scholarly journals Transport of C4-Dicarboxylates inWolinella succinogenes

2000 ◽  
Vol 182 (20) ◽  
pp. 5757-5764 ◽  
Author(s):  
Roland Ullmann ◽  
Roland Gross ◽  
Jörg Simon ◽  
Gottfried Unden ◽  
Achim Kröger
Keyword(s):  
Carbon Source ◽  
Cytoplasmic Membrane ◽  
Anaerobic Respiration ◽  
Molar Ratio ◽  
Nitrate Respiration ◽  
Gene Products ◽  
Dicarboxylate Transport ◽  
Proton Potential ◽  
Fumarate Respiration ◽  
Cytoplasmic Side

ABSTRACT C4-dicarboxylate transport is a prerequisite for anaerobic respiration with fumarate in Wolinella succinogenes, since the substrate site of fumarate reductase is oriented towards the cytoplasmic side of the membrane. W. succinogenes was found to transport C4-dicarboxylates (fumarate, succinate, malate, and aspartate) across the cytoplasmic membrane by antiport and uniport mechanisms. The electrogenic uniport resulted in dicarboxylate accumulation driven by anaerobic respiration. The molar ratio of internal to external dicarboxylate concentration was up to 103. The dicarboxylate antiport was either electrogenic or electroneutral. The electroneutral antiport required the presence of internal Na+, whereas the electrogenic antiport also operated in the absence of Na+. In the absence of Na+, no electrochemical proton potential (Δp) was measured across the membrane of cells catalyzing fumarate respiration. This suggests that the proton potential generated by fumarate respiration is dissipated by the concomitant electrogenic dicarboxylate antiport. Three gene loci (dcuA,dcuB, and dctPQM) encoding putative C4-dicarboxylate transporters were identified on the genome of W. succinogenes. The predicted gene products ofdcuA and dcuB are similar to the Dcu transporters that are involved in the fumarate respiration ofEscherichia coli with external C4-dicarboxylates. The genes dctP, -Q, and -M probably encode a binding-protein-dependent secondary uptake transporter for dicarboxylates. A mutant (DcuA− DcuB−) ofW. succinogenes lacking the intact dcuA anddcuB genes grew by nitrate respiration with succinate as the carbon source but did not grow by fumarate respiration with fumarate, malate, or aspartate as substrates. The DcuA−, DcuB−, and DctQM− mutants grew by fumarate respiration as well as by nitrate respiration with succinate as the carbon source. Cells of the DcuA− DcuB−mutant performed fumarate respiration without generating a proton potential even in the presence of Na+. This explains why the DcuA− DcuB− mutant does not grow by fumarate respiration. Growth by fumarate respiration appears to depend on the function of the Na+-dependent, electroneutral dicarboxylate antiport which is catalyzed exclusively by the Dcu transporters. Dicarboxylate transport via the electrogenic uniport is probably catalyzed by the DctPQM transporter and by a fourth, unknown transporter that may also operate as an electrogenic antiporter.

The contribution of nitrate respiration to the energy budget of the symbiont-containing clam Lucinoma aequizonata: a calorimetric study

1996 ◽  
Vol 199 (2) ◽  
pp. 427-433
Author(s):  
U Hentschel ◽  
S Hand ◽  
H Felbeck
Keyword(s):  
Heat Production ◽  
Sea Water ◽  
Anaerobic Respiration ◽  
Gill Tissue ◽  
Nitrate Respiration ◽  
Heat Output ◽  
Marine Bivalve ◽  
Calorimetric Study ◽  
Perfusion Medium ◽  
Terminal Electron Acceptor

Heat production and nitrate respiration rates were measured simultaneously in the gill tissue of Lucinoma aequizonata. This marine bivalve contains chemoautotrophic, intracellular, bacterial symbionts in its gill tissue. The symbionts show constitutive anaerobic respiration, using nitrate instead of oxygen as a terminal electron acceptor. An immediate increase in heat production was observed after the addition of nitrate to the perfusion medium of the calorimeter and this was accompanied by the appearance of nitrite in the effluent sea water. The nitrate-stimulated heat output was similar under aerobic and anaerobic conditions, which is consistent with the constitutive nature of nitrate respiration. The amount of heat released was dependent on the concentration of nitrate in the perfusion medium. At nitrate concentrations between 0.5 and 5 mmol l-1, the total heat production was increased over twofold relative to unstimulated baseline values. A mean (±s.e.m.) experimental enthalpy of -130±22.6 kJ mol-1 nitrite (N=13) was measured for this concentration range.

scholarly journals Mycobacterium tuberculosis Is Able To Accumulate and Utilize Cholesterol

2009 ◽  
Vol 191 (21) ◽  
pp. 6584-6591 ◽  
Author(s):  
Anna Brzostek ◽  
Jakub Pawelczyk ◽  
Anna Rumijowska-Galewicz ◽  
Bozena Dziadek ◽  
Jaroslaw Dziadek
Keyword(s):  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Carbon Source ◽  
Sole Carbon Source ◽  
Cytoplasmic Membrane ◽  
Degradation Pathway ◽  
Cholesterol Accumulation ◽  
Targeted Disruption ◽  
Future Studies

ABSTRACT It is expected that the obligatory human pathogen Mycobacterium tuberculosis must adapt metabolically to the various nutrients available during its cycle of infection, persistence, and reactivation. Cholesterol, which is an important part of the mammalian cytoplasmic membrane, is a potential energy source. Here, we show that M. tuberculosis grown in medium containing a carbon source other than cholesterol is able to accumulate cholesterol in the free-lipid zone of its cell wall. This cholesterol accumulation decreases the permeability of the cell wall for the primary antituberculosis drug, rifampin, and partially masks the mycobacterial surface antigens. Furthermore, M. tuberculosis was able to grow on mineral medium supplemented with cholesterol as the sole carbon source. Targeted disruption of the Rv3537 (kstD) gene inhibited growth due to inactivation of the cholesterol degradation pathway, as evidenced by accumulation of the intermediate, 9-hydroxy-4-androstene-3,17-dione. Our findings that M. tuberculosis is able to accumulate cholesterol in the presence of alternative nutrients and use it when cholesterol is the sole carbon source in vitro may facilitate future studies into the pathophysiology of this important deadly pathogen.

scholarly journals Preparation of β-Cyclodextrin Inclusion Complex and Its Application as an Intumescent Flame Retardant for Epoxy

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 71 ◽  
Author(s):  
Xueying Shan ◽  
Kuanyu Jiang ◽  
Jinchun Li ◽  
Yan Song ◽  
Ji Han ◽  
...  
Keyword(s):  
Carbon Source ◽  
Inclusion Complex ◽  
Flame Retardant ◽  
1H Nmr ◽  
Intumescent Flame Retardant ◽  
Molar Ratio ◽  
Gravimetric Analysis ◽  
X Ray ◽  
Cone Calorimeter Test ◽  
The Impact

A new P-N containing the flame retardant, which was namely N,N′-dibutyl-phosphate diamide (DBPDA), was synthesized and it was assembled into the cavity of β-cyclodextrin (β-CD) to form an inclusion complex (IC). The structure and properties of IC were characterized by Fourier transform infraredspectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), 1H nuclear magnetic resonance (1H NMR), scanning electron microscopy with X-ray microanalysis (SEM-EDS), differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA). 1H NMR and SEM-EDS were also used to identify the molar ratio of β-CD/DBPDA in IC and the results from the analyses indicated that their molar ratio was 1:1. In order to test the flame retardant effect of IC, it was added to epoxy (EP). IC was proposed to be able to act as an intumescent flame retardant (IFR) system in EP through a combination of β-CD and DBPDA properties during the combustion process. β-CD is a biomass carbon source, which has the advantages of environmental protection and low cost. Furthermore, DBPDA is both a source of acid and gas. When IC was heated, IC had the advantage of acting as both a carbon source and foam forming agent, while the DBPDA component were able to directly generate phosphoric acid and NH3 in situ. The impact of IC in low additive amounts on flame retardancy of EP was studied by the cone calorimeter test. When only 3 wt % IC was incorporated, the peak values of heat release rate (pHRR) and smoke production rate (pSPR) of EP were reduced by 22.9% and 33.3% respectively, which suggested that IC could suppress the heat and smoke release efficiently.

scholarly journals Studies on the Mode of Action of Reutericyclin

2003 ◽  
Vol 69 (2) ◽  
pp. 1305-1307 ◽  
Author(s):  
Michael G. Gänzle ◽  
Rudi F. Vogel
Keyword(s):  
Mode Of Action ◽  
Cytoplasmic Membrane ◽  
Fluorescent Dyes ◽  
Large Molecules ◽  
Proton Potential

ABSTRACT The mode of action of reutericyclin was determined with fluorescent dyes that probed the permeability of the cytoplasmic membrane by large molecules, protons, and potassium. A comparison of reutericyclin activity with those of nisin, nigericin, and valinomycin demonstrated that reutericyclin does not form pores but selectively dissipates the transmembrane proton potential.

scholarly journals A Na+-coupled C4-dicarboxylate transporter (Asuc_0304) and aerobic growth of Actinobacillus succinogenes on C4-dicarboxylates

Microbiology ◽  
2014 ◽  
Vol 160 (7) ◽  
pp. 1533-1544 ◽  
Author(s):  
Mi Na Rhie ◽  
Hyo Eun Yoon ◽  
Hye Yun Oh ◽  
Sandra Zedler ◽  
Gottfried Unden ◽  
...  
Keyword(s):  
Sequence Similarity ◽  
Major Product ◽  
Anaerobic Growth ◽  
Actinobacillus Succinogenes ◽  
Aerobic Growth ◽  
Succinate Production ◽  
E Coli ◽  
Dicarboxylate Transport ◽  
Transporter Family ◽  
Proton Potential

Actinobacillus succinogenes, which is known to produce large amounts of succinate during fermentation of hexoses, was able to grow on C4-dicarboxylates such as fumarate under aerobic and anaerobic conditions. Anaerobic growth on fumarate was stimulated by glycerol and the major product was succinate, indicating the involvement of fumarate respiration similar to succinate production from glucose. The aerobic growth on C4-dicarboxylates and the transport proteins involved were studied. Fumarate was oxidized to acetate. The genome of A. succinogenes encodes six proteins with similarity to secondary C4-dicarboxylate transporters, including transporters of the Dcu (C4-dicarboxylate uptake), DcuC (C4-dicarboxylate uptake C), DASS (divalent anion : sodium symporter) and TDT (tellurite resistance dicarboxylate transporter) family. From the cloned genes, Asuc_0304 of the DASS family protein was able to restore aerobic growth on C4-dicarboxylates in a C4-dicarboxylate-transport-negative Escherichia coli strain. The strain regained succinate or fumarate uptake, which was dependent on the electrochemical proton potential and the presence of Na+. The transport had an optimum pH ~7, indicating transport of the dianionic C4-dicarboxylates. Transport competition experiments suggested substrate specificity for fumarate and succinate. The transport characteristics for C4-dicarboxylate uptake by cells of aerobically grown A. succinogenes were similar to those of Asuc_0304 expressed in E. coli, suggesting that Asuc_0304 has an important role in aerobic fumarate uptake in A. succinogenes. Asuc_0304 has sequence similarity to bacterial Na+-dicarboxylate cotransporters and contains the carboxylate-binding signature. Asuc_0304 was named SdcA (sodium-coupled C4-dicarboxylate transporter from A . succinogenes).

scholarly journals Succinate dehydrogenase functioning by a reverse redox loop mechanism and fumarate reductase in sulphate-reducing bacteria

Microbiology ◽  
2006 ◽  
Vol 152 (8) ◽  
pp. 2443-2453 ◽  
Author(s):  
Tanja Zaunmüller ◽  
David J. Kelly ◽  
Frank O. Glöckner ◽  
Gottfried Unden
Keyword(s):  
Succinate Dehydrogenase ◽  
Draft Genome ◽  
Desulfovibrio Desulfuricans ◽  
Geobacter Sulfurreducens ◽  
Fumarate Reductase ◽  
Desulfovibrio Vulgaris ◽  
Succinate Oxidation ◽  
Proton Potential ◽  
Fumarate Respiration ◽  
Reducing Bacteria

Sulphate- or sulphur-reducing bacteria with known or draft genome sequences (Desulfovibrio vulgaris, Desulfovibrio desulfuricans G20, Desulfobacterium autotrophicum [draft], Desulfotalea psychrophila and Geobacter sulfurreducens) all contain sdhCAB or frdCAB gene clusters encoding succinate : quinone oxidoreductases. frdD or sdhD genes are missing. The presence and function of succinate dehydrogenase versus fumarate reductase was studied. Desulfovibrio desulfuricans (strain Essex 6) grew by fumarate respiration or by fumarate disproportionation, and contained fumarate reductase activity. Desulfovibrio vulgaris lacked fumarate respiration and contained succinate dehydrogenase activity. Succinate oxidation by the menaquinone analogue 2,3-dimethyl-1,4-naphthoquinone depended on a proton potential, and the activity was lost after degradation of the proton potential. The membrane anchor SdhC contains four conserved His residues which are known as the ligands for two haem B residues. The properties are very similar to succinate dehydrogenase of the Gram-positive (menaquinone-containing) Bacillus subtilis, which uses a reverse redox loop mechanism in succinate : menaquinone reduction. It is concluded that succinate dehydrogenases from menaquinone-containing bacteria generally require a proton potential to drive the endergonic succinate oxidation. Sequence comparison shows that the SdhC subunit of this type lacks a Glu residue in transmembrane helix IV, which is part of the uncoupling E-pathway in most non-electrogenic FrdABC enzymes.

scholarly journals Nitrogen and Oxygen Regulation of Bacillus subtilis nasDEF Encoding NADH-Dependent Nitrite Reductase by TnrA and ResDE

1998 ◽  
Vol 180 (20) ◽  
pp. 5344-5350 ◽  
Author(s):  
Michiko M. Nakano ◽  
Tamara Hoffmann ◽  
Yi Zhu ◽  
Dieter Jahn
Keyword(s):  
Bacillus Subtilis ◽  
Nitrate Reductase ◽  
Nitrite Reductase ◽  
Nitrogen Limitation ◽  
Reductase Activity ◽  
Anaerobic Respiration ◽  
Regulatory System ◽  
Nitrate Respiration ◽  
Nitrite Reductase Activity ◽  
Nitrate And Nitrite

ABSTRACT The nitrate and nitrite reductases of Bacillus subtilishave two different physiological functions. Under conditions of nitrogen limitation, these enzymes catalyze the reduction of nitrate via nitrite to ammonia for the anabolic incorporation of nitrogen into biomolecules. They also function catabolically in anaerobic respiration, which involves the use of nitrate and nitrite as terminal electron acceptors. Two distinct nitrate reductases, encoded bynarGHI and nasBC, function in anabolic and catabolic nitrogen metabolism, respectively. However, as reported herein, a single NADH-dependent, soluble nitrite reductase encoded by the nasDE genes is required for both catabolic and anabolic processes. The nasDE genes, together with nasBC(encoding assimilatory nitrate reductase) and nasF(required for nitrite reductase siroheme cofactor formation), constitute the nas operon. Data presented show that transcription of nasDEF is driven not only by the previously characterized nas operon promoter but also from an internal promoter residing between the nasC andnasD genes. Transcription from both promoters is activated by nitrogen limitation during aerobic growth by the nitrogen regulator, TnrA. However, under conditions of oxygen limitation,nasDEF expression and nitrite reductase activity were significantly induced. Anaerobic induction of nasDEFrequired the ResDE two-component regulatory system and the presence of nitrite, indicating partial coregulation of NasDEF with the respiratory nitrate reductase NarGHI during nitrate respiration.

scholarly journals Staphylococcus aureusCoproporphyrinogen III Oxidase Is Required for Aerobic and Anaerobic Heme Synthesis

mSphere ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Jacob E. Choby ◽  
Eric P. Skaar
Keyword(s):  
Staphylococcus Aureus ◽  
Anaerobic Respiration ◽  
Model Organism ◽  
Anaerobic Growth ◽  
Cellular Respiration ◽  
Nitrate Respiration ◽  
Human Pathogen ◽  
Content Type ◽  
Heme Synthesis ◽  
Aerobic And Anaerobic

ABSTRACTThe virulence of the human pathogenStaphylococcus aureusis supported by many heme-dependent proteins, including key enzymes of cellular respiration. Therefore, synthesis of heme is a critical component of staphylococcal physiology.S. aureusgenerates heme via the coproporphyrin-dependent pathway, conserved across members of theFirmicutesandActinobacteria. In this work, we genetically investigate the oxidation of coproporphyrinogen to coproporphyrin in this heme synthesis pathway. The coproporphyrinogen III oxidase CgoX has previously been identified as the oxygen-dependent enzyme responsible for this conversion under aerobic conditions. However, becauseS. aureususes heme during anaerobic nitrate respiration, we hypothesized that coproporphyrin production is able to proceed in the absence of oxygen. Therefore, we tested the contribution to anaerobic heme synthesis of CgoX and two other proteins previously identified as potential oxygen-independent coproporphyrinogen dehydrogenases, NWMN_1486 and NWMN_1636. We have found that CgoX alone is responsible for aerobic and anaerobic coproporphyrin synthesis from coproporphyrinogen and is required for aerobic and anaerobic heme-dependent growth. This work provides an explanation for howS. aureusheme synthesis proceeds under both aerobic and anaerobic conditions.IMPORTANCEHeme is a critical molecule required for aerobic and anaerobic respiration by organisms across kingdoms. The human pathogenStaphylococcus aureushas served as a model organism for the study of heme synthesis and heme-dependent physiology and, like many species of the phylaFirmicutesandActinobacteria, generates heme through a coproporphyrin intermediate. A critical step in terminal heme synthesis is the production of coproporphyrin by the CgoX enzyme, which was presumed to be oxygen dependent. However,S. aureusalso requires heme during anaerobic growth; therefore, the synthesis of coproporphyrin by an oxygen-independent mechanism is required. Here, we identify CgoX as the enzyme performing the oxygen-dependent and -independent synthesis of coproporphyrin from coproporphyrinogen, resolving a key outstanding question in the coproporphyrin-dependent heme synthesis pathway.

scholarly journals The conserved 3′ UTR-derived small RNA NarS mediates mRNA crossregulation during nitrate respiration

2019 ◽  
Vol 48 (4) ◽  
pp. 2126-2143 ◽  
Author(s):  
Chuan Wang ◽  
Yanjie Chao ◽  
Gianluca Matera ◽  
Qian Gao ◽  
Jörg Vogel
Keyword(s):  
Transcriptional Control ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Anaerobic Respiration ◽  
Nitrate Respiration ◽  
Rnase E ◽  
Small Noncoding Rnas ◽  
Nitrite Toxicity ◽  
Nitrate And Nitrite ◽  
Bacterial Cytoplasm

Abstract Small noncoding RNAs (sRNAs) from mRNA 3′ UTRs seem to present a previously unrecognized layer of bacterial post-transcriptional control whereby mRNAs influence each other's expression, independently of transcriptional control. Studies in Escherichia coli and Salmonella enterica showed that such sRNAs are natural products of RNase E-mediated mRNA decay and associate with major RNA-binding proteins (RBPs) such as Hfq and ProQ. If so, there must be additional sRNAs from mRNAs that accumulate only under specific physiological conditions. We test this prediction by characterizing candidate NarS that represents the 3′ UTR of nitrate transporter NarK whose gene is silent during standard aerobic growth. We find that NarS acts by Hfq-dependent base pairing to repress the synthesis of the nitrite transporter, NirC, resulting in mRNA cross-regulation of nitrate and nitrite transporter genes. Interestingly, the NarS-mediated repression selectively targets the nirC cistron of the long nirBDC-cysG operon, an observation that we rationalize as a mechanism to protect the bacterial cytoplasm from excessive nitrite toxicity during anaerobic respiration with abundant nitrate. Our successful functional assignment of a 3′ UTR sRNA from a non-standard growth condition supports the notion that mRNA crossregulation is more pervasive than currently appreciated.

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