scholarly journals New Substrates for the Dicarboxylate Transport System of Sinorhizobium meliloti

2000 ◽  
Vol 182 (15) ◽  
pp. 4216-4221 ◽  
Author(s):  
Svetlana Yurgel ◽  
Michael W. Mortimer ◽  
Kimberly N. Rogers ◽  
Michael L. Kahn
Keyword(s):  
Dicarboxylic Acid ◽  
Transport System ◽  
Sinorhizobium Meliloti ◽  
Monocarboxylic Acid ◽  
Dicarboxylic Acids ◽  
Carbonyl Groups ◽  
Nitrogen Fixing ◽  
Extended Conformation ◽  
Dicarboxylate Transport ◽  
Succinamic Acid

ABSTRACT The dicarboxylate transport (Dct) system of Sinorhizobium meliloti, which is essential for a functional nitrogen-fixing symbiosis, has been thought to transport only dicarboxylic acids. We show here that the permease component of the Dct system, DctA, can transport orotate, a monocarboxylic acid, with an apparentKm of 1.7 mM and a V maxof 163 nmol min−1 per mg of protein in induced cells. DctA was not induced by the presence of orotate. The transport of orotate was inhibited by several compounds, including succinamic acid and succinamide, which are not dicarboxylic acids. The dicarboxylic acid maleate (cis-butenedioic acid) was not an inhibitor of orotate transport, which suggests that it was not recognized by DctA. However, maleate was an excellent inducer of DctA expression. Our evaluation of 17 compounds as inducers and inhibitors of transport suggests that substrates recognized by S. meliloti DctA must have appropriately spaced carbonyl groups and an extended conformation, while good inducers are more likely to have a curved conformation.

scholarly journals DctBD-Dependent and -Independent Expression of the Sinorhizobium (Rhizobium) meliloti C4-Dicarboxylate Transport Gene (dctA) During Symbiosis

1998 ◽  
Vol 11 (9) ◽  
pp. 878-886 ◽  
Author(s):  
Bert Boesten ◽  
Jacques Batut ◽  
Pierre Boistard
Keyword(s):  
Nitrogen Fixation ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Meliloti ◽  
Dicarboxylic Acids ◽  
Lacz Gene ◽  
Gene Fusions ◽  
Nitrogen Fixing ◽  
Wild Type ◽  
Coding Region ◽  
Dicarboxylate Transport

The Sinorhizobium meliloti C4-dicarboxylate transport gene (dctA) is essential for symbiotic nitrogen fixation. Under free-living conditions, the expression of dctA is fully dependent on the cognate regulatory genes dctBD. However, during symbiosis with the Medicago sativa host plant, the dctA gene is efficiently expressed even in the absence of the dctBD genes. The spatial expression of the dctA gene has been monitored in situ in mature nitrogen-fixing nodules formed by wild-type and dctD mutant strains. In nodules induced by a wild-type strain, expression was observed in both the infection zone and the nitrogen-fixing zone of the nodule. DctD-independent expression of dctA was observed with a previously described dctA∷lacZ fusion (pCU700) and was found to be confined to the fixation zone (zone III) of mature nodules. Therefore, the operation of the alternative system of symbiotic dctA activation (ASA) is concomitant with the onset of nitrogen fixation, which could be consistent with an increased need for transport of (C)4(-dicarboxylic acids by the nitrogen-fixing) bacteroids. Sequences in the 5′ part of the dctA coding region were found to be essential for the activation of the dctA∷lacZ gene fusions by the ASA. Deletion of these sequences resulted in gene fusions that were found to be strictly dependent on dctBD for expression, under all conditions tested including symbiosis. Such gene fusions allowed us to establish that the DctBD-dependent dctA expression was occurring throughout the whole nodule.

scholarly journals Succinate uptake and related proton movements in Escherichia coli K12

1975 ◽  
Vol 152 (3) ◽  
pp. 647-654 ◽  
Author(s):  
S J Gutowski ◽  
H Rosenberg
Keyword(s):  
Escherichia Coli ◽  
Dicarboxylic Acid ◽  
Transport System ◽  
Dicarboxylic Acids ◽  
Acid Transport ◽  
Cationic Form ◽  
Whole Cells ◽  
Escherichia Coli K12 ◽  
Proton Uptake

1. The apparent Km values for succinate uptake by whole cells of Escherichia coli K12 depend on pH in the range 6.5-7.4.2. Uptake of succinate in lightly buffered medium is accompanied by proton uptake. 3. The apparent Km values for succinate uptake and for succinate-induced proton uptake are similar. 4. Approximately two protons enter the cell with each succinate molecule. 5. The pattern of inhibition of succinate uptake is similar to that of succinate-induced proton uptake. 6. Uptake of fumarate and malate, which share the succinate-transport system, is also accompanied by the uptake of approximately two protons per molecule of fumarate or malate. 7. Uptake of aspartate by the dicarboxylic acid-transport system is accompanied by the uptake of approximatley two protons per molecule of asparatate. 8. It is concluded that uptake of dicarboxylic acids by the dicarboxylic acid-transport system is obligatorily coupled to proton uptake such that succinate, malate and fumarate are taken up in electroneutral form and asparate is taken up in cationic form. 9. These results are consistent with, though they do not definitely prove, the energization of succinate uptake of the deltapH.

Dicarboxylic acid transport in Escherichia coli K12: involvement of a binding protein in the translocation of dicarboxylic acids across the outer membrane of the cell envelope

1979 ◽  
Vol 57 (6) ◽  
pp. 653-661 ◽  
Author(s):  
Mary A. Bewick ◽  
Theodore C. Y. Lo
Keyword(s):  
Escherichia Coli ◽  
Cell Surface ◽  
Outer Membrane ◽  
Transport System ◽  
Cell Envelope ◽  
Binding Protein ◽  
Dicarboxylic Acids ◽  
Escherichia Coli K12 ◽  
Dicarboxylate Transport ◽  
Active Transport System

We have previously found that the dicarboxylate transport system in Escherichia coli K12 is an active transport system and that at least one binding protein and two cytoplasmic membrane transport components are involved in the uptake of dicarboxylic acids. Recently, through surface labelling studies, some dicarboxylate binding proteins were found to be exposed on the cell surface. In the present paper, we demonstrate that the dicarboxylate transport component located in the outer membrane can be inactivated by two different kinds of nonpenetrating inhibitors, viz. proteases, and diazosulfanilic acid. These inhibitors seem to act on the dicarboxylate binding protein. By adding this protein to inactivated cells or to transport-negative mutants, we have succeeded in reconstituting the dicarboxylate transport system. These findings suggest that the dicarboxylate binding protein found on the cell surface plays an essential role in the translocation of dicarboxylic acids across the outer membrane.

IR and 13C, 17O, and 119Sn NMR spectra of some bis(1-butyl)tin(IV) carboxylates of dicarboxylic acids

1991 ◽  
Vol 56 (9) ◽  
pp. 1908-1915 ◽  
Author(s):  
Jaroslav Holeček ◽  
Antonín Lyčka ◽  
Milan Nádvorník ◽  
Karel Handlíř
Keyword(s):  
Infrared Spectroscopy ◽  
Nmr Spectroscopy ◽  
Dicarboxylic Acid ◽  
Nmr Spectra ◽  
Dicarboxylic Acids ◽  
119Sn Nmr ◽  
Carboxylic Groups ◽  
Cyclic Oligomers ◽  
The Media ◽  
Oxygen Atoms

Infrared spectroscopy and multinuclear (13C, 17O, and 119Sn NMR spectroscopy have been used to study the structure of bis(1-butyl)tin(IV) carboxylates of dicarboxylic acids (1-C4H9)2. Sn(X(COO)2), where X = (CH2)n (n = 0-8), CH=CH (cis and trans) and C6H4 (ortho and para).The crystalline compounds are formed by linear or cyclic oligomers or polymers whose basic building units represent a grouping composed of the central tin atom substituted by two 1-butyl groups and coordinated with both oxygen atoms of two anisobidentate carboxylic groups derived from different molecules of a dicarboxylic acid. The environment of the tin atom has a shape of a trapezoidal bipyramid. When dissolvet in non-coordinating solvents, the compounds retain the oligomeric character with unchanged structure of environment of the central tin atom. In the media of coordinating solvents the bis(1-butyl)tin(IV) carboxylates of dicarboxylic acids form complexes whose central hexacoordinated tin atom binds two molecules of the solvent trough their donor atoms. Carboxylic groups form monodenate linkages in these complexes.

scholarly journals Genetic Analysis of Mutations Affecting pckA Regulation in Rhizobium (Sinorhizobium) meliloti

Genetics ◽  
1997 ◽  
Vol 147 (4) ◽  
pp. 1521-1531 ◽  
Author(s):  
Magne Østerås ◽  
Shelley A P O'Brien ◽  
Turlough M Finan
Keyword(s):  
Sinorhizobium Meliloti ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Root Nodules ◽  
Genetic Regulation ◽  
Carbon Sources ◽  
Dicarboxylic Acids ◽  
Phenotypic Analysis ◽  
Gene Encoding ◽  
Type Locus ◽  
Rapid Induction

Abstract The enzyme phosphoenolpyruvate carboxykinase (Pck) catalyzes the first step in the gluconeogenic pathway in most organisms. We are examining the genetic regulation of the gene encoding Pck, pckA, in Rhizobium (now Sinorhizobium) meliloti. This bacterium forms N2-fixing root nodules on alfalfa, and the major energy sources supplied to the bacteria within these nodules are C4-dicarboxylic acids such as malate and succinate. R. meliloti cells growing in glucose minimal medium show very low pckA expression whereas addition of succinate to this medium results in a rapid induction of pckA transcription. We identified spontaneous mutations (rpk) that alter the regulation of pckA expression such that pckA is expressed in media containing the non-inducing carbon sources lactose and glucose. Genetic and phenotypic analysis allowed us to differentiate at least four rpk mutant classes that map to different locations on the R. meliloti chromosome. The wild-type locus corresponding to one of these rpk loci was cloned by complementation, and two Tn5 insertions within the insert DNA that no longer complemented the rpk mutation were identified. The nucleotide sequence of this region revealed that both Tn5 insertions lay within a gene encoding a protein homologous to the Ga1R/LacI family of transcriptional regulators that are involved in metabolism.

scholarly journals Inoculation with Efficient Nitrogen Fixing and Indoleacetic Acid Producing Bacterial Microsymbiont Enhance Tolerance of the Model LegumeMedicago truncatulato Iron Deficiency

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Nadia Kallala ◽  
Wissal M’sehli ◽  
Karima Jelali ◽  
Zribi Kais ◽  
Haythem Mhadhbi
Keyword(s):  
Oxidative Stress ◽  
Iron Deficiency ◽  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Plant Biomass ◽  
High Growth ◽  
Fe Deficiency ◽  
Nitrogen Fixing ◽  
Bacterial Strains ◽  
Negative Effect

The aim of this study was to assess the effect of symbiotic bacteria inoculation on the response ofMedicago truncatulagenotypes to iron deficiency. The present work was conducted on threeMedicago truncatulagenotypes: A17, TN8.20, and TN1.11. Three treatments were performed: control (C), direct Fe deficiency (DD), and induced Fe deficiency by bicarbonate (ID). Plants were nitrogen-fertilized (T) or inoculated with two bacterial strains:Sinorhizobium melilotiTII7 andSinorhizobium medicaeSII4. Biometric, physiological, and biochemical parameters were analyzed. Iron deficiency had a significant lowering effect on plant biomass and chlorophyll content in allMedicago truncatulagenotypes. TN1.11 showed the highest lipid peroxidation and leakage of electrolyte under iron deficiency conditions, which suggest that TN1.11 was more affected than A17 and TN8.20 by Fe starvation. Iron deficiency affected symbiotic performance indices of allMedicago truncatulagenotypes inoculated with bothSinorhizobiumstrains, mainly nodules number and biomass as well as nitrogen-fixing capacity. Nevertheless, inoculation withSinorhizobiumstrains mitigates the negative effect of Fe deficiency on plant growth and oxidative stress compared to nitrogen-fertilized plants. The highest auxin producing strain, TII7, preserves relatively high growth and root biomass and length when inoculated to TN8.20 and A17. On the other hand, both TII7 and SII4 strains improve the performance of sensitive genotype TN1.11 through reduction of the negative effect of iron deficiency on chlorophyll and plant Fe content. The bacterial inoculation improved Fe-deficient plant response to oxidative stress via the induction of the activities of antioxidant enzymes.

scholarly journals Pharmacological activity of new imidazole-4,5-dicarboxylic acid derivatives in dopaminergic transmission suppression ttests in mice and rats

2020 ◽  
Vol 6 (4) ◽  
pp. 51-57
Author(s):  
Ekaterina E. Yakovleva ◽  
Eugeny R. Bychkov ◽  
Maria M. Brusina ◽  
Levon B. Piotrovsky ◽  
Petr D. Shabanov
Keyword(s):  
Locomotor Activity ◽  
Dicarboxylic Acid ◽  
Open Field ◽  
Field Test ◽  
Open Field Test ◽  
Dicarboxylic Acids ◽  
Dopaminergic Transmission ◽  
Dose Dependent ◽  
Derivatives Of ◽  
Experimental Improvement

Objective: To study the antiparkinsonian activity of new 1,2-substituted imidazole-4,5-dicarboxylic acids in dopaminergic transmission suppression tests in mice and rats. Materials and methods: On a model of reserpine extrapyramidal disorders, the derivatives of imidazole-dicarboxylic acids (IEM2258, IEM2248, IEM2247) were injected into the lateral brain ventricles of the mice 30 minutes after injecting reserpine at the doses of 0.1–0.5 mmol. Locomotor activity was analyzed in the Open-field test 2 hours later. In the catalepsy model, the studied agents were injected, using a pre-implanted cannula, with a simultaneous intraperitoneal injection of haloperidol. The severity of catalepsy was assessed with the Morpurgo method. Amantadine was used as a comparator drug in all the tests. Results: It was shown that IEM2258 significantly increased the main indicators of locomotor activity in the Open-field test at all the studied doses. The value of the antiparkinsonian effect of IEM2258 at doses of 0.4–0.5 mmol significantly exceeded that of amantadine. The antiparkinsonian effect of IEM2247 was maximally expressed and was significantly different from those in the control and comparator group at doses of 0.2 and 0.3 mmol. For all the experimental groups, a significant decrease in the manifestations of catalepsy in comparison with control indexes was determined. Discussion: The results made it possible to suggest the involvement of imidazole-4,5-dicarboxylic acids derivatives in the process of experimental improvement of dopaminergic neuromodulation and efficiency in animals. Conclusion: The data showed a significant dose-dependent antiparkinsonian activity of new imidazole-4,5-dicarboxylic acid derivatives, which makes it promising to develop these agents and to further search for effective and safe antiparkinsonian drugs in this pharmacological class. Graphical abstract

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