Статті в журналах: "Malate transport"

1

Osothsilp, C., and R. E. Subden. "Malate transport in Schizosaccharomyces pombe." Journal of Bacteriology 168, no. 3 (1986): 1439–43. http://dx.doi.org/10.1128/jb.168.3.1439-1443.1986.

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2

Agbanyo, F. R., G. Moses, and N. F. Taylor. "L-Malate transport and proton symport in vesicles prepared from Pseudomonas putida." Biochemistry and Cell Biology 64, no. 11 (November 1, 1986): 1190–94. http://dx.doi.org/10.1139/o86-156.

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In vesicles from glucose-grown Pseudomonas putida, L-malate is transported by nonspecific physical diffusion. L-Malate also acts as an electron donor and generates a proton motive force (Δp) of 129 mV which is composed of a membrane potential (Δψ) of 60 mV and a ΔpH of 69 mV. In contrast, vesicles from succinate-grown cells (a) transport L-malate by a carrier-mediated system with a Km value of 14.3 mM and a Vmax of 313 nmol∙mg protein−1∙min−1, (b) generate no Δψ, ΔpH, or Δp when L-malate is the electron donor, and (c) produce an extravesicular alkaline pH during the transport of L-malate. A kinetic analysis of this L-malate-induced proton transport gives a Km value of 16 mM and a Vmax of 667 nmol H+∙mg protein−1∙min−1. This corresponds to a H+/L-malate ratio of 2.1. The failure to generate a Δp in these vesicles is considered, therefore, to be consistent with the induction in succinate-grown cells of an electrogenic proton symport L-malate transport system.

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3

Günzel, Dorothee, Karin Hintz, Simone Durry, and Wolf-Rüdiger Schlue. "Mg2+-Malate Co-Transport, a Mechanism for Na+-Independent Mg2+ Transport in Neurons of the Leech Hirudo medicinalis." Journal of Neurophysiology 94, no. 1 (July 2005): 441–53. http://dx.doi.org/10.1152/jn.01221.2004.

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Mg2+-extrusion from Mg2+-loaded neurons of the leech, Hirudo medicinalis, is mediated mainly by Na+/Mg2+ antiport. However, in a number of leech neurons, Mg2+ is extruded in the nominal absence of extracellular Na+, indicating the existence of an additional, Na+-independent Mg2+ transport mechanism. This mechanism was investigated using electrophysiological and microfluorimetrical techniques. The rate of Na+-independent Mg2+ extrusion from Mg2+-loaded leech neurons was found to be independent of extracellular Ca2+, K+, NO3−, HCO3−, SO42−, HPO42−, and of intra- and extracellular pH. Na+-independent Mg2+ extrusion was not inhibited by 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS), furosemide, ouabain, vanadate, iodoacetate, 4-amino-hippurate, or α-cyano-4-hydroxycinnamate and was not influenced by changes in the membrane potential in voltage-clamp experiments. Na+-independent Mg2+ extrusion was, however, inhibited by the application of 2 mM probenecid, a blocker of organic anion transporters, suggesting that Mg2+ might be co-transported with organic anions. Extracellularly, of all organic anions tested (malate, citrate, lactate, α-ketoglutarate, and 4-amino-hippurate) only high, but physiological, concentrations of malate (30 mM) had a significant inhibitory effect on Na+-independent Mg2+ extrusion. Intracellularly, iontophoretically injected malate, citrate, or fura-2, but not Cl−, α-ketoglutarate, glutamate, succinate, or urate, were stimulating Na+-independent Mg2+ extrusion from those neurons that initially did not extrude Mg2+ in Na+-free solutions. Our data indicate that Mg2+ is co-transported with organic anions, preferably with malate, the predominant extracellular anion in the leech. The proposed model implies that, under experimental conditions, malate drives Mg2+ extrusion, whereas under physiological conditions, malate is actively taken up, driven by Mg2+, so that malate can be metabolized.

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4

Pallotta, Maria Luigia, Alessandra Fratianni, and Salvatore Passarella. "Metabolite transport in isolated yeast mitochondria: fumarate/malate and succinate/malate antiports." FEBS Letters 462, no. 3 (November 30, 1999): 313–16. http://dx.doi.org/10.1016/s0014-5793(99)01535-5.

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5

Krom, Bastiaan P., Ronald Aardema, and Juke S. Lolkema. "Bacillus subtilis YxkJ Is a Secondary Transporter of the 2-Hydroxycarboxylate Transporter Family That Transports l-Malate and Citrate." Journal of Bacteriology 183, no. 20 (October 15, 2001): 5862–69. http://dx.doi.org/10.1128/jb.183.20.5862-5869.2001.

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ABSTRACT The genome of Bacillus subtilis contains two genes that code for membrane proteins that belong to the 2-hydroxycarboxylate transporter family. Here we report the functional characterization of one of the two, yxkJ, which codes for a transporter protein named CimHbs. The gene was cloned and expressed inEscherichia coli and complemented the citrate-negative phenotype of wild-type E. coli and the malate-negative phenotype of the E. coli strain JRG4008, which is defective in malate uptake. Subsequent uptake studies in whole cells expressing CimHbs clearly demonstrated the citrate and malate transport activity of the protein. Immunoblot analysis showed that CimHbs is a 48-kDa protein that is well expressed in E. coli. Studies with right-side-out membrane vesicles demonstrated that CimHbs is an electroneutral proton-solute symporter. No indications were found for the involvement of Na+ ions in the transport process. Inhibition of the uptake catalyzed by CimHbs by divalent metal ions, together with the lack of effect on transport by the chelator EDTA, showed that CimHbs translocates the free citrate and malate anions. Among a large set of substrates tested, only malate, citramalate, and citrate competitively inhibited citrate transport catalyzed by CimHbs. The transporter is strictly stereoselective, recognizing only the S enantiomers of malate and citramalate. Remarkably, though citramalate binds to the transporter, it is not translocated.

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6

Zhang, Lihua, Baiquan Ma, Changzhi Wang, Xingyu Chen, Yong-Ling Ruan, Yangyang Yuan, Fengwang Ma, and Mingjun Li. "MdWRKY126 modulates malate accumulation in apple fruit by regulating cytosolic malate dehydrogenase (MdMDH5)." Plant Physiology 188, no. 4 (January 25, 2022): 2059–72. http://dx.doi.org/10.1093/plphys/kiac023.

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Abstract The content of organic acids greatly influences the taste and storage life of fleshy fruit. Our current understanding of the molecular mechanism of organic acid accumulation in apple (Malus domestica) fruit focuses on the aluminum-activated malate transporter 9/Ma1 gene. In this study, we identified a candidate gene, MdWRKY126, for controlling fruit acidity independent of Ma1 using homozygous recessive mutants of Ma1, namely Belle de Boskoop “BSKP” and Aifeng “AF.” Analyses of transgenic apple calli and flesh and tomato (Solanum lycopersicum) fruit demonstrated that MdWRKY126 was substantially associated with malate content. MdWRKY126 was directly bound to the promoter of the cytoplasmic NAD-dependent malate dehydrogenase MdMDH5 and promoted its expression, thereby enhancing the malate content of apple fruit. In MdWRKY126 overexpressing calli, the mRNA levels of malate-associated transporters and proton pump genes also significantly increased, which contributed to the transport of malate accumulated in the cytoplasm to the vacuole. These findings demonstrated that MdWRKY126 regulates malate anabolism in the cytoplasm and coordinates the transport between cytoplasm and vacuole to regulate malate accumulation. Our study provides useful information to improve our understanding of the complex mechanism regulating apple fruit acidity.

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7

Zoglowek, Cornelia, Silke Krömer, and Hans W. Heldt. "Oxaloacetate and Malate Transport by Plant Mitochondria." Plant Physiology 87, no. 1 (May 1, 1988): 109–15. http://dx.doi.org/10.1104/pp.87.1.109.

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8

Wang, Yuqi, Ruihong Li, Demou Li, Xiaomin Jia, Dangwei Zhou, Jianyong Li, Sangbom M. Lyi, et al. "NIP1;2 is a plasma membrane-localized transporter mediating aluminum uptake, translocation, and tolerance in Arabidopsis." Proceedings of the National Academy of Sciences 114, no. 19 (April 24, 2017): 5047–52. http://dx.doi.org/10.1073/pnas.1618557114.

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Members of the aquaporin (AQP) family have been suggested to transport aluminum (Al) in plants; however, the Al form transported by AQPs and the roles of AQPs in Al tolerance remain elusive. Here we report that NIP1;2, a plasma membrane-localized member of the Arabidopsis nodulin 26-like intrinsic protein (NIP) subfamily of the AQP family, facilitates Al-malate transport from the root cell wall into the root symplasm, with subsequent Al xylem loading and root-to-shoot translocation, which are critical steps in an internal Al tolerance mechanism in Arabidopsis. We found that NIP1;2 transcripts are expressed mainly in the root tips, and that this expression is enhanced by Al but not by other metal stresses. Mutations in NIP1;2 lead to hyperaccumulation of toxic Al3+ in the root cell wall, inhibition of root-to-shoot Al translocation, and a significant reduction in Al tolerance. NIP1;2 facilitates the transport of Al-malate, but not Al3+ ions, in both yeast and Arabidopsis. We demonstrate that the formation of the Al-malate complex in the root tip apoplast is a prerequisite for NIP1;2-mediated Al removal from the root cell wall, and that this requires a functional root malate exudation system mediated by the Al-activated malate transporter, ALMT1. Taken together, these findings reveal a critical linkage between the previously identified Al exclusion mechanism based on root malate release and an internal Al tolerance mechanism identified here through the coordinated function of NIP1;2 and ALMT1, which is required for Al removal from the root cell wall, root-to-shoot Al translocation, and overall Al tolerance in Arabidopsis.

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9

Ramesh, Sunita A., Muhammad Kamran, Wendy Sullivan, Larissa Chirkova, Mamoru Okamoto, Fien Degryse, Michael McLaughlin, Matthew Gilliham, and Stephen D. Tyerman. "Aluminum-Activated Malate Transporters Can Facilitate GABA Transport." Plant Cell 30, no. 5 (April 4, 2018): 1147–64. http://dx.doi.org/10.1105/tpc.17.00864.

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10

Waters, James K., Thomas P. Mawhinney, and David W. Emerich. "Nitrogen Assimilation and Transport by Ex Planta Nitrogen-Fixing Bradyrhizobium diazoefficiens Bacteroids Is Modulated by Oxygen, Bacteroid Density and l-Malate." International Journal of Molecular Sciences 21, no. 20 (October 13, 2020): 7542. http://dx.doi.org/10.3390/ijms21207542.

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Symbiotic nitrogen fixation requires the transfer of fixed organic nitrogen compounds from the symbiotic bacteria to a host plant, yet the chemical nature of the compounds is in question. Bradyrhizobium diazoefficiens bacteroids were isolated anaerobically from soybean nodules and assayed at varying densities, varying partial pressures of oxygen, and varying levels of l-malate. Ammonium was released at low bacteroid densities and high partial pressures of oxygen, but was apparently taken up at high bacteroid densities and low partial pressures of oxygen in the presence of l-malate; these later conditions were optimal for amino acid excretion. The ratio of partial pressure of oxygen/bacteroid density of apparent ammonium uptake and of alanine excretion displayed an inverse relationship. Ammonium uptake, alanine and branch chain amino acid release were all dependent on the concentration of l-malate displaying similar K0.5 values of 0.5 mM demonstrating concerted regulation. The hyperbolic kinetics of ammonium uptake and amino acid excretion suggests transport via a membrane carrier and also suggested that transport was rate limiting. Glutamate uptake displayed exponential kinetics implying transport via a channel. The chemical nature of the compounds released were dependent upon bacteroid density, partial pressure of oxygen and concentration of l-malate demonstrating an integrated metabolism.

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11

Bryce, JH, and JT Wiskich. "Effect of NAD and Rotenone on the Partitioning of Malate Oxidation Between Malate Dehydrogenase and Malic Enzyme in Isolated Plant Mitochondria." Functional Plant Biology 12, no. 3 (1985): 229. http://dx.doi.org/10.1071/pp9850229.

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Our aim was to determine whether there is a specific link between NAD-malic enzyme and the rotenone- insensitive bypass of electron transport. Mitochondria were isolated from fresh beetroot tissue, aged beetroot slices, and turnips. Oxygen uptake and pyruvate production were measured in reactions where these mitochondria were metabolizing malate at pH 6.8 in the presence of glutamate, to facilitate the removal of oxaloacetate, and in its absence. In the absence of glutamate there was substantial activity of malic enzyme. NAD+ (577 �M) prevented a fall in oxygen uptake by stimulating malic enzyme. Rotenone (19 �M) reduced oxygen uptake. This inhibited rate was stimulated by NAD+ due, in particular, to a stimulation of malic enzyme. We conclude that the stimulation of malate metabolism by NAD+ is accounted for by malic enzyme due to the unfavourable equilibrium of malate dehydrogenase for malate oxidation and the resultant accumulation of oxaloacetate, and not to any specific link between malic enzyme and the rotenone-insensitive bypass. In the presence of glutamate, malate dehydrogenase was the predominant malate metabolizing enzyme. Oxygen uptake and malic enzyme were stimulated and inhibited by NAD+ and rotenone, respectively. In the presence of rotenone, NAD+ stimulated oxygen uptake and increased the percentage due to malic enzyme. This stimulation is accounted for by the higher Kin of the rotenone-insensitive dehydrogenase for NADH and the unfavourable equilibrium position of malate dehydrogenase resulting in activation of malic enzyme only. We conclude that malic enzyme is not specifically linked to the rotenone-insensitive pathway of electron transport. This has important implications for the regulation of energy metabolism in plants.

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12

Sallal, A. K. J., and N. A. Nimer. "The Presence of Malate Dehydrogenase in Thylakoids of Anabaena cylindrical Nostoc muscorum and Chlorogloeopsis fritschii." Zeitschrift für Naturforschung C 45, no. 3-4 (April 1, 1990): 249–52. http://dx.doi.org/10.1515/znc-1990-3-418.

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Abstract The location of malate dehydrogenase in the cyanobacteria, Anabaena cylindrica, Nostoc muscorum and Chlorogloeopsis fritschii was investigated by the fractionation of cell-free extracts. The bulk of the enzyme activity was associated with the thylakoid membrane fraction, which also exhibited complete photosynthetic electron transport reactions. Malate dehydrogenase activity and photosystem II activities were inhibited by homologous antisera raised against isolated thylakoid membranes.

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13

Booth, Nicholas J., Penelope M. C. Smith, Sunita A. Ramesh, and David A. Day. "Malate Transport and Metabolism in Nitrogen-Fixing Legume Nodules." Molecules 26, no. 22 (November 15, 2021): 6876. http://dx.doi.org/10.3390/molecules26226876.

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Legumes form a symbiosis with rhizobia, a soil bacterium that allows them to access atmospheric nitrogen and deliver it to the plant for growth. Biological nitrogen fixation occurs in specialized organs, termed nodules, that develop on the legume root system and house nitrogen-fixing rhizobial bacteroids in organelle-like structures termed symbiosomes. The process is highly energetic and there is a large demand for carbon by the bacteroids. This carbon is supplied to the nodule as sucrose, which is broken down in nodule cells to organic acids, principally malate, that can then be assimilated by bacteroids. Sucrose may move through apoplastic and/or symplastic routes to the uninfected cells of the nodule or be directly metabolised at the site of import within the vascular parenchyma cells. Malate must be transported to the infected cells and then across the symbiosome membrane, where it is taken up by bacteroids through a well-characterized dct system. The dicarboxylate transporters on the infected cell and symbiosome membranes have been functionally characterized but remain unidentified. Proteomic and transcriptomic studies have revealed numerous candidates, but more work is required to characterize their function and localise the proteins in planta. GABA, which is present at high concentrations in nodules, may play a regulatory role, but this remains to be explored.

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14

Amaral, Alexandre Umpierrez, Cristiane Cecatto, Estela Natasha Brandt Busanello, César Augusto João Ribeiro, Daniela Rodrigues Melo, Guilhian Leipnitz, Roger Frigério Castilho, and Moacir Wajner. "Ethylmalonic acid impairs brain mitochondrial succinate and malate transport." Molecular Genetics and Metabolism 105, no. 1 (January 2012): 84–90. http://dx.doi.org/10.1016/j.ymgme.2011.10.006.

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15

Cheffings, C. M., O. Pantoja, F. M. Ashcroft, and J. A. C. Smith. "Malate transport and vacuolar ion channels in CAM plants." Journal of Experimental Botany 48, Special (March 1, 1997): 623–31. http://dx.doi.org/10.1093/jxb/48.special_issue.623.

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16

Wu, Liujie, Ayan Sadhukhan, Yuriko Kobayashi, Naohisa Ogo, Mutsutomo Tokizawa, Raj Kishan Agrahari, Hiroki Ito, et al. "Involvement of phosphatidylinositol metabolism in aluminum-induced malate secretion in Arabidopsis." Journal of Experimental Botany 70, no. 12 (April 12, 2019): 3329–42. http://dx.doi.org/10.1093/jxb/erz179.

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Abstract To identify the upstream signaling of aluminum-induced malate secretion through aluminum-activated malate transporter 1 (AtALMT1), a pharmacological assay using inhibitors of human signal transduction pathways was performed. Early aluminum-induced transcription of AtALMT1 and other aluminum-responsive genes was significantly suppressed by phosphatidylinositol 4-kinase (PI4K) and phospholipase C (PLC) inhibitors, indicating that the PI4K–PLC metabolic pathway activates early aluminum signaling. Inhibitors of phosphatidylinositol 3-kinase (PI3K) and PI4K reduced aluminum-activated malate transport by AtALMT1, suggesting that both the PI3K and PI4K metabolic pathways regulate this process. These results were validated using T-DNA insertion mutants of PI4K and PI3K-RNAi lines. A human protein kinase inhibitor, putatively inhibiting homologous calcineurin B-like protein-interacting protein kinase and/or Ca-dependent protein kinase in Arabidopsis, suppressed late-phase aluminum-induced expression of AtALMT1, which was concomitant with the induction of an AtALMT1 repressor, WRKY46, and suppression of an AtALMT1 activator, Calmodulin-binding transcription activator 2 (CAMTA2). In addition, a human deubiquitinase inhibitor suppressed aluminum-activated malate transport, suggesting that deubiquitinases can regulate this process. We also found a reduction of aluminum-induced citrate secretion in tobacco by applying inhibitors of PI3K and PI4K. Taken together, our results indicated that phosphatidylinositol metabolism regulates organic acid secretion in plants under aluminum stress.

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17

Yu, JW, and KC Woo. "Ammonia Assimilation and Metabolite Transport in Isolated Chloroplasts. II. Malate Stimulates Ammonia Assimilation in Chloroplasts Isolated From Leaves of Dicotyledonous but Not Monocotyledonous Species." Functional Plant Biology 19, no. 6 (1992): 659. http://dx.doi.org/10.1071/pp9920659.

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Malate stimulated NH3 assimilation, as determined by a (2-oxoglutarate, NH3)-dependent O2 evolution system, by up to 3-fold in chloroplasts isolated from leaves of dicot but not monocot species. This difference was apparently correlated with the endogenous metabolite pools present in these chloroplast preparations. During NH3 assimilation the glutamate and glutamine pools were large in spinach (dicot) but small in oat chloroplasts. The reverse was the case for the 2-oxoglutarate (2-OG) pool. The addition of malate substantially increased the glutamate, glutamine and 2-OG pools in spinach chloroplasts but had little effect in oat chloroplasts. This suggests that the supply of 2-OG was apparently limiting NH3 assimilation in spinach chloroplasts. Malate increased this supply and, consequently, stimulated NH3 assimilation. On the other hand, NH3 assimilation in oat chloroplasts seemed to be limited by the supply of glutamate and glutamine which could not be overcome by the addition of malate. Chloroplasts were also isolated from oat seedlings watered with high nutrient solution. The rates of NH3 assimilation in these organelles exceeded those obtained in spinach chloroplasts. But the addition of malate had little effect on (2-OG, NH3)-dependent O2 evolution in these oat chloroplasts. Since malate did not inhibit this activity it is conceivable that it still might play a role, albeit a 'passive' role, in serving as a counter-ion for 2-OG uptake via the 2-OG translocator and glutamate export via the Dct translocator during NH3 assimilation.

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18

Ramesh, Sunita A., Yu Long, Abolfazl Dashtbani-Roozbehani, Matthew Gilliham, Melissa H. Brown та Stephen D. Tyerman. "Picrotoxin Delineates Different Transport Configurations for Malate and γ Aminobutyric Acid through TaALMT1". Biology 11, № 8 (2 серпня 2022): 1162. http://dx.doi.org/10.3390/biology11081162.

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Plant-derived pharmacological agents have been used extensively to dissect the structure–function relationships of mammalian GABA receptors and ion channels. Picrotoxin is a non-competitive antagonist of mammalian GABAA receptors. Here, we report that picrotoxin inhibits the anion (malate) efflux mediated by wheat (Triticum aestivum) ALMT1 but has no effect on GABA transport. The EC50 for inhibition was 0.14 nM and 0.18 nM when the ALMTs were expressed in tobacco BY2 cells and in Xenopus oocytes, respectively. Patch clamping of the oocyte plasma membrane expressing wheat ALMT1 showed that picrotoxin inhibited malate currents from both sides of the membrane. These results demonstrate that picrotoxin inhibits anion efflux effectively and can be used as a new inhibitor to study the ion fluxes mediated by ALMT proteins that allow either GABA or anion transport.

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19

Marigo, G., H. Bouyssou, and D. Laborie. "Evidence for a Malate Transport into Vacuoles Isolated fromCatharanthus roseusCells." Botanica Acta 101, no. 2 (May 1988): 187–91. http://dx.doi.org/10.1111/j.1438-8677.1988.tb00031.x.

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20

Queirós, O., M. Casal, S. Althoff, P. Moradas-Ferreira, and C. Leão. "Isolation and characterization ofKluyveromyces marxianus mutants deficient in malate transport." Yeast 14, no. 5 (March 30, 1998): 401–7. http://dx.doi.org/10.1002/(sici)1097-0061(19980330)14:5<401::aid-yea234>3.0.co;2-t.

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21

Rustin, P., and C. Lance. "Succinate-driven reverse electron transport in the respiratory chain of plant mitochondria. The effects of rotenone and adenylates in relation to malate and oxaloacetate metabolism." Biochemical Journal 274, no. 1 (February 15, 1991): 249–55. http://dx.doi.org/10.1042/bj2740249.

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The effects of rotenone on the succinate-driven reduction of matrix nicotinamide nucleotides were investigated in Percoll-purified mitochondria from potato (Solanum tuberosum) tubers. Depending on the presence of ADP or ATP, rotenone caused an increase or a decrease in the level of reduction of the matrix nicotinamide nucleotides. The increase in the reduction induced by rotenone in the presence of ADP was linked to the oxidation of the malate resulting from the oxidation of succinate. Depending on the experimental conditions, malic enzyme (at pH 6.6 or in the presence of added CoA) or malate dehydrogenase (at pH 7.9) were involved in this oxidation. At pH 7.9, the oxaloacetate produced progressively inhibited the succinate dehydrogenase. In the presence of ATP the production of oxaloacetate was stopped, and succinate dehydrogenase was protected from inhibition by oxaloacetate. However, previously accumulated oxaloacetate transitorily decreased the level of the reduction of the NAD+ driven by succinate, by causing the reversal of the malate dehydrogenase reaction. Under these conditions (i.e. presence of ATP), rotenone strongly inhibited the reduction of NAD+ by succinate-driven reverse electron flow. No evidence for an active reverse electron transport through a rotenone-insensitive path could be obtained. The inhibitory effect of rotenone was masked if malate had previously accumulated, owing to the malate-oxidizing enzymes which reduced part or all of the matrix NAD+.

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22

O’Donnell, J. Michael, Lawrence T. White, and E. Douglas Lewandowski. "Mitochondrial transporter responsiveness and metabolic flux homeostasis in postischemic hearts." American Journal of Physiology-Heart and Circulatory Physiology 277, no. 3 (September 1, 1999): H866—H873. http://dx.doi.org/10.1152/ajpheart.1999.277.3.h866.

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The transport of metabolites between mitochondria and cytosol via the α-ketoglutarate-malate carrier serves to balance flux between the two spans of the tricarboxylic acid (TCA) cycle but is reduced in stunned myocardium. To examine the mechanism for reduced transporter activity, we followed the postischemic response of metabolite influx/efflux from mitochondria to stimulation of the malate-aspartate (MA) shuttle. Isolated rabbit hearts were either perfused with 2.5 mM [2-13C]acetate ( n = 7) or similarly reperfused ( n = 5) after 10-min ischemia. In other hearts, the MA shuttle was stimulated with a high cytosolic redox state (NADH) induced by 2.5 mM lactate in normal ( n = 6) or reperfused hearts ( n = 7). In normal hearts, the MA shuttle response accelerated transport from 8.3 ± 3.4 to 16.2 ± 5.0 μmol ⋅ min−1 ⋅ g dry wt−1. Although transport was reduced in stunned hearts, the MA shuttle was responsive to cytosolic NADH load, increasing transport from 3.4 ± 1.0 to 9.8 ± 3.7 μmol ⋅ min−1 ⋅ g dry wt−1. Therefore, metabolite exchange remains intact in stunned myocardium but responds to changes in TCA cycle flux regulation.

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23

Whitehead, Lynne F., Stephen D. Tyerman, and David A. Day. "Polyamines as potential regulators of nutrient exchange across the peribacteroid membrane in soybean root nodules." Functional Plant Biology 28, no. 7 (2001): 677. http://dx.doi.org/10.1071/pp01025.

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The effect of cytoplasmic polyamines on peribacteroid membrane transport processes in soybean (Glycine max L.) was investigated. The concentration of free polyamines in soybean nodule cytoplasm has been estimated by others to be in the micromolar range. The H+ -ATPase was inhibited by 37 and 54% by 200 µM spermidine and putrescine, respectively. Spermine applied to the cytoplasmic face of the peribacteroid membrane was found to inhibit both inward and outward currents through a non-selective cation channel permeable to ammonium (K d 2.1 µM at –100 mV). Malate transport into intact symbiosomes was reduced by 15–30% by 15 mM spermidine, cadaverine and putrescine. A non-specific stimulation of malate transport by polycations was found to occur at concentrations in the micromolar range. The results suggest that polyamines can affect all the peribacteroid membrane transport processes tested. In particular, we conclude that the combined inhibitory effects of polyamines on the ATPase and the ammonium channel have the potential to reduce nitrogen supply to the plant in vivo. The possibility of competing polyamine and ureide synthesis in the nodule is discussed.

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24

Pajor, Ana M., Rama Gangula, and Xiaozhou Yao. "Cloning and functional characterization of a high-affinity Na+/dicarboxylate cotransporter from mouse brain." American Journal of Physiology-Cell Physiology 280, no. 5 (May 1, 2001): C1215—C1223. http://dx.doi.org/10.1152/ajpcell.2001.280.5.c1215.

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Neurons contain a high-affinity Na+/dicarboxylate cotransporter for absorption of neurotransmitter precursor substrates, such as α-ketoglutarate and malate, which are subsequently metabolized to replenish pools of neurotransmitters, including glutamate. We have isolated the cDNA coding for a high-affinity Na+/dicarboxylate cotransporter from mouse brain, called mNaDC-3. The mRNA coding for mNaDC-3 is found in brain and choroid plexus as well as in kidney and liver. The mNaDC-3 transporter has a broad substrate specificity for dicarboxylates, including succinate, α-ketoglutarate, fumarate, malate, and dimethylsuccinate. The transport of citrate is relatively insensitive to pH, but the transport of succinate is inhibited by acidic pH. The Michaelis-Menten constant for succinate in mNaDC-3 is 140 μM in transport assays and 16 μM at −50 mV in two-electrode voltage clamp assays. Transport is dependent on sodium, although lithium can partially substitute for sodium. In conclusion, mNaDC-3 likely codes for the high-affinity Na+/dicarboxylate cotransporter in brain, and it has some unusual electrical properties compared with the other members of the family.

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25

Camarasa, Carole, Frédérique Bidard, Muriel Bony, Pierre Barre, and Sylvie Dequin. "Characterization of Schizosaccharomyces pombe Malate Permease by Expression in Saccharomyces cerevisiae." Applied and Environmental Microbiology 67, no. 9 (September 1, 2001): 4144–51. http://dx.doi.org/10.1128/aem.67.9.4144-4151.2001.

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ABSTRACT In Saccharomyces cerevisiae, l-malic acid transport is not carrier mediated and is limited to slow, simple diffusion of the undissociated acid. Expression in S. cerevisiae of the MAE1 gene, encodingSchizosaccharomyces pombe malate permease, markedly increased l-malic acid uptake in this yeast. In this strain, at pH 3.5 (encountered in industrial processes),l-malic acid uptake involves Mae1p-mediated transport of the monoanionic form of the acid (apparent kinetic parameters:V max = 8.7 nmol/mg/min;Km = 1.6 mM) and some simple diffusion of the undissociated l-malic acid (Kd = 0.057 min−1). As total l-malic acid transport involved only low levels of diffusion, the Mae1p permease was further characterized in the recombinant strain. l-Malic acid transport was reversible and accumulative and depended on both the transmembrane gradient of the monoanionic acid form and the ΔpH component of the proton motive force. Dicarboxylic acids with stearic occupation closely related to l-malic acid, such as maleic, oxaloacetic, malonic, succinic and fumaric acids, inhibitedl-malic acid uptake, suggesting that these compounds use the same carrier. We found that increasing external pH directly inhibited malate uptake, resulting in a lower initial rate of uptake and a lower level of substrate accumulation. In S. pombe, proton movements, as shown by internal acidification, accompanied malate uptake, consistent with the proton/dicarboxylate mechanism previously proposed. Surprisingly, no proton fluxes were observed during Mae1p-mediated l-malic acid import inS. cerevisiae, and intracellular pH remained constant. This suggests that, in S. cerevisiae, either there is a proton counterflow or the Mae1p permease functions differently from a proton/dicarboxylate symport.

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26

Takanashi, Kojiro, Takayuki Sasaki, Tomohiro Kan, Yuka Saida, Akifumi Sugiyama, Yoko Yamamoto, and Kazufumi Yazaki. "A Dicarboxylate Transporter, LjALMT4, Mainly Expressed in Nodules of Lotus japonicus." Molecular Plant-Microbe Interactions® 29, no. 7 (July 2016): 584–92. http://dx.doi.org/10.1094/mpmi-04-16-0071-r.

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Legume plants can establish symbiosis with soil bacteria called rhizobia to obtain nitrogen as a nutrient directly from atmospheric N2 via symbiotic nitrogen fixation. Legumes and rhizobia form nodules, symbiotic organs in which fixed-nitrogen and photosynthetic products are exchanged between rhizobia and plant cells. The photosynthetic products supplied to rhizobia are thought to be dicarboxylates but little is known about the movement of dicarboxylates in the nodules. In terms of dicarboxylate transporters, an aluminum-activated malate transporter (ALMT) family is a strong candidate responsible for the membrane transport of carboxylates in nodules. Among the seven ALMT genes in the Lotus japonicus genome, only one, LjALMT4, shows a high expression in the nodules. LjALMT4 showed transport activity in a Xenopus oocyte system, with LjALMT4 mediating the efflux of dicarboxylates including malate, succinate, and fumarate, but not tricarboxylates such as citrate. LjALMT4 also mediated the influx of several inorganic anions. Organ-specific gene expression analysis showed LjALMT4 mRNA mainly in the parenchyma cells of nodule vascular bundles. These results suggest that LjALMT4 may not be involved in the direct supply of dicarboxylates to rhizobia in infected cells but is responsible for supplying malate as well as several anions necessary for symbiotic nitrogen fixation, via nodule vasculatures.

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27

Yu, JW, and KC Woo. "Ammonia Assimilation and Metabolite Transport in Isolated Chloroplasts. I. Kinetic Measurement of 2-Oxoglutarate and Malate Uptake Via the 2-Oxoglutarate Translocator in Oat and Spinach Chloroplasts." Functional Plant Biology 19, no. 6 (1992): 653. http://dx.doi.org/10.1071/pp9920653.

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The stable double-layer silicone centrifugation system was used to determine the kinetic properties of the 2-oxoglutarate (2-OG) translocator in isolated oat and spinach chloroplasts. The uptake of [14C]2-OG and [14C]malate via the 2-OG translocator were measured in the presence of 20 mM glutamate in chloroplasts preloaded with unlabelled 2-OG. The characteristics of the general dicarboxylate (Dct) translocator were also determined using chloroplasts preloaded with glutamate. The Vmax values obtained for transport activity via the 2-OG translocator in oat and spinach chloroplasts exceeded 150 μmol mg-1 Chl h-1 and for the Dct translocator less than 100 μmol mg-1 Chl h-1. The K� (malate) values of the 2-OG and Dct translocators also showed large differences in the two species. In spinach chloroplasts they were 2.7 and 0.6 mM for the 2-OG and Dct translocators respectively whereas, in oat chloroplasts the corresponding values were 2.7 and 1.4 mM. This suggests that, in spinach, malate would be transported into the chloroplasts preferentially via the Dct translocator, thus providing a kinetic basis for the 'push and pull' mechanism proposed for dicarboxylate transport during photorespiratory NH3 recycling in the 2-translocator model.

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28

Fratianni, Alessandra, Donato Pastore, Maria Luigia Pallotta, Donato Chiatante, and Salvatore Passarella. "Increase of Membrane Permeability of Mitochondria Isolated from Water Stress Adapted Potato Cells." Bioscience Reports 21, no. 1 (February 1, 2001): 81–91. http://dx.doi.org/10.1023/a:1010490219357.

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In order to gain some insight into mitochondria permeability under water stress, intact coupled mitochondria were isolated from water stress adapted potato cells and investigations were made of certain transport processes including the succinate/malate and ADP/ATP exchanges, the plant mitochondrial ATP-sensitive potassium channel (PmitoKATP) and the plant uncoupling mitochondrial protein (PUMP). The VmaxL values measured for succinate/malate and ADP/ATP carriers, as photometrically investigated, as well as the same values for the PmitoATP and the PUMP were found to increase; this suggested that mitochondria adaptation to water stress can cause an increase in the membrane permeability.

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29

Ratajczak, Rafael, Ulrich Lüttge, Pedro Gonzalez, and E. d. Etxeberria. "Malate and malate-channel antibodies inhibit electrogenic and ATP-dependent citrate transport across the tonoplast of citrus juice cells." Journal of Plant Physiology 160, no. 11 (January 2003): 1313–17. http://dx.doi.org/10.1078/0176-1617-01147.

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30

Liu, Jingjing, Zhipeng Xie, Hyun-dong Shin, Jianghua Li, Guocheng Du, Jian Chen, and Long Liu. "Rewiring the reductive tricarboxylic acid pathway and L-malate transport pathway of Aspergillus oryzae for overproduction of L-malate." Journal of Biotechnology 253 (July 2017): 1–9. http://dx.doi.org/10.1016/j.jbiotec.2017.05.011.

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31

Zhang, Jiu-Cheng, Xiao-Na Wang, Wei Sun, Xiao-Fei Wang, Xian-Song Tong, Xing-Long Ji, Jian-Ping An, Qiang Zhao, Chun-Xiang You, and Yu-Jin Hao. "Phosphate regulates malate/citrate-mediated iron uptake and transport in apple." Plant Science 297 (August 2020): 110526. http://dx.doi.org/10.1016/j.plantsci.2020.110526.

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32

Hao, Pengchao, Jian Xia, Jie Liu, Martin Di Donato, Konrad Pakula, Aurélien Bailly, Michal Jasinski, and Markus Geisler. "Auxin-transporting ABC transporters are defined by a conserved D/E-P motif regulated by a prolylisomerase." Journal of Biological Chemistry 295, no. 37 (July 22, 2020): 13094–105. http://dx.doi.org/10.1074/jbc.ra120.014104.

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The plant hormone auxin must be transported throughout plants in a cell-to-cell manner to affect its various physiological functions. ABCB transporters are critical for this polar auxin distribution, but the regulatory mechanisms controlling their function is not fully understood. The auxin transport activity of ABCB1 was suggested to be regulated by a physical interaction with FKBP42/Twisted Dwarf1 (TWD1), a peptidylprolyl cis-trans isomerase (PPIase), but all attempts to demonstrate such a PPIase activity by TWD1 have failed so far. By using a structure-based approach, we identified several surface-exposed proline residues in the nucleotide binding domain and linker of Arabidopsis ABCB1, mutations of which do not alter ABCB1 protein stability or location but do affect its transport activity. P1008 is part of a conserved signature D/E-P motif that seems to be specific for auxin-transporting ABCBs, which we now refer to as ATAs. Mutation of the acidic residue also abolishes auxin transport activity by ABCB1. All higher plant ABCBs for which auxin transport has been conclusively proven carry this conserved motif, underlining its predictive potential. Introduction of this D/E-P motif into malate importer, ABCB14, increases both its malate and its background auxin transport activity, suggesting that this motif has an impact on transport capacity. The D/E-P1008 motif is also important for ABCB1-TWD1 interactions and activation of ABCB1-mediated auxin transport by TWD1. In summary, our data imply a new function for TWD1 acting as a putative activator of ABCB-mediated auxin transport by cis-trans isomerization of peptidyl-prolyl bonds.

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33

Minardi, Bruno Degaspari, Ana Paula Lorenzen Voytena, Marisa Santos, and Áurea Maria Randi. "The Epiphytic FernElaphoglossum luridum(Fée) Christ. (Dryopteridaceae) from Central and South America: Morphological and Physiological Responses to Water Stress." Scientific World Journal 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/817892.

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Elaphoglossum luridum(Fée) Christ. (Dryopteridaceae) is an epiphytic fern of the Atlantic Forest (Brazil). Anatomical and physiological studies were conducted to understand how this plant responds to water stress. TheE. luridumfrond is coriaceus and succulent, presenting trichomes, relatively thick cuticle, and sinuous cell walls in both abaxial and adaxial epidermis. Three treatments were analyzed: control, water deficit, and abscisic acid (ABA). Physiological studies were conducted through analysis of relative water content (RWC), photosynthetic pigments, chlorophyll a fluorescence, and malate content. No changes in RWC were observed among treatments; however, significant decreases in chlorophyll a content and photosynthetic parameters, including optimal irradiance (Iopt) and maximum electron transport rate (ETRmax), were determined by rapid light curves (RLC). No evidence of crassulacean acid metabolism (CAM) pathway was observed inE. luridumin response to either water deficit or exogenous application of ABA. On the other hand, malate content decreased in theE. luridumfrond after ABA treatment, seeming to downregulate malate metabolism at night, possibly through tricarboxylic acid (TCA) cycle regulation.

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34

Aw, T. Y., B. S. Andersson, and D. P. Jones. "Mitochondrial transmembrane ion distribution during anoxia." American Journal of Physiology-Cell Physiology 252, no. 4 (April 1, 1987): C356—C361. http://dx.doi.org/10.1152/ajpcell.1987.252.4.c356.

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The distribution of pyruvate, phosphate, malate, citrate, K+, aspartate, glutamate, ADP, and ATP between the mitochondrial and cytosolic compartments was studied in isolated rat hepatocytes exposed to 30 min anoxia. The results show that pyruvate and citrate gradients are comparable to aerobic values, indicating that the pH gradient across the membrane under anaerobic conditions is comparable to that under normal aerobic conditions. In contrast, the distribution of phosphate, malate, ATP, ADP, aspartate, and glutamate suggests that transport of these species may be inhibited during anoxia. The results are discussed in terms of potential regulation of mitochondrial function to provide a quiescent anoxic state that is capable of recovering normal function on reoxygenation.

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35

Pereira, Paula Natália, James Andrew Charles Smith, Eduardo Purgatto, and Helenice Mercier. "Proton and anion transport across the tonoplast vesicles in bromeliad species." Functional Plant Biology 44, no. 6 (2017): 646. http://dx.doi.org/10.1071/fp16293.

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Crassulacean acid metabolism (CAM) is one of the key innovations in the Neotropical family Bromeliaceae that has enabled many of its species to occupy seasonally water-limited terrestrial environments or microclimatically arid epiphytic niches. However, the relationship between CAM activity and the transport processes responsible for vacuolar organic-acid accumulation at night has not been systematically explored in this family. In the present investigation, ATP- and PPi-dependent proton transport rates were studied in tonoplast membrane vesicles isolated from leaves of six CAM and one C3 species of bromeliads. A consistent feature of these species was the high activity of the tonoplast ATP-driven H+ pump, which, when averaged across the seven species tested, showed a higher specific activity than the tonoplast PPi-driven H+ pump. For all CAM species, the rate of ATP-dependent proton transport into the tonoplast vesicles was strongly influenced by the nature of the balancing organic-acid anion, which displayed the following order of effectiveness: fumarate > malate > citrate. Measurements of leaf organic-acid content in six CAM bromeliads at dusk and dawn showed that nocturnal accumulation of malate exceeded citrate by a factor of ~2.4–20.0-fold in five of six bromeliad species used in this study, demonstrating a close correlation between the CAM rhythm and the intrinsic properties of the vacuolar membrane across which these organic acids are transported.

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36

Bender, K., P. Newsholme, L. Brennan та P. Maechler. "The importance of redox shuttles to pancreatic β-cell energy metabolism and function". Biochemical Society Transactions 34, № 5 (1 жовтня 2006): 811–14. http://dx.doi.org/10.1042/bst0340811.

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The coupling of cytosolic glycolytic NADH production with the mitochondrial electron transport chain is crucial for pancreatic β-cell function and energy metabolism. The activity of lactate dehydrogenase in the β-cell is low, thus glycolysis-derived electrons are transported towards the mitochondrial matrix by a NADH shuttle system, which in turn regenerates cytosolic NAD+. Mitochondrial electron transport then produces ATP, the main coupling factor for insulin secretion. Aralar1, a Ca2+-sensitive member of the malate–aspartate shuttle expressed in β-cells, has been found to play a significant role in nutrient-stimulated insulin secretion and β-cell function. Increased capacity of Aralar1 enhances the responsiveness of the cell to glucose. Conversely, inhibition of the malate–aspartate shuttle results in impaired glucose metabolism and insulin secretion. Current research investigates potentiating or attenuating activities of various amino acids on insulin secretion, mitochondrial membrane potential and NADH production in Aralar1-overexpressing β-cells. This work may provide evidence for a central role of Aralar1 in the regulation of nutrient metabolism in the β-cells.

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37

Мазур, I. Mazur, Нагорная, E. Nagornaya, Кучеренко, L. Kucherenko, Авраменко, and N. Avramenko. "Pharmacological Modulation of Compensatory Malate-Aspartate Shuttle of Energy Metabolism by Metabolitotropic Cardioprotector Angiolin in Experimental Myocardial Infarction." Journal of New Medical Technologies 21, no. 2 (August 13, 2014): 80–83. http://dx.doi.org/10.12737/5005.

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Cardioprotector Angiolin with original structure 3-methyl-1,2,4-triazolyl-5-thioacetate (S)-2,6-diaminohexanoic acid and its dosage form – 2,5% solution for injection – were developed by Scientific and Production Corporation «Pharmatron». Angiolin administration in dose of 50 mg/kg to the animals with pituitrin-isadrin myocardial infarction resulted in normalization of energy metabolism of the heart due to intensification of aerobic reactions and compensatory activation of malate-aspartate shuttle, in decrease of anaerobic glycolysis and improvement of mitochondria functions, saving use of oxidation substrates and activation of energy transport. Thus, in myocardium of the animals with myocardial infarction which received Angiolin the increase of ATP production was noted against the background of the increase of levels of such malate-aspartate shuttle components as malate, aspartate, glutamate and malate dehydrogenase activation as well as isocitrate content growth and lactate level decrease as compared with untreated animals group. Increase of glycogen and glucose 6-phosphate contents, increase of mitochondrial and cytosolic creatine phosphokinase activity took place in animals’ myocardium when administrating Angiolin. Thus Angiolin administration at myocardial infarction forms resistance of cardiac hystiocytes to hypoxia due to energy pathways change which supposes mobilization of mechanisms of protons supply for oxidative phosphorylation and saving use of deficient oxygen. Angiolin therapeutical efficiency significantly exceeds the efficiency of reference drug Mildronate (100 mg/kg).

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38

O’Loughlin, Kieran L., Hans Minderman, Laurie A. Ford, and Maria R. Baer. "Amonafide L-Malate Bypasses Multidrug Resistance Proteins in Secondary Acute Myeloid Leukemia." Blood 110, no. 11 (November 16, 2007): 2380. http://dx.doi.org/10.1182/blood.v110.11.2380.2380.

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Abstract Amonafide L-malate, a DNA intercalating agent and ATP-independent topoisomerase 2 inhibitor showed promising clinical activity in combination with cytarabine in a Phase 2 clinical trial in secondary acute myeloid leukemia (S-AML), with a complete remission (CR) rate of 45% (Erba, et al., JCO25:373s, 2007), and is currently in a Phase 3 clinical trial. We hypothesized that the activity of amonafide L-malate in S-AML may be attributable in part to its being a poor substrate for the multidrug resistance (MDR)-associated drug efflux proteins expressed in AML cells, including P-glycoprotein (Pgp; MDR1; ABCB1), multidrug resistance protein-1 (MRP-1;ABCC1) and breast cancer resistance protein (BCRP;ABCG2). Amonafide has been previously shown not to be a substrate for Pgp in cell lines overexpressing this protein (Chau, et al., Leuk Res, in press). Here we studied transport and cytotoxicity of amonafide L-malate and its active metabolite N-acetyl amonafide in cell lines overexpressing Pgp, MRP-1 and BCRP and in pretreatment blasts from patients with S-AML. Cellular drug transport was studied by flow cytometry and cytotoxicity was studied in 96-well microcultures in the absence and presence of the MDR modulators PSC-833 (Pgp), probenecid (MRP-1) and fumitremorgin C (FTC), and were compared with those of classical topoisomerase 2 inhibitors including doxorubicin, daunorubicin, idarubicin, mitoxantrone and etoposide in leukemia and myeloma cell lines overexpressing Pgp, MRP-1 and BCRP and in pretreatment marrow samples from 22 S-AML patients characterized with regard to expression and function of these proteins. S-AML patients included 9 with therapy-related AML and 13 with antecedent myelodysplastic syndromes. Pgp, MRP-1 and BCRP expression in pretreatment blasts was measured by flow cytometry with the MRK16, MRPm6 and BXP21 antibodies, and function by uptake of the fluorescent substrates DiOC2(3), rhodamine-123 and pheophorbide A with modulation by PSC-833, probenecid and FTC, respectively. Uptake, efflux and cytotoxicity of amonafide L-malate did not differ in resistant cell lines overexpressing Pgp, MRP-1 and BCRP, compared to parental cells, and did not differ in the presence and absence of MDR modulators, in contrast to all of the other topoisomerase 2 inhibitors studied. Cell lines overexpressing Pgp and MRP-1 did not display transport of, or resistance to, the metabolite, acetyl amonafide, but acetyl amonafide was a substrate for BCRP, with 8-fold resistance in cells with BCRP expression, and 8-fold sensitization by FTC. Pgp, MRP-1 and BCRP expression and/or function was observed in 18, 7 and 17 of 22 secondary AML samples, respectively. Cyclosporin A, which inhibits substrate drug efflux by Pgp, MRP-1 and BCRP, increased uptake of daunorubicin, idarubicin and amonafide L-malate by mean values of 19.7%, 7% and −2.5%, respectively, and increased uptake by ≥ 10% in 16, 12 and 5 patient samples. In conclusion, in relation to other topoisomerase 2 inhibitors used to treat AML, including daunorubicin, idarubicin, mitoxantrone, and etoposide, amonafide L-malate is a poor substrate for the MDR proteins expressed in AML cells in general, and S-AML cells in particular. The encouraging complete remission rates seen with amonafide L-malate treatment in clinical trials in S-AML may thus be attributed at least in part to its potential to overcome MDR in S-AML cells.

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39

Yamaguchi, Junji, Hitoshi Mori, and Mikio Nishimura. "Biosynthesis and intracellular transport of glyoxysomal malate dehydrogenase in germinating pumpkin cotyledons." FEBS Letters 213, no. 2 (March 23, 1987): 329–32. http://dx.doi.org/10.1016/0014-5793(87)81516-8.

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40

Herzberger, E., and F. Radler. "How hexoses and inhibitors influence the malate transport system in Zygosaccharomyces bailii." Archives of Microbiology 150, no. 1 (May 1988): 37–41. http://dx.doi.org/10.1007/bf00409715.

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41

Miniero, Daniela Valeria, Nicola Gambacorta, Anna Spagnoletta, Vincenzo Tragni, Stefano Loizzo, Orazio Nicolotti, Ciro Leonardo Pierri, and Annalisa De Palma. "New Insights Regarding Hemin Inhibition of the Purified Rat Brain 2-Oxoglutarate Carrier and Relationships with Mitochondrial Dysfunction." Journal of Clinical Medicine 11, no. 24 (December 19, 2022): 7519. http://dx.doi.org/10.3390/jcm11247519.

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A kinetic analysis of the transport assays on the purified rat brain 2-oxoglutarate/malate carrier (OGC) was performed starting from our recent results reporting about a competitive inhibitory behavior of hemin, a physiological porphyrin derivative, on the OGC reconstituted in an active form into proteoliposomes. The newly provided transport data and the elaboration of the kinetic equations show evidence that hemin exerts a mechanism of partially competitive inhibition, coupled with the formation of a ternary complex hemin-carrier substrate, when hemin targets the OGC from the matrix face. A possible interpretation of the provided kinetic analysis, which is supported by computational studies, could indicate the existence of a binding region responsible for the inhibition of the OGC and supposedly involved in the regulation of OGC activity. The proposed regulatory binding site is located on OGC mitochondrial matrix loops, where hemin could establish specific interactions with residues involved in the substrate recognition and/or conformational changes responsible for the translocation of mitochondrial carrier substrates. The regulatory binding site would be placed about 6 Å below the substrate binding site of the OGC, facing the mitochondrial matrix, and would allow the simultaneous binding of hemin and 2-oxoglutarate or malate to different regions of the carrier. Overall, the presented experimental and computational analyses help to shed light on the possible existence of the hemin-carrier substrate ternary complex, confirming the ability of the OGC to bind porphyrin derivatives, and in particular hemin, with possible consequences for the mitochondrial redox state mediated by the malate/aspartate shuttle led by the mitochondrial carriers OGC and AGC.

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42

Thome, Trace, Zachary R. Salyers, Ravi A. Kumar, Dongwoo Hahn, Fabian N. Berru, Leonardo F. Ferreira, Salvatore T. Scali, and Terence E. Ryan. "Uremic metabolites impair skeletal muscle mitochondrial energetics through disruption of the electron transport system and matrix dehydrogenase activity." American Journal of Physiology-Cell Physiology 317, no. 4 (October 1, 2019): C701—C713. http://dx.doi.org/10.1152/ajpcell.00098.2019.

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Chronic kidney disease (CKD) leads to increased skeletal muscle fatigue, weakness, and atrophy. Previous work has implicated mitochondria within the skeletal muscle as a mediator of muscle dysfunction in CKD; however, the mechanisms underlying mitochondrial dysfunction in CKD are not entirely known. The purpose of this study was to define the impact of uremic metabolites on mitochondrial energetics. Skeletal muscle mitochondria were isolated from C57BL/6N mice and exposed to vehicle (DMSO) or varying concentrations of uremic metabolites: indoxyl sulfate, indole-3-acetic-acid, l-kynurenine, and kynurenic acid. A comprehensive mitochondrial phenotyping platform that included assessments of mitochondrial oxidative phosphorylation (OXPHOS) conductance and respiratory capacity, hydrogen peroxide production ( JH2O2), matrix dehydrogenase activity, electron transport system enzyme activity, and ATP synthase activity was employed. Uremic metabolite exposure resulted in a ~25–40% decrease in OXPHOS conductance across multiple substrate conditions ( P < 0.05, n = 5–6/condition), as well as decreased ADP-stimulated and uncoupled respiratory capacity. ATP synthase activity was not impacted by uremic metabolites; however, a screen of matrix dehydrogenases indicated that malate and glutamate dehydrogenases were impaired by some, but not all, uremic metabolites. Assessments of electron transport system enzymes indicated that uremic metabolites significantly impair complex III and IV. Uremic metabolites resulted in increased JH2O2 under glutamate/malate, pyruvate/malate, and succinate conditions across multiple levels of energy demand (all P < 0.05, n = 4/group). Disruption of mitochondrial OXPHOS was confirmed by decreased respiratory capacity and elevated superoxide production in cultured myotubes. These findings provide direct evidence that uremic metabolites negatively impact skeletal muscle mitochondrial energetics, resulting in decreased energy transfer, impaired complex III and IV enzyme activity, and elevated oxidant production.

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43

Ullmann, Roland, Roland Gross, Jörg Simon, Gottfried Unden, and Achim Kröger. "Transport of C4-Dicarboxylates inWolinella succinogenes." Journal of Bacteriology 182, no. 20 (October 15, 2000): 5757–64. http://dx.doi.org/10.1128/jb.182.20.5757-5764.2000.

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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.

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44

Dantzler, W. H., and K. K. Evans. "Effect of alpha-KG in lumen on PAH transport by isolated perfused rabbit renal proximal tubules." American Journal of Physiology-Renal Physiology 271, no. 3 (September 1, 1996): F521—F526. http://dx.doi.org/10.1152/ajprenal.1996.271.3.f521.

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To determine whether dicarboxylate taken up at the luminal membrane could function in the p-aminohippurate (PAH) countertransport at the basolateral membrane, we examined the effect of adding alpha-ketoglutarate (alpha-KG) or glutarate (a nonmetabolized dicarboxylate that is countertransported for PAH at the basolateral membrane) to the luminal perfusate on net secretion of radiolabeled PAH in isolated perfused S2 segments of rabbit proximal tubules. Addition of 100 microM alpha-KG or glutarate to the luminal perfusate in tubules perfused and bathed with HEPES-buffered medium (in the absence of bicarbonate, glycine, lactate, malate, and citrate) produced a reversible twofold stimulation of net PAH transepithelial secretion. Addition of 4 mM LiCl (an inhibitor of Na-dicarboxylate transport that does not directly affect PAH transport) to the luminal perfusate along with alpha-KG eliminated stimulation of net PAH secretion. Addition of 100 microM or 1 mM alpha-KG or glutarate to the luminal perfusate in tubules perfused and bathed with bicarbonate-buffered medium containing glycine, lactate, malate, and citrate had no effect on net PAH transport from bath to lumen. These data indicate that alpha-KG (or glutarate) that enters the tubule cells via the luminal Na-dicarboxylate cotransporter can stimulate net PAH secretion, apparently via countertransport at the basolateral membrane, but only when tubules are not in an optimal metabolic state to produce intracellular alpha-KG.

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Singh, Vijay Shankar, Prajna Tripathi, Parul Pandey, Durgesh Narain Singh, Basant Kumar Dubey, Chhaya Singh, Surendra Pratap Singh, Rachana Pandey, and Anil Kumar Tripathi. "Dicarboxylate Transporters of Azospirillum brasilense Sp7 Play an Important Role in the Colonization of Finger Millet (Eleusine coracana) Roots." Molecular Plant-Microbe Interactions® 32, no. 7 (July 2019): 828–40. http://dx.doi.org/10.1094/mpmi-12-18-0344-r.

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Azospirillum brasilense is a plant growth–promoting bacterium that colonizes the roots of a large number of plants, including C3 and C4 grasses. Malate has been used as a preferred source of carbon for the enrichment and isolation Azospirillum spp., but the genes involved in their transport and utilization are not yet characterized. In this study, we investigated the role of the two types of dicarboxylate transporters (DctP and DctA) of A. brasilense in their ability to colonize and promote growth of the roots of a C4 grass. We found that DctP protein was distinctly upregulated in A. brasilense grown with malate as sole carbon source. Inactivation of dctP in A. brasilense led to a drastic reduction in its ability to grow on dicarboxylates and form cell aggregates. Inactivation of dctA, however, showed a marginal reduction in growth and flocculation. The growth and nitrogen fixation of a dctP and dctA double mutant of A. brasilense were severely compromised. We have shown here that DctPQM and DctA transporters play a major and a minor role in the transport of C4-dicarboxylates in A. brasilense, respectively. Studies on inoculation of the seedlings of a C4 grass, Eleusine corcana, with A. brasilense and its dicarboxylate transport mutants revealed that dicarboxylate transporters are required by A. brasilense for an efficient colonization of plant roots and their growth.

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Hassel, Bjørnar, Anders Bråthe, and Dirk Petersen. "Cerebral dicarboxylate transport and metabolism studied with isotopically labelled fumarate, malate and malonate." Journal of Neurochemistry 82, no. 2 (July 3, 2002): 410–19. http://dx.doi.org/10.1046/j.1471-4159.2002.00986.x.

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47

Heng, Yueqin, Chuanyin Wu, Yu Long, Sheng Luo, Jin Ma, Jun Chen, Jiafan Liu, et al. "OsALMT7 Maintains Panicle Size and Grain Yield in Rice by Mediating Malate Transport." Plant Cell 30, no. 4 (April 2018): 889–906. http://dx.doi.org/10.1105/tpc.17.00998.

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48

Martinoia, Enrico, Esther Vogt, and Nikolaus Amrhein. "Transport of malate and chloride into barley mesophyll vacuoles Different carriers are involved." FEBS Letters 261, no. 1 (February 12, 1990): 109–11. http://dx.doi.org/10.1016/0014-5793(90)80648-3.

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Tourdot-Marechal, R., P. Chamaret, J. F. Cavin, and C. Davies. "Obtaining functional membrane vesicles from Leuconostoc oenos to study l-malate transport mechanisms." Applied Microbiology and Biotechnology 41, no. 5 (July 1994): 603–7. http://dx.doi.org/10.1007/bf00178497.

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50

Vázquez-Martínez, Olivia, Mauricio Díaz-Muñoz, Fernando López-Barrera, and Rolando Hernández-Muñoz. "Mitochondrial Oxidation of the Cytoplasmic Reducing Equivalents at the Onset of Oxidant Stress in the Isoproterenol-Induced Rat Myocardial Infarction." Antioxidants 10, no. 9 (September 11, 2021): 1444. http://dx.doi.org/10.3390/antiox10091444.

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We have developed and characterized a model of isoproterenol (ISO)-induced myocardial necrosis, identifying three stages of cardiac damage: a pre-infarction (0–12 h), infarction (24 h), and post-infarction period (48–96 h). Using this model, we have previously found alterations in calcium homeostasis and their relationship with oxidant stress in mitochondria, which showed deficient oxygen consumption and coupled ATP synthesis. Therefore, the present study was aimed at assessing the mitochondrial ability to transport and oxidize cytoplasmic reducing equivalents (NADH), correlating the kinetic parameters of the malate-aspartate shuttle, oxidant stress, and mitochondrial functionality. Our results showed only discreet effects during the cardiotoxic ISO action on the endogenous malate-aspartate shuttle activity, suggesting that endogenous mitochondrial NADH oxidation capacity (Nohl dehydrogenase) was not affected by the cellular stress. On the contrary, the reconstituted system showed significant enhancement in maximal capacity of the malate-aspartate shuttle activity only at later times (post-infarction period), probably as a compensatory part of cardiomyocytes’ response to the metabolic and functional consequences of the infarcted tissue. Therefore, these findings support the notion that heart damage associated with myocardial infarction suffers a set of sequential biochemical and metabolic modifications within cardiomyocytes, where mitochondrial activity, controlling the redox state, could play a relevant role.

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