Together, these findings demonstrate that strain background and environmental context are critical determinants of pathogen interactions. Our work underscores the importance of considering these variables when investigating how microbial interactions influence infection and disease outcomes.
Journal Article↗
Leukotriene B4 omega-oxidation by human polymorphonuclear leukocytes is inhibited by pyocyanin, a phenazine derivative produced by Pseudomonas aeruginosa.
Human polymorphonuclear leukocytes (PMNL) metabolize the potent chemotaxin leukotriene B4 (LTB4) by omega-oxidation to 20-hydroxyl-LTB4 and 20-carboxy-LTB4. The ability of unstimulated human PMNL to metabolize exogenous LTB4 was found to be inhibited by pyocyanin, a phenazine derivative produced by Pseudomonas aeruginosa, in a dose-dependent manner. 1-Hydroxyphenazine (1-OHP), a metabolite of pyocyanin, was not inhibitory under identical conditions. The initial enzymic step in the conversion of LTB4 is catalyzed by an NADPH-dependent cytochrome, P-450. Reduction of the phenazine derivatives by NADPH was measured spectrophotometrically. Pyocyanin was reduced by NADPH in vitro in a pH-dependent manner, while 1-OHP was poorly or negligibly reduced under similar conditions. Formation of NADP+ was 20.3 +/- 1.8 nmol min-1 for pyocyanin (10 microM) at pH 5.5, compared with 0.6 +/- 0.2 nmol min-1 for 1-OHP (10 microM), while at pH 7.5 a value of 2.2 +/- 1.3 nmol min-1 was obtained for pyocyanin, with no detectable activity for 1-OHP. This indicates that inhibition of LTB4 omega-hydroxylase activity by pyocyanin might be achieved by competition for NADPH. Incorporation of exogenous 5-hydroxyeicosatetraenoic acid by PMNL into lipid pools was not affected by either phenazine derivative. The ability of bacterial pyocyanin to limit the omega-oxidation of LTB4 may have important implications for PMNL LTB4 receptor status and chemotaxis in vivo.
Humans↗
Phenazines with two cationic side chains as potential antimalarials.
1,9-Phenazine-bis(dialkylaminocarboxamides) were prepared for screening as potential antimalarials. No significant activity against Plasmodium berghei was observed. The phenazine targets were prepared from 1,9-phenazinedicarboxylic acid by standard methods. The reaction between 1,9-phenazinedicarboxylic acid and thionyl chloride in the presence of dimethylformamide unexpectedly gave 4-chloro-1,9-phenazinedicarbonyl chloride.
Animals↗
On the subsarcolemmal localization of phenazine ethosulfate-linked alpha-glycerophasphate dehydrogenase activity in pigeon pectoralis white muscle fibres.
In this study frozen sections of avian striated muscles were incubated for mitochondrial alpha-glycerophosphate de hydrognease (alpha=GPD) reaction, and the effect of menadione, phenazine methosulfate (PMS) or phenazine ethosulfate (PES) as intermediate electron acceptors was evaluated. Under histochemical conditions, PMS or PES-linked alpha-GPD reaction was poor in the chicken posterior latissimus dorsi and chicken pectoralis muscles. However, PMS or PES-linked alpha-GPD reaction was present characteristically in the subsarcolemmal mitochondria of the "broad white" fibres of the pigeon pectoralis muscle only; the subsarcolemmal mitochondria of the narrow red fibres lacked such a reaction pattern. The above reaction pattern, however, differed when compared with the menadione-linked alpha-GPD reaction. The present histochemical evidence suggests the existence of an inherent heterogeneity in the mitochondrial populations of the different avian striated muscle fibres studied.
Animals↗
Antitubercular 2,8-bis(alkylaminomethyl)phenazines.
The preparation and antitubercular properties of a series of 2,8-bis(alkylaminomethyl)phenazines are described. These compounds all inhibited the growth of Mycobacterium smegmatis ATCC 607 in vitro. 2,8-Bis(dibutylaminomethyl)phenazine (5c) was also active against a lethal Mycobacterium tuberculosis H37Rv infection in mice.
Animals↗
The inhibitory effect of the artificial electron donor system, phenazine methosulfate-ascorbate, on bacterial transport mechanisms.
The artificial electron donor system, phenazine methosulfate (PMS)-ascorbate, inhibited active transort of solutes in Pseudomonas aeruginosa irrespective of whether the active transport systems were shock sensitive or shock resistant. N,N,N',N'-tetramethylphenylenediamine could be substituted for PMS but a higher concentration was required. PMS-ascorbate also inhibited active transport in several other bacterial species with the exception of Escherichia coli and of a nonpigmented strain of Serratia marcescens. PMS-ascorbate previously has been shown to energize active transport in isolated membrane vesicles, even those prepared from the same bacterial species in whose intact cells active transport was inhibited. The apparent Km of glucose active transport in untreated cells of P. aeruginosa was 40 micron while the Km of glucose transport in cells incubated with PMS-ascorbate was 25 mM, and PMS-ascorbate had no effect on efflux of accumulated glucose. These results strongly suggested that facilitated diffusion resulted upon exposure of the cells to PMS- ascorbate. Thus, PMS-ascorbate appeared to have an uncoupler-like effect on cells of P. aeruginosa. The experimental data also pointed out that there are fundamental differences between the response of intact cells and membrane vesicles to exogenous electron donors.
Ascorbic Acid↗
Studies on the reduction of nitroblue tetrazolium chloride mediated through the action of NADH and phenazine methosulphate.
The general features of the reduction of nitroblue tetrazolium chloride (NBT) by NADH and phenazine methosulphate (PMS) have been studied under aerobic and anaerobic conditions. Under aerobic condition the reduction appears to be mediated through the intermediate formation of the superoxide anion radical O2-.; this reaction is strongly inhibited by superoxide dismutase and by a number of O2-. scavengers such as propyl gallate, (+)-catechin, manganous ions, reduced glutathione and benzoquinone. Cupric ions inhibited the overall reaction by reoxidising reduced PMS. Under anaerobic conditions, superoxide dismutase had only a small inhibitory action and, with the exception of cupric ions, the other substances mentioned above were ineffective as inhibitors. The data presented show that the use of NBT to detect the presence of O2-. is fraught with difficulties due to an equally rapid reduction of NBT by NADH and PMS under anaerobic conditions.
Free Radicals↗
A phenazine analogue of actinomycin D.
An analogue of actinomycin D (1), in which the phenoxazone chromophore has been replaced by a phenazine, has been synthesized and characterized. Although this compound (2) lacks the 2-amino group and does not possess the quinoid structure of 1, it does bind to DNA, but less tightly than either 1 or the 2-deamino derivative of 1. NMR and CD spectra indicate that the peptide conformations in 2 are approximately as in 1; there was no apparent asymmetry of the two peptide rings. Compound 2 inhibited nucleic acid synthesis in L1210 cell cultures more effectively than does 2-deaminoactinomycin D, but about one-tenth as well as does actinomycin D.
Animals↗
Hydroxylation of aromatic compounds by reduced nicotinamide-adenine dinucleotide and phenazine methosulphate requires hydrogen peroxide and hydroxyl radicals, but not superoxide.
1. A mixture of NADH and phenazine methosulphate hydroxylates aromatic compounds at acidic pH values. 2. Hydroxylation is inhibited by catalase and by scavengers of the hydroxyl radical (-OH) but not by superoxide dismutase. 3. It is concluded that neither O2 leads to nor HO2- is sufficiently reactive to hydroxylate aromatic rings.
Hydrogen Peroxide↗
4,9-Dihydroxyphenazine-1,6-dicarboxylic acid dimethylester and the 'missing link' in phenazine biosynthesis.
4,9-Dihydroxyphenazine-1,6-dicarboxylic acid dimethylester, the ester form of a proposed 'missing link' in the biosynthesis of phenazines, has been isolated from a strain of Pseudomonas cepacia.
Mass Spectrometry↗
Pattern of phenazine pigment production by a strain of Pseudomonas aeruginosa.
An atypical strain of Pseudomonas aeruginosa capable of synthesizing three phenazine pigments was isolated. Cultural conditions, under which the strain forms either chlororaphin, oxychlororaphin, or pyocyanine, are described. This broad spectrum of pigment production, as well as some other characteristics, sets this strain apart from previously described chlororaphin producers.
Ammonia↗
The effect of phenazine methosulfate-ascorbate on bacterial active transport and adenosine triphosphate formation: inhibition of Pseudomonas aeruginosa and stimulation of Escherichia coli.
The artificial electron-donor system, phenazine methosulfate (PMS) ascorbate, inhibited active transport of glucose by Pseudomonas aeruginosa irrespective of whether the incubation systems were in air, flushed with oxygen, or gassed with nitrogen under anaerobic denitrifying conditions. Active transport of glucose by P. aeruginosa was also inhibited by reduced 5-N-methyl-phenazonium-3-sulfonate, a membrane-impermeable electron donor. PMS-ascorbate caused rapid depletion of intracellular adenosine triphosphate (ATP) when added to respiring cell suspensions of P. aeruginosa either in the presence or absence of glucose or succinate as oxidizable energy sources. In contrast, under identical conditions, Escherichia coli formed ATP with PMS-ascorbate as the sole oxidizable energy source and ATP formation continued when glucose or succinate was present in addition to PMS-ascorbate in the incubation system.
Adenosine Triphosphate↗
Stimulation of rat lung metabolism with 2,4-dinitrophenol and phenazine methosulfate.
Glucose metabolism was stimulated in isolated perfused rat lungs by perfusion with 2,4-dinitrophenol (DNP), an uncoupler of oxidative phosphorylation or phenazine methosulfate (PMS), an artificial hydrogen acceptor. Lungs were ventilated with 95% O2:5% CO2 and perfused with Krebs-Ringer bicarbonate buffer pH 7.4 containing 5.5 mM [U-14C, 5-3H]glucose for 100 min. In control lungs, 45% of total glucose 14C was recovered as perfusate lactate plus pyruvate (L+P) and 24% as 14CO2. Perfuson with 0.8 mM DNP resulted in a 102% increase in 14CO2 production and a 98% increase in L+P, associated with a fall in tissue ATP/ADP ratio and decreased incorporation of glucose carbons into lipids. Perfusion with 8 muM PMS resulted in a 116% increase in 14CO2 production but no change in L+P; the lactate-to-pyruvate ratio in the perfusate was reduced to 4 from a control value of 10, and tissue adenine nucleotide levels were unchanged. In all experiments, 3H was mainly recovered as 3H2O in the perfusate. These data demonstrate the pattern of response of the isolated lung preparation to uncoupling of oxidative phosphorylation and to alterations in cytoplasmic redox state. The results suggest that the isolated lung preparation is metabolically intact and suitable for study of metabolic control processes.
Adenine Nucleotides↗
Lactate-dehydrogenase activity in the rat testis: a comparison between fluorometric assay of freeze-dried sections and histochemical localization with phenazine methosulphate.
The activity of lactate dehydrogenase (LDH) in freeze-dried sections of rat testes was determined by using a fluorometric assay method and found to be 4.47 +/- 0.23 moles/Kg dry weight/hr (MKDH +/- S.E.M.) in whole sections, 3.31 +/- 0.16 in tubules and 12.0 +/- 1.9 in interstitial tissue. The activities and regional variation are similar to those measured in nervous tissue and are well correlated with the histochemical localization of LDH activity when phenazine methosulphate (PMS) is not used as an electron carrier. LDH and lipoamide dehydrogenase activity have the same histochemical distribution and there is no nonspecific staining with either method. The use of PMS results in reduced dependence on substrate and coenzyme and does not indicate higher interstitial activity but may provide an indication of developing lactate metabolism in maturing sperm. It is recomended that methods with and without PMS be used in studies of LDH activity in the testis.
Animals↗