1
|
Mochizuki K, Inaoka DK, Mazet M, Shiba T, Fukuda K, Kurasawa H, Millerioux Y, Boshart M, Balogun EO, Harada S, Hirayama K, Bringaud F, Kita K. The ASCT/SCS cycle fuels mitochondrial ATP and acetate production in Trypanosoma brucei. Biochim Biophys Acta Bioenerg 2020; 1861:148283. [PMID: 32763239 PMCID: PMC7402102 DOI: 10.1016/j.bbabio.2020.148283] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/22/2020] [Accepted: 07/29/2020] [Indexed: 11/03/2022]
Abstract
Acetate:succinate CoA transferase (ASCT) is a mitochondrial enzyme that catalyzes the production of acetate and succinyl-CoA, which is coupled to ATP production with succinyl-CoA synthetase (SCS) in a process called the ASCT/SCS cycle. This cycle has been studied in Trypanosoma brucei (T. brucei), a pathogen of African sleeping sickness, and is involved in (i) ATP and (ii) acetate production and proceeds independent of oxygen and an electrochemical gradient. Interestingly, knockout of ASCT in procyclic form (PCF) of T. brucei cause oligomycin A-hypersensitivity phenotype indicating that ASCT/SCS cycle complements the deficiency of ATP synthase activity. In bloodstream form (BSF) of T. brucei, ATP synthase works in reverse to maintain the electrochemical gradient by hydrolyzing ATP. However, no information has been available on the source of ATP, although ASCT/SCS cycle could be a potential candidate. Regarding mitochondrial acetate production, which is essential for fatty acid biosynthesis and growth of T. brucei, ASCT or acetyl-CoA hydrolase (ACH) are known to be its source. Despite the importance of this cycle, direct evidence of its function is lacking, and there are no comprehensive biochemical or structural biology studies reported so far. Here, we show that in vitro–reconstituted ASCT/SCS cycle is highly specific towards acetyl-CoA and has a higher kcat than that of yeast and bacterial ATP synthases. Our results provide the first biochemical basis for (i) rescue of ATP synthase-deficient phenotype by ASCT/SCS cycle in PCF and (ii) a potential source of ATP for the reverse reaction of ATP synthase in BSF. First biochemical and structural characterization of mitochondrial ASCT/SCS cycle It is essential for mitochondrial acetate/ATP production and T. brucei BSF growth. TbASCT/SCS cycle shows higher kcat than that of yeast and bacterial ATP synthases. Detailed comparative biochemical analysis between ASCT and human SCOT Active site residue and X-CoA binding site determined by site-directed mutagenesis
Collapse
Affiliation(s)
- Kota Mochizuki
- Department of Immunogenetics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Japan; Graduate School of Biomedical Sciences, Nagasaki University, Japan
| | - Daniel Ken Inaoka
- Department of Molecular Infection Dynamics, Shionogi Global Infectious Diseases Division, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Japan; School of Tropical Medicine and Global Health, Nagasaki University, Japan; Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Japan.
| | - Muriel Mazet
- Laboratoire de Microbiologie Fondamentale et Pathogénicité (MFP), Université de Bordeaux, CNRS UMR-5234, France
| | - Tomoo Shiba
- Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Japan.
| | - Keisuke Fukuda
- Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Japan
| | - Hana Kurasawa
- Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Japan
| | - Yoann Millerioux
- Laboratoire de Microbiologie Fondamentale et Pathogénicité (MFP), Université de Bordeaux, CNRS UMR-5234, France
| | - Michael Boshart
- Fakultät für Biologie, Genetik, Ludwig-Maximilians-Universität München, Germany
| | - Emmanuel O Balogun
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Japan; Department of Biochemistry, Ahmadu Bello University, Nigeria
| | - Shigeharu Harada
- Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Japan
| | - Kenji Hirayama
- Department of Immunogenetics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Japan
| | - Frédéric Bringaud
- Laboratoire de Microbiologie Fondamentale et Pathogénicité (MFP), Université de Bordeaux, CNRS UMR-5234, France
| | - Kiyoshi Kita
- School of Tropical Medicine and Global Health, Nagasaki University, Japan; Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Japan; Department of Host - Defense Biochemistry, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Japan
| |
Collapse
|
2
|
Chinopoulos C. Acute sources of mitochondrial NAD + during respiratory chain dysfunction. Exp Neurol 2020; 327:113218. [PMID: 32035071 DOI: 10.1016/j.expneurol.2020.113218] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/24/2020] [Accepted: 01/30/2020] [Indexed: 01/07/2023]
Abstract
It is a textbook definition that in the absence of oxygen or inhibition of the mitochondrial respiratory chain by pharmacologic or genetic means, hyper-reduction of the matrix pyridine nucleotide pool ensues due to impairment of complex I oxidizing NADH, leading to reductive stress. However, even under these conditions, the ketoglutarate dehydrogenase complex (KGDHC) is known to provide succinyl-CoA to succinyl-CoA ligase, thus supporting mitochondrial substrate-level phosphorylation (mSLP). Mindful that KGDHC is dependent on provision of NAD+, hereby sources of acute NADH oxidation are reviewed, namely i) mitochondrial diaphorases, ii) reversal of mitochondrial malate dehydrogenase, iii) reversal of the mitochondrial isocitrate dehydrogenase as it occurs under acidic conditions, iv) residual complex I activity and v) reverse operation of the malate-aspartate shuttle. The concept of NAD+ import through the inner mitochondrial membrane as well as artificial means of manipulating matrix NAD+/NADH are also discussed. Understanding the above mechanisms providing NAD+ to KGDHC thus supporting mSLP may assist in dampening mitochondrial dysfunction underlying neurological disorders encompassing impairment of the electron transport chain.
Collapse
Affiliation(s)
- Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest 1094, Hungary.
| |
Collapse
|
3
|
Abstract
During tissue ischemia succinate accumulates. Herein, literature spanning the past nine decades is reviewed leaning towards the far greater role of Krebs cycle's canonical activity yielding succinate through α-ketoglutarate -> succinyl-CoA -> succinate even in hypoxia, as opposed to reversal of succinate dehydrogenase. Furthermore, the concepts of i) a diode-like property of succinate dehydrogenase rendering it difficult to reverse, and ii) the absence of mammalian mitochondrial quinones exhibiting redox potentials in the [-60, -80] mV range needed for fumarate reduction, are discussed. Finally, it is emphasized that a "fumarate reductase" enzyme entity reducing fumarate to succinate found in some bacteria and lower eukaryotes remains to be discovered in mammalian mitochondria.
Collapse
Affiliation(s)
- Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Tuzolto st. 37-47, Budapest, 1094, Hungary.
| |
Collapse
|
4
|
Li SL, Yen JH, Kano K, Liu SM, Liu CL, Cheng SS, Chen HY. Using metabolic charge production in the tricarboxylic acid cycle (Q TCA) to evaluate the extracellular-electron-transfer performances of Shewanella spp. Bioelectrochemistry 2018; 124:119-26. [PMID: 30015268 DOI: 10.1016/j.bioelechem.2018.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 06/24/2018] [Accepted: 07/03/2018] [Indexed: 01/13/2023]
Abstract
Using an electrochemical cell equipped with carbon felt electrodes (poised at +0.63 V vs. SHE), the current production capabilities of two Shewanella strains-NTOU1 and KR-12-were examined under various conditions with lactate as an electron donor. The metabolic charge produced in the tricarboxylic acid cycle (QTCA) was calculated by mass-balance. The data showed a linear relation between the electric coulomb production (QEL) and QTCA with an R2 of 0.65. In addition, a large amount of pyruvate accumulation was observed at pH = 6, rendering QTCA negative. The results indicate an occurrence of an undesired cataplerotic reaction. It was also found that QTCA provides important information showing the oxygen-boosting TCA cycle and anodic-current generation of Shewanella spp. Linear dependence of the change in charge for biomass growth (4.52FΔnCell) on QTCA was also found as expressed by 4.52FΔnCell = 1.0428 QTCA + 0.0442, indicating that these two charge quantities are inherently identical under most of the experimental conditions. In the mediator-spiked experiments, the external addition of the mediators (ferricyanide, anthraquinone-2, 6-disulfonate, and riboflavin) beyond certain concentrations inhibited the activity of the TCA cycle, indicating that the oxidative phosphorylation is deactivated by excessive amounts of mediators, yet Shewanella spp. are constrained with regard to carrying out the substrate-level phosphorylation.
Collapse
|
5
|
Komlódi T, Tretter L. Methylene blue stimulates substrate-level phosphorylation catalysed by succinyl-CoA ligase in the citric acid cycle. Neuropharmacology 2017; 123:287-298. [PMID: 28495375 DOI: 10.1016/j.neuropharm.2017.05.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 05/05/2017] [Accepted: 05/07/2017] [Indexed: 10/19/2022]
Abstract
Methylene blue (MB), a potential neuroprotective agent, is efficient in various neurodegenerative disease models. Beneficial effects of MB have been attributed to improvements in mitochondrial functions. Substrate-level phosphorylation (SLP) results in the production of ATP independent from the ATP synthase (ATP-ase). In energetically compromised mitochondria, ATP produced by SLP can prevent the reversal of the adenine nucleotide translocase and thus the hydrolysis of glycolytic ATP. The aim of the present study was to investigate the effect of MB on mitochondrial SLP catalysed by succinyl-CoA ligase. Measurements were carried out on isolated guinea pig cortical mitochondria respiring on α-ketoglutarate, glutamate, malate or succinate. The mitochondrial functions and parameters like ATP synthesis, oxygen consumption, membrane potential, and NAD(P)H level were followed online, in parallel with the redox state of MB. SLP-mediated ATP synthesis was measured in the presence of inhibitors for ATP-ase and adenylate kinase. In the presence of the ATP-ase inhibitor oligomycin MB stimulated respiration with all of the respiratory substrates. However, the rate of ATP synthesis increased only with substrates α-ketoglutarate and glutamate (forming succinyl-CoA). MB efficiently stimulated SLP and restored the membrane potential in mitochondria also with the combined inhibition of Complex I and ATP synthase. ATP formed by SLP alleviated the energetic insufficiency generated by the lack of oxidative phosphorylation. Thus, the MB-mediated stimulation of SLP might be important in maintaining the energetic competence of mitochondria and in preventing the mitochondrial hydrolysis of glycolytic ATP. The mitochondrial effects of MB are explained by the ability to accept electrons from reducing equivalents and transfer them to cytochrome c bypassing the respiratory Complexes I and III.
Collapse
Affiliation(s)
- T Komlódi
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto St., Budapest, 1094, Hungary
| | - L Tretter
- Department of Medical Biochemistry, MTA-SE Laboratory for Neurobiochemistry, Semmelweis University, 37-47 Tuzolto St., Budapest, 1094, Hungary.
| |
Collapse
|
6
|
Tretter L, Patocs A, Chinopoulos C. Succinate, an intermediate in metabolism, signal transduction, ROS, hypoxia, and tumorigenesis. Biochim Biophys Acta 2016; 1857:1086-101. [PMID: 26971832 DOI: 10.1016/j.bbabio.2016.03.012] [Citation(s) in RCA: 309] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/06/2016] [Accepted: 03/07/2016] [Indexed: 12/31/2022]
Abstract
Succinate is an important metabolite at the cross-road of several metabolic pathways, also involved in the formation and elimination of reactive oxygen species. However, it is becoming increasingly apparent that its realm extends to epigenetics, tumorigenesis, signal transduction, endo- and paracrine modulation and inflammation. Here we review the pathways encompassing succinate as a metabolite or a signal and how these may interact in normal and pathological conditions.(1).
Collapse
|