The oxidation of nicotinic acid by Pseudomonas ovalis Chester. The terminal oxidase.
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ABSTRACT:
SUBMITTER: Jones MV
PROVIDER: S-EPMC1174177 | biostudies-other | 1972 Sep
REPOSITORIES: biostudies-other
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Project description:Soil bacteria are generally capable of growth on a wide range of organic chemicals, and pseudomonads are particularly adept at utilizing aromatic compounds. Pseudomonads are motile bacteria that are capable of sensing a wide range of chemicals, using both energy taxis and chemotaxis. Whilst the identification of specific chemicals detected by the ?26 chemoreceptors encoded in Pseudomonas genomes is ongoing, the functions of only a limited number of Pseudomonas chemoreceptors have been revealed to date. We report here that McpC, a methyl-accepting chemotaxis protein in Pseudomonas putida F1 that was previously shown to function as a receptor for cytosine, was also responsible for the chemotactic response to the carboxylated pyridine nicotinic acid.
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Project description:Background:5-Hydroxymethylfurfural (HMF) is a highly valuable platform chemical that can be obtained from plant biomass carbohydrates. HMF can be oxidized to 2,5-furandicarboxylic acid (FDCA), which is used as a renewable substitute for the petroleum-based terephthalic acid in polymer production. Results:Aryl-alcohol oxidase (AAO) from the white-rot fungus Pleurotus eryngii is able to oxidize HMF and its derivative 2,5-diformylfuran (DFF) producing formylfurancarboxylic acid (FFCA) thanks to its activity on benzylic alcohols and hydrated aldehydes. Here, we report the ability of AAO to produce FDCA from FFCA, opening up the possibility of full oxidation of HMF by this model enzyme. During HMF reactions, an inhibitory effect of the H2O2 produced in the first two oxidation steps was found to be the cause of the lack of AAO activity on FFCA. In situ monitoring of the whole reaction by 1H-NMR confirmed the absence of any unstable dead-end products, undetected in the HPLC analyses, that could be responsible for the incomplete conversion. The deleterious effect of H2O2 was confirmed by successful HMF conversion into FDCA when the AAO reaction was carried out in the presence of catalase. On the other hand, no H2O2 formation was detected during the slow FFCA conversion by AAO in the absence of catalase, in contrast to typical oxidase reaction with HMF and DFF, suggesting an alternative mechanism as reported in some reactions of related flavo-oxidases. Moreover, several active-site AAO variants that yield nearly complete conversion in shorter reaction times than the wild-type enzyme have been identified. Conclusions:The use of catalase to remove H2O2 from the reaction mixture leads to 99% conversion of HMF into FDCA by AAO and several improved variants, although the mechanism of peroxide inhibition of the AAO action on the aldehyde group of FFCA is not fully understood.
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Project description:Stopped-flow kinetics were made of the reaction between ascorbate-reduced Pseudomonas cytochrome oxidase and potassium ferricyanide under both N2 and CO atmospheres. Under N2 three kinetic processes were observed, two being dependent on ferricyanide concentration, with second-order rate constants of 9.6 X 10(4)M-1.s-1 and 1.5 X 10(4)M-1.s-1, whereas the other was concentration-independent, with a first-order rate constant of 0.17 +/- 0.03s-1. Measurements of their kinetic difference spectra have allowed the fastest and second-fastest phases of the reaction to be assigned to direct bimolecular reactions of ferricyanide with the haem c and haem d, moieties of the enzyme respectively. Under CO, the second-order rate constant for the reaction of the haem c was, at 1.3 X 10(5)M-1.s-1, slightly enhanced over the rate in a N2 atmosphere, but the reaction velocity of the haem d1 component was greatly decreased, being apparently limited to that of the rates of CO dissociation from the molecule (0.15s-1 and 0.03s-1). The results are compared with those obtained during a previous study of the reaction of reduced Pseudomonas cytochrome oxidase with oxidized azurin.
| S-EPMC1185823 | biostudies-other
Project description:The schizophrenia-related protein G72 plays a unique role in the regulation of D-amino acid oxidase (DAO) in great apes. Several psychiatric diseases, including schizophrenia and bipolar disorder, are linked to overexpression of DAO and G72. Whether G72 plays a positive or negative regulatory role in DAO activity, however, has been controversial. Exploring the molecular basis of the relationship between G72 and DAO is thus important to understand how G72 regulates DAO activity. We performed yeast two-hybrid experiments and determined enzymatic activity to identify potential sites in G72 involved in binding DAO. Our results demonstrate that residues 123-153 and 138-153 in the long isoform of G72 bind to DAO and enhance its activity by 22% and 32%, respectively. A docking exercise indicated that these G72 peptides can interact with loops in DAO that abut the entrance of the tunnel that substrate and cofactor must traverse to reach the active site. We propose that a unique gating mechanism underlies the ability of G72 to increase the activity of DAO. Because upregulation of DAO activity decreases d-serine levels, which may lead to psychiatric abnormalities, our results suggest a molecular mechanism involving interaction between DAO and the C-terminal region of G72 that can regulate N-methyl-d-aspartate receptor-mediated neurotransmission.
| S-EPMC3907796 | biostudies-literature
Project description:Pseudomonas aeruginosa, an opportunistic pathogen of humans, uses quorum sensing (QS) to regulate the production of extracellular products that can benefit all members of the population. P. aeruginosa can police QS-deficient cheaters by producing hydrogen cyanide, which is also QS regulated; however, the mechanism by which cooperators selectively protect themselves from the toxicity of cyanide remained unresolved. Here, we show that a cyanide-insensitive terminal oxidase encoded by cioAB provides resistance to cyanide, but only in QS-proficient strains. QS-deficient cheaters do not activate cioAB transcription. QS-mediated regulation of cioAB expression depends on production of both cyanide by cooperators (which is QS regulated) and reactive oxygen species (ROS) from cheaters (which is not QS regulated). This type of regulatory system allows cooperating populations to respond, via ROS, to the presence of cheaters, and might allow them to defer the substantial metabolic cost of policing until cheaters are present in the population.
| S-EPMC6825135 | biostudies-literature
Project description:Pseudomonas putida GB-1-002 catalyzes the oxidation of Mn2+. Nucleotide sequence analysis of the transposon insertion site of a nonoxidizing mutant revealed a gene (designated cumA) encoding a protein homologous to multicopper oxidases. Addition of Cu2+ increased the Mn2+-oxidizing activity of the P. putida wild type by a factor of approximately 5. The growth rates of the wild type and the mutant were not affected by added Cu2+. A second open reading frame (designated cumB) is located downstream from cumA. Both cumA and cumB probably are part of a single operon. The translation product of cumB was homologous (level of identity, 45%) to that of orf74 of Bradyrhizobium japonicum. A mutation in orf74 resulted in an extended lag phase and lower cell densities. Similar growth-related observations were made for the cumA mutant, suggesting that the cumA mutation may have a polar effect on cumB. This was confirmed by site-specific gene replacement in cumB. The cumB mutation did not affect the Mn2+-oxidizing ability of the organism but resulted in decreased growth. In summary, our data indicate that the multicopper oxidase CumA is involved in the oxidation of Mn2+ and that CumB is required for optimal growth of P. putida GB-1-002.
| S-EPMC91248 | biostudies-literature
Project description:1. The l-malate dehydrogenase of Pseudomonas ovalis Chester, which is independent of nicotinamide nucleotides and which is structurally and functionally bound to the cell-wall membrane, has been prepared in a soluble form and partially purified. 2. The purified dehydrogenase exhibits a triple cofactor requirement for FAD, quinone and phospholipid, and in the presence of these cofactors can utilize 2,6-dichlorophenol-indophenol as hydrogen acceptor. 3. The formation of reduced forms of FAD was not detected, but in the presence of both FAD and phospholipid the enzyme catalysed the reduction of quinone by l-malate at rates equivalent to those obtained with 2,6-dichlorophenol-indophenol as terminal acceptor. The l-malate dehydrogenase of Ps. ovalis Chester is therefore an l-malate-quinone oxidoreductase. 4. The quinone and the phospholipids present in the fragments of the cell-wall membrane from which the soluble dehydrogenase was prepared have been extracted and purified. The quinone was identified as coenzyme Q(9). At least eight phospholipids were detected, and the major component is an unsaturated phosphatidylethanolamine. 5. The nature of the phospholipid required to activate the enzyme depends on the nature of the quinone used in the assay system. When 2-methyl-1,4-naphthaquinone is used, a wide variety of phospholipids, including all those isolated from the organism, will activate the enzyme, but when coenzyme Q(9) is used the phospholipid specificity of the enzyme is much more restricted, and the most effective activator is the unsaturated phosphatidylethanolamine isolated from the organism. 6. Evidence is presented to support the view that the restricted phospholipid specificity exhibited by the enzyme in the presence of coenzyme Q(9), as opposed to the broad specificity exhibited when 2-methyl-1,4-naphthaquinone is used, is due to the fact that coenzyme Q(9) has a large substituent on position 3.
| S-EPMC1270136 | biostudies-other
Project description:We identified the fatty acid synthesis (FAS) initiation enzyme in Pseudomonas aeruginosa as FabY, a ?-ketoacyl synthase KASI/II domain-containing enzyme that condenses acetyl coenzyme A (acetyl-CoA) with malonyl-acyl carrier protein (ACP) to make the FAS primer ?-acetoacetyl-ACP in the accompanying article (Y. Yuan, M. Sachdeva, J. A. Leeds, and T. C. Meredith, J. Bacteriol. 194:5171-5184, 2012). Herein, we show that growth defects stemming from deletion of fabY can be suppressed by supplementation of the growth media with exogenous decanoate fatty acid, suggesting a compensatory mechanism. Fatty acids eight carbons or longer rescue growth by generating acyl coenzyme A (acyl-CoA) thioester ?-oxidation degradation intermediates that are shunted into FAS downstream of FabY. Using a set of perdeuterated fatty acid feeding experiments, we show that the open reading frame PA3286 in P. aeruginosa PAO1 intercepts C(8)-CoA by condensation with malonyl-ACP to make the FAS intermediate ?-keto decanoyl-ACP. This key intermediate can then be extended to supply all of the cellular fatty acid needs, including both unsaturated and saturated fatty acids, along with the 3-hydroxyl fatty acid acyl groups of lipopolysaccharide. Heterologous PA3286 expression in Escherichia coli likewise established the fatty acid shunt, and characterization of recombinant ?-keto acyl synthase enzyme activity confirmed in vitro substrate specificity for medium-chain-length acyl CoA thioester acceptors. The potential for the PA3286 shunt in P. aeruginosa to curtail the efficacy of inhibitors targeting FabY, an enzyme required for FAS initiation in the absence of exogenous fatty acids, is discussed.
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Project description:In this study, it was shown for the first time that l-amino acid oxidase of Pseudomonas sp. AIU813, renamed as l-amino acid oxidase/monooxygenase (l-AAO/MOG), exhibits l-lysine 2-monooxygenase as well as oxidase activity. l-Lysine oxidase activity of l-AAO/MOG was increased in a p-chloromercuribenzoate (p-CMB) concentration-dependent manner to a final level that was five fold higher than that of the non-treated enzyme. In order to explain the effects of modification by the sulfhydryl reagent, saturation mutagenesis studies were carried out on five cysteine residues, and we succeeded in identifying l-AAO/MOG C254I mutant enzyme, which showed five-times higher specific activity of oxidase activity than that of wild type. The monooxygenase activity shown by the C254I variant was decreased significantly. Moreover, we also determined a high-resolution three-dimensional structure of l-AAO/MOG to provide a structural basis for its biochemical characteristics. The key residue for the activity conversion of l-AAO/MOG, Cys-254, is located near the aromatic cage (Trp-418, Phe-473, and Trp-516). Although the location of Cys-254 indicates that it is not directly involved in the substrate binding, the chemical modification by p-CMB or C254I mutation would have a significant impact on the substrate binding via the side chain of Trp-516. It is suggested that a slight difference of the binding position of a substrate can dictate the activity of this type of enzyme as oxidase or monooxygenase.
| S-EPMC3970082 | biostudies-literature
Project description:All non-H atoms of the title compound, C(7)H(7)NO(2), are nearly coplaner, the r.m.s. deviation being 0.0087?Å. In the crystal, the partially overlapped arrangement and the face-to-face distance of 3.466?(17)?Å between parallel pyridine rings of neighboring mol-ecules indicates the existence of ?-? stacking. Inter-molecular O-H?N hydrogen bonding and weak C-H?O hydrogen bonding are present in the crystal structure.
| S-EPMC3200684 | biostudies-literature