Trimethylamine oxide reduction by Salmonella

1974 ◽  
Vol 20 (12) ◽  
pp. 1745-1748 ◽  
Author(s):  
Kyung Eun Kim ◽  
George W. Chang
Keyword(s):  
Nitrate Reductase ◽  
Mutant Strain ◽  
Anaerobic Growth ◽  
Oxide Reduction ◽  
Trimethylamine Oxide ◽  
Fish Spoilage ◽  
Common Components

Trimethylamine oxide (TMAO) allows the anaerobic growth of Salmonella on glycerol and is thereby reduced to trimethylamine, a volatile indicator of fish spoilage. A mutant strain, TA1530, is unable to reduce either TMAO or nitrate; this suggests that the TMAO and nitrate reductase systems have common components.

scholarly journals Membrane-Bound Nitrate Reductase Is Required for Anaerobic Growth in Cystic Fibrosis Sputum

2007 ◽  
Vol 189 (12) ◽  
pp. 4449-4455 ◽  
Author(s):  
Kelli L. Palmer ◽  
Stacie A. Brown ◽  
Marvin Whiteley
Keyword(s):  
Cystic Fibrosis ◽  
Nitrate Reductase ◽  
Mutational Analysis ◽  
Autosomal Recessive Disorder ◽  
Opportunistic Pathogen ◽  
Anaerobic Growth ◽  
Expression Of Genes ◽  
Membrane Bound ◽  
Lung Infections

ABSTRACT The autosomal recessive disorder cystic fibrosis (CF) affects approximately 70,000 people worldwide and is characterized by chronic bacterial lung infections with the opportunistic pathogen Pseudomonas aeruginosa. To form a chronic CF lung infection, P. aeruginosa must grow and proliferate within the CF lung, and the highly viscous sputum within the CF lung provides a likely growth substrate. Recent evidence indicates that anaerobic microenvironments may be present in the CF lung sputum layer. Since anaerobic growth significantly enhances P. aeruginosa biofilm formation and antibiotic resistance, it is important to examine P. aeruginosa physiology and metabolism in anaerobic environments. Measurement of nitrate levels revealed that CF sputum contains sufficient nitrate to support significant P. aeruginosa growth anaerobically, and mutational analysis revealed that the membrane-bound nitrate reductase is essential for P. aeruginosa anaerobic growth in an in vitro CF sputum medium. In addition, expression of genes coding for the membrane-bound nitrate reductase complex is responsive to CF sputum nitrate levels. These findings suggest that the membrane-bound nitrate reductase is critical for P. aeruginosa anaerobic growth with nitrate in the CF lung.

scholarly journals Compensatory periplasmic nitrate reductase activity supports anaerobic growth ofPseudomonas aeruginosaPAO1 in the absence of membrane nitrate reductase

2009 ◽  
Vol 55 (10) ◽  
pp. 1133-1144 ◽  
Author(s):  
Nadine E. Van Alst ◽  
Lani A. Sherrill ◽  
Barbara H. Iglewski ◽  
Constantine G. Haidaris
Keyword(s):  
Nitrate Reductase ◽  
Response Regulator ◽  
Reductase Activity ◽  
Transcriptional Start Site ◽  
Atp Synthesis ◽  
Anaerobic Growth ◽  
Start Site ◽  
Terminal Electron Acceptor ◽  
Periplasmic Nitrate Reductase ◽  
Growth Recovery

Nitrate serves as a terminal electron acceptor under anaerobic conditions in Pseudomonas aeruginosa . Reduction of nitrate to nitrite generates a transmembrane proton motive force allowing ATP synthesis and anaerobic growth. The inner membrane-bound nitrate reductase NarGHI is encoded within the narK1K2GHJI operon, and the periplasmic nitrate reductase NapAB is encoded within the napEFDABC operon. The roles of the 2 dissimilatory nitrate reductases in anaerobic growth, and the regulation of their expressions, were examined by use of a set of deletion mutants in P. aeruginosa PAO1. NarGHI mutants were unable to grow anaerobically, but plate cultures remained viable up to 120 h. In contrast, the nitrate sensor-response regulator mutant ΔnarXL displayed growth arrest initially, but resumed growth after 72 h and reached the early stationary phase in liquid culture after 120 h. Genetic, transcriptional, and biochemical studies demonstrated that anaerobic growth recovery by the NarXL mutant was the result of NapAB periplasmic nitrate reductase expression. A novel transcriptional start site for napEFDABC expression was identified in the NarXL mutant grown anaerobically. Furthermore, mutagenesis of a consensus NarL-binding site monomer upstream of the novel transcriptional start site restored anaerobic growth recovery in the NarXL mutant. The data suggest that during anaerobic growth of wild-type P. aeruginosa PAO1, the nitrate response regulator NarL directly represses expression of periplasmic nitrate reductase, while inducing maximal expression of membrane nitrate reductase.

Bacteria Decomposing Amino Acids in Bulk-Stored Capelin (Mallotus villosus)

1983 ◽  
Vol 40 (12) ◽  
pp. 2092-2097 ◽  
Author(s):  
J. Kjosbakken ◽  
I. Storrø ◽  
H. Larsen
Keyword(s):  
Amino Acids ◽  
Viable Count ◽  
Anaerobic Growth ◽  
Mallotus Villosus ◽  
Trimethylamine Oxide ◽  
Obligate Anaerobic ◽  
Spoilage Bacteria ◽  
The Family ◽  
Capelin Mallotus Villosus ◽  
Hydrophobic Amino Acids

Bacteria that decompose amino acids were isolated from anaerobically stored capelin (Mallotus villosus) depleted of trimethylamine oxide (TMAO). Some of the 19 isolated strains could be assigned to Lactobacillus, or Bacteroidaceae, but others were not easily identified. Bacteria of the family Bacteroidaceae dominated the anaerobic viable count in the capelin mass in a period after the total reduction of TMAO. Most of the isolated strains differed from each other by decomposing different sets of the free amino acids, or decomposing amino acids at different rates during anaerobic growth in capelin extracts. Most strains isolated from the fish at the later stages of storage, and notably the Bacteroidaceae, produced copious amounts of NH3. Hydrophilic amino acids were the main source of the NH3 produced. Hydrophobic amino acids and other nonprotein nitrogenous components of the capelin extract were not decomposed by any of the 19 organisms, with the exception of the quantitatively less significant hypoxanthine, which was decomposed by three of the strains. Members of the family Bacteroidaceae may be prominent spoilage bacteria in fish, having until now escaped attention because of their obligate anaerobic and psychrotrophic nature.

scholarly journals Metabolic Flux Control at the Pyruvate Node in an Anaerobic Escherichia coli Strain with an Active Pyruvate Dehydrogenase

2010 ◽  
Vol 76 (7) ◽  
pp. 2107-2114 ◽  
Author(s):  
Qingzhao Wang ◽  
Mark S. Ou ◽  
Y. Kim ◽  
L. O. Ingram ◽  
K. T. Shanmugam
Keyword(s):  
Escherichia Coli ◽  
Mutant Strain ◽  
Pyruvate Dehydrogenase ◽  
Metabolic Flux ◽  
Anaerobic Growth ◽  
Kinetic Properties ◽  
Fermentation Products ◽  
E Coli ◽  
Pyruvate Node

ABSTRACT During anaerobic growth of Escherichia coli, pyruvate formate-lyase (PFL) and lactate dehydrogenase (LDH) channel pyruvate toward a mixture of fermentation products. We have introduced a third branch at the pyruvate node in a mutant of E. coli with a mutation in pyruvate dehydrogenase (PDH*) that renders the enzyme less sensitive to inhibition by NADH. The key starting enzymes of the three branches at the pyruvate node in such a mutant, PDH*, PFL, and LDH, have different metabolic potentials and kinetic properties. In such a mutant (strain QZ2), pyruvate flux through LDH was about 30%, with the remainder of the flux occurring through PFL, indicating that LDH is a preferred route of pyruvate conversion over PDH*. In a pfl mutant (strain YK167) with both PDH* and LDH activities, flux through PDH* was about 33% of the total, confirming the ability of LDH to outcompete the PDH pathway for pyruvate in vivo. Only in the absence of LDH (strain QZ3) was pyruvate carbon equally distributed between the PDH* and PFL pathways. A pfl mutant with LDH and PDH* activities, as well as a pfl ldh double mutant with PDH* activity, had a surprisingly low cell yield per mole of ATP (Y ATP) (about 7.0 g of cells per mol of ATP) compared to 10.9 g of cells per mol of ATP for the wild type. The lower Y ATP suggests the operation of a futile energy cycle in the absence of PFL in this strain. An understanding of the controls at the pyruvate node during anaerobic growth is expected to provide unique insights into rational metabolic engineering of E. coli and related bacteria for the production of various biobased products at high rates and yields.

A composite biochemical system for bacterial nitrate and nitrite assimilation as exemplified by Paracoccus denitrificans

2011 ◽  
Vol 435 (3) ◽  
pp. 743-753 ◽  
Author(s):  
Andrew J. Gates ◽  
Victor M. Luque-Almagro ◽  
Alan D. Goddard ◽  
Stuart J. Ferguson ◽  
M. Dolores Roldán ◽  
...  
Keyword(s):  
Nitrate Reductase ◽  
Nitrogen Source ◽  
Nitrite Reductase ◽  
Paracoccus Denitrificans ◽  
Gene Clusters ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Nitrite Reduction ◽  
Anaerobic Growth ◽  
Nitrate And Nitrite

The denitrifying bacterium Paracoccus denitrificans can grow aerobically or anaerobically using nitrate or nitrite as the sole nitrogen source. The biochemical pathway responsible is expressed from a gene cluster comprising a nitrate/nitrite transporter (NasA), nitrite transporter (NasH), nitrite reductase (NasB), ferredoxin (NasG) and nitrate reductase (NasC). NasB and NasG are essential for growth with nitrate or nitrite as the nitrogen source. NADH serves as the electron donor for nitrate and nitrite reduction, but only NasB has a NADH-oxidizing domain. Nitrate and nitrite reductase activities show the same Km for NADH and can be separated by anion-exchange chromatography, but only fractions containing NasB retain the ability to oxidize NADH. This implies that NasG mediates electron flux from the NADH-oxidizing site in NasB to the sites of nitrate and nitrite reduction in NasC and NasB respectively. Delivery of extracellular nitrate to NasBGC is mediated by NasA, but both NasA and NasH contribute to nitrite uptake. The roles of NasA and NasC can be substituted during anaerobic growth by the biochemically distinct membrane-bound respiratory nitrate reductase (Nar), demonstrating functional overlap. nasG is highly conserved in nitrate/nitrite assimilation gene clusters, which is consistent with a key role for the NasG ferredoxin, as part of a phylogenetically widespread composite nitrate and nitrite reductase system.

scholarly journals The mechanism of proton translocation driven by the respiratory nitrate reductase complex of Escherichia coli

1980 ◽  
Vol 190 (1) ◽  
pp. 79-94 ◽  
Author(s):  
Robert W. Jones ◽  
Alan Lamont ◽  
Peter B. Garland
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Mutant Strain ◽  
Cytoplasmic Membrane ◽  
Reductase Activity ◽  
Proton Translocation ◽  
Deficient Mutant ◽  
Benzyl Viologen ◽  
Low Concentrations ◽  
Nitrite Reductase Activity

Low concentrations (1–50μm) of ubiquinol1 were rapidly oxidized by spheroplasts of Escherichia coli derepressed for synthesis of nitrate reductase using either nitrate or oxygen as electron acceptor. Oxidation of ubiquinol1 drove an outward translocation of protons with a corrected →H+/2e− stoichiometry [Scholes & Mitchell (1970) J. Bioenerg.1, 309–323] of 1.49 when nitrate was the acceptor and 2.28 when oxygen was the acceptor. Proton translocation driven by the oxidation of added ubiquinol1 was also observed in spheroplasts from a double quinone-deficient mutant strain AN384 (ubiA−menA−), whereas a haem-deficient mutant, strain A1004a, did not oxidize ubiquinol1. Proton translocation was not observed if either the protonophore carbonyl cyanide m-chlorophenylhydrazone or the respiratory inhibitor 2-n-heptyl-4-hydroxyquinoline N-oxide was present. When spheroplasts oxidized Diquat radical (DQ+) to the oxidized species (DQ++) with nitrate as acceptor, nitrate was reduced to nitrite according to the reaction: [Formula: see text] and nitrite was further reduced in the reaction: [Formula: see text] Nitrite reductase activity (2) was inhibited by CO, leaving nitrate reductase activity (1) unaffected. Benzyl Viologen radical (BV+) is able to cross the cytoplasmic membrane and is oxidized directly by nitrate reductase to the divalent cation, BV++. In the presence of CO, this reaction consumes two protons: [Formula: see text] The consumption of these protons could not be detected by a pH electrode in the extra-cellular bulk phase of a suspension of spheroplasts unless the cytoplasmic membrane was made permeable to protons by the addition of nigericin or tetrachlorosalicylanilide. It is concluded that the protons of eqn. (3) are consumed at the cytoplasmic aspect of the cytoplasmic membrane. Diquat radical, reduced N-methylphenazonium methosulphate and its sulphonated analogue N-methylphenazonium-3-sulphonate (PMSH) and ubiquinol1 are all oxidized by nitrate reductase via a haem-dependent, endogenous quinone-independent, 2-n-heptyl-4-hydroxyquinoline N-oxide-sensitive pathway. Approximate→H+/2e− stoichiometries were zero with Diquat radical, an electron donor, 1.0 with reduced N-methylphenazonium methosulphate or its sulphonated analogue, both hydride donors, and 2.0 with ubiquinol1 (QH2), a hydrogen donor. It is concluded that the protons appearing in the medium are derived from the reductant and the observed→H+/2e− stoichiometries are accounted for by the following reactions occurring at the periplasmic aspect of the cytoplasmic membrane.: [Formula: see text]

scholarly journals Resolution of Distinct Membrane-Bound Enzymes from Enterobacter cloacae SLD1a-1 That Are Responsible for Selective Reduction of Nitrate and Selenate Oxyanions

2006 ◽  
Vol 72 (8) ◽  
pp. 5173-5180 ◽  
Author(s):  
Helen Ridley ◽  
Carys A. Watts ◽  
David J. Richardson ◽  
Clive S. Butler
Keyword(s):  
Nitrate Reductase ◽  
Reductase Activity ◽  
Selective Reduction ◽  
Enterobacter Cloacae ◽  
Anaerobic Growth ◽  
Elemental Selenium ◽  
Membrane Bound ◽  
Membrane Bound Enzymes ◽  
Distinct Membrane

ABSTRACT Enterobacter cloacae SLD1a-1 is capable of reductive detoxification of selenate to elemental selenium under aerobic growth conditions. The initial reductive step is the two-electron reduction of selenate to selenite and is catalyzed by a molybdenum-dependent enzyme demonstrated previously to be located in the cytoplasmic membrane, with its active site facing the periplasmic compartment (C. A. Watts, H. Ridley, K. L. Condie, J. T. Leaver, D. J. Richardson, and C. S. Butler, FEMS Microbiol. Lett. 228:273-279, 2003). This study describes the purification of two distinct membrane-bound enzymes that reduce either nitrate or selenate oxyanions. The nitrate reductase is typical of the NAR-type family, with α and β subunits of 140 kDa and 58 kDa, respectively. It is expressed predominantly under anaerobic conditions in the presence of nitrate, and while it readily reduces chlorate, it displays no selenate reductase activity in vitro. The selenate reductase is expressed under aerobic conditions and expressed poorly during anaerobic growth on nitrate. The enzyme is a heterotrimeric (αβγ) complex with an apparent molecular mass of ∼600 kDa. The individual subunit sizes are ∼100 kDa (α), ∼55 kDa (β), and ∼36 kDa (γ), with a predicted overall subunit composition of α3β3γ3. The selenate reductase contains molybdenum, heme, and nonheme iron as prosthetic constituents. Electronic absorption spectroscopy reveals the presence of a b-type cytochrome in the active complex. The apparent Km for selenate was determined to be ∼2 mM, with an observed V max of 500 nmol SeO4 2− min−1 mg−1 (k cat, ∼5.0 s−1). The enzyme also displays activity towards chlorate and bromate but has no nitrate reductase activity. These studies report the first purification and characterization of a membrane-bound selenate reductase.

scholarly journals Regulation of Expression of theyiaKLMNOPQRS Operon for Carbohydrate Utilization inEscherichia coli: Involvement of the Main Transcriptional Factors

2000 ◽  
Vol 182 (16) ◽  
pp. 4617-4624 ◽  
Author(s):  
Ester Ibañez ◽  
Evangelina Campos ◽  
Laura Baldoma ◽  
Juan Aguilar ◽  
Josefa Badia
Keyword(s):  
Mutant Strain ◽  
Integration Host Factor ◽  
Anaerobic Growth ◽  
Receptor Protein ◽  
Mobility Shift ◽  
Regulation Of Expression ◽  
Carbohydrate Utilization ◽  
In The Wild ◽  
Gel Mobility Shift ◽  
Transcriptional Fusions

ABSTRACT The yiaKLMNOPQRS (yiaK-S) gene cluster ofEscherichia coli is believed to be involved in the utilization of a hitherto unknown carbohydrate which generates the intermediate l-xylulose. Transcription ofyiaK-S as a single message from the unique promoter found upstream of yiaK is proven in this study. The 5′ end has been located at 60 bp upstream from the ATG. Expression of theyiaK-S operon is controlled in the wild-type strain by a repressor encoded by yiaJ. No inducer molecule of theyiaK-S operon has been identified among over 80 carbohydrate or derivative compounds tested, the system being expressed only in a mutant strain lacking the YiaJ repressor. ThelacZ transcriptional fusions in the genetic background of the mutant strain revealed that yiaK-S is modulated by the integration host factor and by the cyclic AMP (cAMP)-cAMP receptor protein (Crp) activator complex. A twofold increase in the induction was observed during anaerobic growth, which was independent of ArcA or Fnr. Gel mobility shift assays showed that the YiaJ repressor binds to a promoter fragment extending from −50 to +121. These studies also showed that the cAMP-Crp complex can bind to two different sites. ThelacZ transcriptional fusions of different fragments of the promoter demonstrated that binding of cAMP-Crp to the Crp site 1, centered at −106, is essential for yiaK-S expression. The 5′ end of the yiaJ gene was determined, and its promoter region was found to overlap with the divergent yiaK-Spromoter. Expression of yiaJ is autogenously regulated and reduced by the binding of Crp-cAMP to the Crp site 1 of theyiaK-S promoter.

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