Regulation of the TCA cycle and the general amino acid permease by overflow metabolism in Rhizobium leguminosarum

ABSTRACT Amino acid uptake by Rhizobium leguminosarum is dominated by two ABC transporters, the general amino acid permease (Aap) and the branched-chain amino acid permease (BraRl). Characterization of the solute specificity of BraRl shows it to be the second general amino acid permease of R. leguminosarum. Although BraRl has high sequence identity to members of the family of hydrophobic amino acid transporters (HAAT), it transports a broad range of solutes, including acidic and basic polar amino acids (l-glutamate, l-arginine, and l-histidine), in addition to neutral amino acids (l-alanine and l-leucine). While amino and carboxyl groups are required for transport, solutes do not have to be α-amino acids. Consistent with this, BraRl is the first ABC transporter to be shown to transport γ-aminobutyric acid (GABA). All previously identified bacterial GABA transporters are secondary carriers of the amino acid-polyamine-organocation (APC) superfamily. Also, transport by BraRl does not appear to be stereospecific as d amino acids cause significant inhibition of uptake of l-glutamate and l-leucine. Unlike all other solutes tested, l-alanine uptake is not dependent on solute binding protein BraCRl. Therefore, a second, unidentified solute binding protein may interact with the BraDEFGRl membrane complex during l-alanine uptake. Overall, the data indicate that BraRl is a general amino acid permease of the HAAT family. Furthermore, BraRl has the broadest solute specificity of any characterized bacterial amino acid transporter.

Download Full-text

The general amino acid permease of Rhizobium leguminosarum strain 3841 is negatively regulated by the Ntr system

FEMS Microbiology Letters ◽

10.1111/j.1574-6968.1997.tb10409.x ◽

2006 ◽

Vol 152 (1) ◽

pp. 57-64 ◽

Cited By ~ 9

Author(s):

David L Walshaw ◽

Colm J Reid ◽

Philip S Poole

Keyword(s):

Amino Acid ◽

Rhizobium Leguminosarum ◽

Amino Acid Permease ◽

General Amino Acid Permease

Download Full-text

Faculty Opinions recommendation of A conserved GTPase-containing complex is required for intracellular sorting of the general amino-acid permease in yeast.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1040377.489550 ◽

2006 ◽

Author(s):

Ruth Collins

Keyword(s):

Amino Acid ◽

Amino Acid Permease ◽

General Amino Acid Permease ◽

Intracellular Sorting

Download Full-text

Ammonia regulation of amino acid permeases in Saccharomyces cerevisiae

Molecular and Cellular Biology ◽

10.1128/mcb.3.4.672-683.1983 ◽

1983 ◽

Vol 3 (4) ◽

pp. 672-683

Author(s):

W E Courchesne ◽

B Magasanik

Keyword(s):

Saccharomyces Cerevisiae ◽

Amino Acid ◽

Cytoplasmic Membrane ◽

Nitrogen Sources ◽

Amino Acid Permease ◽

Inducer Exclusion ◽

Amino Acid Permeases ◽

General Amino Acid Permease ◽

State Growth ◽

And Control

The activities of the proline-specific permease (PUT4) and the general amino acid permease (GAP1) of Saccharomyces cerevisiae vary 70- to 140-fold in response to the nitrogen source of the growth medium. The PUT4 and GAP1 permease activities are regulated by control of synthesis and control of activity. These permeases are irreversibly inactivated by addition of ammonia or glutamine, lowering the activity to that found during steady-state growth on these nitrogen sources. Mutants altered in the regulation of the PUT4 permease (Per-) have been isolated. The mutations in these strains are pleiotropic and affect many other permeases, but have no direct effect on various cytoplasmic enzymes involved in nitrogen assimilation. In strains having one class of mutations (per1), ammonia inactivation of the PUT4 and GAP1 permeases did not occur, whereas glutamate and glutamine inactivation did. Thus, there appear to be two independent inactivation systems, one responding to ammonia and one responding to glutamate (or a metabolite of glutamate). The mutations were found to be nuclear and recessive. The inactivation systems are constitutive and do not require transport of the effector molecules per se, apparently operating on the inside of the cytoplasmic membrane. The ammonia inactivation was found not to require a functional glutamate dehydrogenase (NADP). These mutants were used to show that ammonia exerts control of arginase synthesis largely by inducer exclusion. This may be the primary mode of nitrogen regulation for most nitrogen-regulated enzymes of S. cerevisiae.

Download Full-text

Disruption of the TCA cycle reveals an ATF4-dependent integration of redox and amino acid metabolism

eLife ◽

10.7554/elife.72593 ◽

2021 ◽

Vol 10 ◽

Author(s):

Dylan Gerard Ryan ◽

Ming Yang ◽

Hiran A Prag ◽

Giovanny Rodriguez Blanco ◽

Efterpi Nikitopoulou ◽

...

Keyword(s):

Amino Acid ◽

Amino Acid Metabolism ◽

Acid Metabolism ◽

Metabolic Response ◽

Tricarboxylic Acid Cycle ◽

Fumarate Hydratase ◽

Tca Cycle ◽

Comparative Approach ◽

Redox Biology ◽

The Tca Cycle

The Tricarboxylic Acid Cycle (TCA) cycle is arguably the most critical metabolic cycle in physiology and exists as an essential interface coordinating cellular metabolism, bioenergetics, and redox homeostasis. Despite decades of research, a comprehensive investigation into the consequences of TCA cycle dysfunction remains elusive. Here, we targeted two TCA cycle enzymes, fumarate hydratase (FH) and succinate dehydrogenase (SDH), and combined metabolomics, transcriptomics, and proteomics analyses to fully appraise the consequences of TCA cycle inhibition (TCAi) in murine kidney epithelial cells. Our comparative approach shows that TCAi elicits a convergent rewiring of redox and amino acid metabolism dependent on the activation of ATF4 and the integrated stress response (ISR). Furthermore, we also uncover a divergent metabolic response, whereby acute FHi, but not SDHi, can maintain asparagine levels via reductive carboxylation and maintenance of cytosolic aspartate synthesis. Our work highlights an important interplay between the TCA cycle, redox biology and amino acid homeostasis.

Download Full-text

Relief from nitrogen starvation entails quick unexpected down-regulation of glycolytic/lipid metabolism genes in enologicalSaccharomyces cerevisiae

10.1101/428979 ◽

2018 ◽

Author(s):

Tesnière Catherine ◽

Bessière Chloé ◽

Pradal Martine ◽

Sanchez Isabelle ◽

Blondin Bruno ◽

...

Keyword(s):

Lipid Metabolism ◽

Amino Acid ◽

Wine Yeast ◽

Tca Cycle ◽

Nitrogen Addition ◽

White Wine ◽

Ammonium Nitrogen ◽

Ribosomal Protein Genes ◽

Amino Acid Permease ◽

Transcriptional Responses

AbstractNitrogen composition of the grape must has an impact on yeast growth and fermentation kinetics as well as on the organoleptic properties of the final product. In some technological processes, such as white wine/rosé winemaking, the yeast-assimilable nitrogen content is sometimes insufficient to cover yeast requirements, which can lead to slow or sluggish fermentations. Growth is nevertheless quickly restored upon relief from nutrient starvation, e.g. through the addition of ammonium nitrogen, allowing fermentation completion. The aim of this study was to determine how nitrogen repletion affected the transcriptional response of aSaccharomyces cerevisiaewine yeast strain, in particular within the first hour after nitrogen addition. We found almost 4800 genes induced or repressed, sometimes within minutes after nutrient changes. Some of these responses to nitrogen depended on the TOR pathway, which controls positively ribosomal protein genes, amino acid and purine biosynthesis or amino acid permease genes and negatively stress-response genes, and genes related to the retrograde response (RTG) specific to the tricarboxylic acid (TCA) cycle and nitrogen catabolite repression (NCR). Some unexpected transcriptional responses concerned all the glycolytic genes, carbohydrate metabolism and TCA cycle-related genes that were down-regulated, as well as genes from the lipid metabolism.

Download Full-text

P207 Synergetic effect of amino acid and ketone metabolism underlies empagliflozin-mediated cardioprotection in the type 2 diabetic heart

European Heart Journal ◽

10.1093/ehjci/ehz872.077 ◽

2020 ◽

Vol 41 (Supplement_1) ◽

Author(s):

H Kouzu ◽

H Oshima ◽

T Miki ◽

A Kuno ◽

T Sato ◽

...

Keyword(s):

Amino Acid ◽

Survival Rate ◽

Molecular Mechanisms ◽

Synergetic Effect ◽

Tca Cycle ◽

Oxidative Capacity ◽

Metabolome Analysis ◽

Coa Transferase ◽

The Tca Cycle

Abstract Funding Acknowledgements Boehringer Ingelheim Background Although emerging evidence has indicated that sodium glucose cotransporter 2 (SGLT2) inhibitors restore impaired cardiac energetics in type 2 diabetes mellitus (T2DM), the underlying molecular mechanisms have yet to be established. Augmented utilization of ketone is one proposed hypothesis, but depletion of succinyl-CoA triggered by the conversion of ketone back to acetyl-CoA by SCOT (succinyl-CoA:3-oxoacid CoA transferase) may hamper oxidative capacity of the tricarboxylic acid (TCA) cycle, which also requires succinyl-CoA. The recent finding that empagliflozin augments systemic amino acid metabolism in patients with T2DM led us to hypothesize that the anaplerotic effect of amino acid on the TCA cycle complements ketone oxidation. Methods and Results Myocardial infarction (MI) was induced in T2DM rats (OLETF) and control rats (LETO). Survival rate at 48 hours after MI was significantly lower in OLETF than in LETO (40% vs 84%), and empagliflozin treatment (10 mg/kg/day, 14 days) before MI improved the survival rate in OLETF to 70%. Metabolome analysis was performed using heart tissues from the non-infarct region 12 hours after MI. Using principal component analysis, data from 92 metabolites that were detected were compressed into 2 dimensions, and the first component (PC1) clearly separated empagliflozin-treated OLETF from non-treated LETO and OLETF. Analysis of factor loading of each metabolite for PC1 revealed that branched chain amino acids leucine, isoleucine and valine, the latter two of which can be oxidized to succynyl-CoA, and β-hydroxybutyrate were the top four metabolites that characterized empagliflozin treatment. Furthermore, in comparison to LETO, OLETF treated with empagliflozin showed 50% higher levels of glutamine and glutamate, both of which can replenish the TCA cycle at the level of α-ketoglutarate. In OLETF, empagliflozin significantly increased the TCA cycle intermediates citrate, cis-aconitate and malate by 74%, 119% and 59%, respectively. OLETF showed 86% higher lactate and 38% lower ATP than those in LETO, but levels of the metabolites were normalized by empagliflozin, suggesting improved glucose oxidation. Conclusions The present analyses showed that amino acid and ketone metabolism are metabolic pathways that are most affected by empagliflozin. Coordination of these "starvation-induced pathways" may underlie the favorable metabolic effect of empagliflozin in T2DM hearts.

Download Full-text

Regulation of acetate metabolism and coordination with the TCA cycle via a processed small RNA

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1815288116 ◽

2018 ◽

Vol 116 (3) ◽

pp. 1043-1052 ◽

Cited By ~ 16

Author(s):

François De Mets ◽

Laurence Van Melderen ◽

Susan Gottesman

Keyword(s):

Small Rna ◽

Posttranscriptional Regulation ◽

Tca Cycle ◽

Central Carbon Metabolism ◽

Growth Defect ◽

Acetate Metabolism ◽

Overflow Metabolism ◽

Acetyl Phosphate ◽

Rnase E ◽

The Tca Cycle

Bacterial regulatory small RNAs act as crucial regulators in central carbon metabolism by modulating translation initiation and degradation of target mRNAs in metabolic pathways. Here, we demonstrate that a noncoding small RNA, SdhX, is produced by RNase E-dependent processing from the 3′UTR of thesdhCDAB-sucABCDoperon, encoding enzymes of the tricarboxylic acid (TCA) cycle. InEscherichia coli, SdhX negatively regulatesackA, which encodes an enzyme critical for degradation of the signaling molecule acetyl phosphate, while the downstreamptagene, encoding the enzyme critical for acetyl phosphate synthesis, is not significantly affected. This discoordinate regulation ofptaandackAincreases the accumulation of acetyl phosphate when SdhX is expressed. Mutations insdhXthat abolish regulation ofackAlead to more acetate in the medium (more overflow metabolism), as well as a strong growth defect in the presence of acetate as sole carbon source, when the AckA-Pta pathway runs in reverse. SdhX overproduction confers resistance to hydroxyurea, via regulation ofackA. SdhX abundance is tightly coupled to the transcription signals of TCA cycle genes but escapes all known posttranscriptional regulation. Therefore, SdhX expression directly correlates with transcriptional input to the TCA cycle, providing an effective mechanism for the cell to link the TCA cycle with acetate metabolism pathways.

Download Full-text