scholarly journals ANT1 Activation and Inhibition Patterns Support the Fatty Acid Cycling Mechanism for Proton Transport

2021 ◽  
Vol 22 (5) ◽  
pp. 2490
Author(s):  
Jürgen Kreiter ◽  
Anne Rupprecht ◽  
Sanja Škulj ◽  
Zlatko Brkljača ◽  
Kristina Žuna ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Lipid Bilayers ◽  
Proton Transport ◽  
Mitochondrial Membrane ◽  
Adenine Nucleotide ◽  
Molecular Transport ◽  
Correlation Spectroscopy ◽  
Dual Function ◽  
Inner Mitochondrial Membrane ◽  
Purine Nucleotides

Adenine nucleotide translocase (ANT) is a well-known mitochondrial exchanger of ATP against ADP. In contrast, few studies have shown that ANT also mediates proton transport across the inner mitochondrial membrane. The results of these studies are controversial and lead to different hypotheses about molecular transport mechanisms. We hypothesized that the H+-transport mediated by ANT and uncoupling proteins (UCP) has a similar regulation pattern and can be explained by the fatty acid cycling concept. The reconstitution of purified recombinant ANT1 in the planar lipid bilayers allowed us to measure the membrane current after the direct application of transmembrane potential ΔΨ, which would correspond to the mitochondrial states III and IV. Experimental results reveal that ANT1 does not contribute to a basal proton leak. Instead, it mediates H+ transport only in the presence of long-chain fatty acids (FA), as already known for UCPs. It depends on FA chain length and saturation, implying that FA’s transport is confined to the lipid-protein interface. Purine nucleotides with the preference for ATP and ADP inhibited H+ transport. Specific inhibitors of ATP/ADP transport, carboxyatractyloside or bongkrekic acid, also decreased proton transport. The H+ turnover number was calculated based on ANT1 concentration determined by fluorescence correlation spectroscopy and is equal to 14.6 ± 2.5 s−1. Molecular dynamic simulations revealed a large positively charged area at the protein/lipid interface that might facilitate FA anion’s transport across the membrane. ANT’s dual function—ADP/ATP and H+ transport in the presence of FA—may be important for the regulation of mitochondrial membrane potential and thus for potential-dependent processes in mitochondria. Moreover, the expansion of proton-transport modulating drug targets to ANT1 may improve the therapy of obesity, cancer, steatosis, cardiovascular and neurodegenerative diseases.

scholarly journals ADENINE NUCLEOTIDE-INDUCED CONTRACTION OF THE INNER MITOCHONDRIAL MEMBRANE

1973 ◽  
Vol 56 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Clinton D. Stoner ◽  
Howard D. Sirak
Keyword(s):  
Binding Sites ◽  
Mitochondrial Membrane ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Nucleotide Binding ◽  
Nucleotide Exchange ◽  
Inner Mitochondrial Membrane ◽  
Inner Membrane ◽  
Nucleotide Binding Sites ◽  
Bongkrekic Acid

In bovine heart mitochondria bongkrekic acid at concentrations as low as about 4 nmol/mg protein (a) completely inhibits phosphorylation of exogenous adenosine diphosphate (ADP) and dephosphorylation of exogenous adenosine triphosphate (ATP), (b) completely reverses atractyloside inhibition of inner membrane contraction induced by exogenous adenine nucleotides, and (c) decreases the amount of adenine nucleotide required to elicit maximal exogenous adenine nucleotide-induced inner membrane contraction to a level which appears to correspond closely with the concentration of contractile, exogenous adenine nucleotide binding sites Bongkrekic acid at concentrations greater than 4 nmol/mg protein induces inner membrane contraction which seems to depend on the presence of endogenous ADP and/or ATP. The findings appear to be consistent with the interpretations (a) that the inner mitochondrial membrane contains two types of contractile, adenine nucleotide binding sites, (b) that the two sites differ markedly with regard to adenine nucleotide affinity, (c) that the high affinity site is identical with the adenine nucleotide exchange carrier, (d) that the low affinity site is accessible exclusively to endogenous adenine nucleotides and is largely unoccupied in the absence of bongkrekic acid, and (e) that bongkrekic acid increases the affinity of both sites in proportion to the amount of the antibiotic bound to the inner membrane.

scholarly journals Kinetic characteristics of propofol-induced inhibition of electron-transfer chain and fatty acid oxidation in human and rodent skeletal and cardiac muscles

2019 ◽  
Author(s):  
Tomáš Urban ◽  
Petr Waldauf ◽  
Adéla Krajčová ◽  
Kateřina Jiroutková ◽  
Milada Halačová ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Mitochondrial Membrane ◽  
Acid Oxidation ◽  
Kinetic Characteristics ◽  
Inner Mitochondrial Membrane ◽  
Electron Transfer Chain ◽  
Respiratory Complexes ◽  
Transfer Chain

AbstractIntroductionPropofol causes a profound inhibition of fatty acid oxidation (FAO) and reduces spare electron transfer chain (ETC) capacity in a range of human and rodent cells and tissues – a feature that might be related to the pathogenesis of Propofol Infusion Syndrome. We aimed to explore the mechanism of propofol-induced alteration of bioenergetic pathways by describing its kinetic characteristics.MethodsWe obtained samples of skeletal and cardiac muscle from Wistar rat (n=3) and human subjects: vastus lateralis from hip surgery patients (n=11) and myocardium from brain-dead organ donors (n=10). We assessed mitochondrial functional indices using standard SUIT protocol and high resolution respirometry in fresh tissue homogenates with or without short-term exposure to a range of propofol concentration (2.5-100 μg/ml). After finding concentrations of propofol causing partial inhibition of a particular pathways, we used that concentration to construct kinetic curves by plotting oxygen flux against substrate concentration during its stepwise titration in the presence or absence of propofol. By spectrophotometry we also measured the influence of the same propofol concentrations on the activity of isolated respiratory complexes.ResultsWe found that human muscle and cardiac tissues are more sensitive to propofol-mediated inhibition of bioenergetic pathways than rats tissue. In human homogenates, palmitoyl carnitine-driven respiration was inhibited at much lower concentrations of propofol than that required for a reduction of ETC capacity, suggesting FAO inhibition mechanism different from downstream limitation or carnitine-palmitoyl transferase-1 inhibition. Inhibition of Complex I was characterised by more marked reduction of Vmax, in keeping with non-competitive nature of the inhibition and the pattern was similar to the inhibition of Complex II or ETC capacity. There was no inhibition of Complex IV nor increased leak through inner mitochondrial membrane with up to 100 μg/ml of propofol. If measured in isolation by spectrophotometry, propofol 10 μg/ml did not affect the activity of any respiratory complexes.ConclusionIn human skeletal and heart muscle homogenates, propofol in concentrations that are achieved in propofol-anaesthetized patients, causes a direct inhibition of fatty acid oxidation, in addition to inhibiting flux of electrons through inner mitochondrial membrane. The inhibition is more marked in human as compared to rodent tissues.

scholarly journals stress sensitive B Encodes an Adenine Nucleotide Translocase in Drosophila melanogaster

Genetics ◽  
1999 ◽  
Vol 153 (2) ◽  
pp. 891-903 ◽  
Author(s):  
Yong Q Zhang ◽  
John Roote ◽  
Saverio Brogna ◽  
Andrew W Davis ◽  
Daniel A Barbash ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Sibling Species ◽  
Interspecific Hybrids ◽  
Mitochondrial Membrane ◽  
Adenine Nucleotide ◽  
Adenine Nucleotide Translocase ◽  
Differential Splicing ◽  
Inner Mitochondrial Membrane

Abstract Adenine nucleotide translocases (ANT) are required for the exchange of ADP and ATP across the inner mitochondrial membrane. They are essential for life, and most eukaryotes have at least two different Ant genes. Only one gene had been described from Drosophila, and this had not been characterized genetically. We show that mutations in this gene correspond to the previously described loci, sesB and l(1)9Ed. Immediately adjacent to this gene is another encoding a second ANT protein, which has 78% identity to that encoded by sesB/l(1)9Ed. These two genes are transcribed from a common promoter, and their mRNAs are produced by differential splicing. Hutter and Karch suggested that the sesB ANT gene corresponded to Hmr, a gene identified by an allele that rescues otherwise inviable interspecific hybrids between Drosophila melanogaster and its sibling species. This hypothesis is not supported by our study of the ANT genes of D. melanogaster.

Absorption and metabolism of [3H]arachidonic and [14C]linoleic acid in essential fatty acid-deficient rats

1990 ◽  
Vol 259 (1) ◽  
pp. G116-G124 ◽  
Author(s):  
L. Hjelte ◽  
T. Melin ◽  
A. Nilsson ◽  
B. Strandvik
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Linoleic Acid ◽  
Essential Fatty Acid ◽  
Mitochondrial Membrane ◽  
Inner Mitochondrial Membrane ◽  
Fecal Fat ◽  
Essential Fatty Acid Deficient ◽  
Drastic Increase ◽  
Fat Excretion

[3H]arachidonic acid (20:4) and [14C]linoleic acid (18:2) were fed in a triolein emulsion to essential fatty acid-deficient (EFAD) rats and to age-matched controls. Tissues were analyzed for radioactivity of different lipid classes after 1, 2, and 4 h. As in earlier studies [Nilsson and Melin. Am. J. Physiol. 255 (Gastrointest. Liver Physiol. 19): G612-G618, 1988], control rats retained more [3H]20:4 than [14C]18:2 in all organs except adipose tissue. In EFAD rats, recovery of [14C]18:2 was increased in small intestine, liver, heart, and kidneys. In comparison to controls, EFAD rats retained much more [14C]18:2 in phospholipids of these organs. The increase in the incorporation of both 3H and 14C into phosphatidylethanolamine was particularly pronounced. Another striking feature was the drastic increase in the retention after 4 h of 14C in cardiolipin, which is specifically located in the inner mitochondrial membrane. In contrast, incorporation of both 3H and 14C into phosphatidylinositol was decreased or unchanged in EFAD rats. Although fecal fat excretion was increased there was no evidence for a malabsorption or an increased retention in intestinal triacyglycerol of the radioactive fatty acids in EFAD rats. The proportion of [14C]18:2 that had been converted to [14C]20:4 was generally low but increased significantly with time in the liver and intestine of EFAD rats.

scholarly journals Human HSPA9 (mtHsp70, mortalin) interacts with lipid bilayers containing cardiolipin, a major component of the inner mitochondrial membrane

2020 ◽  
Vol 1862 (11) ◽  
pp. 183436 ◽  
Author(s):  
Paulo Roberto Dores-Silva ◽  
David M. Cauvi ◽  
Vanessa T.R. Kiraly ◽  
Júlio C. Borges ◽  
Antonio De Maio
Keyword(s):  
Lipid Bilayers ◽  
Mitochondrial Membrane ◽  
Inner Mitochondrial Membrane

scholarly journals Adenine Nucleotide Translocase 1 Expression Is Coupled to the HSP27-Mediated TLR4 Signaling in Cardiomyocytes

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1588 ◽  
Author(s):  
Julia Winter ◽  
Elke Hammer ◽  
Jacqueline Heger ◽  
Heinz-Peter Schultheiss ◽  
Ursula Rauch ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Adenine Nucleotide ◽  
Heart Tissue ◽  
Neonatal Rat ◽  
Adenine Nucleotide Translocase ◽  
Inner Mitochondrial Membrane ◽  
Tlr4 Signaling ◽  
Rat Cardiomyocytes

The cardiac-specific overexpression of the adenine nucleotide translocase 1 (ANT1) has cardioprotective effects in various experimental heart disease models. Here, we analyzed the link between ANT1 expression and heat shock protein 27 (HSP27)-mediated toll-like receptor 4 (TLR4) signaling, which represents a novel communication pathway between mitochondria and the extracellular environment. The interaction between ANT1 and HSP27 was identified by co-immunoprecipitation from neonatal rat cardiomyocytes. ANT1 transgenic (ANT1-TG) cardiomyocytes demonstrated elevated HSP27 expression levels. Increased levels of HSP27 were released from the ANT1-TG cardiomyocytes under both normoxic and hypoxic conditions. Extracellular HSP27 stimulated TLR4 signaling via protein kinase B (AKT). The HSP27-mediated activation of the TLR4 pathway was more pronounced in ANT1-TG cardiomyocytes than in wild-type (WT) cardiomyocytes. HSP27-specific antibodies inhibited TLR4 activation and the expression of HSP27. Inhibition of the HSP27-mediated TLR4 signaling pathway with the TLR4 inhibitor oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (OxPAPC) reduced the mitochondrial membrane potential (∆ψm) and increased caspase 3/7 activity, which are both markers for cell stress. Conversely, treating cardiomyocytes with recombinant HSP27 protein stimulated TLR4 signaling, induced HSP27 and ANT1 expression, and stabilized the mitochondrial membrane potential. The activation of HSP27 signaling was verified in ischemic ANT1-TG heart tissue, where it correlated with ANT1 expression and the tightness of the inner mitochondrial membrane. Our study shows a new mechanism by which ANT1 is part of the cardioprotective HSP27-mediated TLR4 signaling.

scholarly journals The Role of Adenine Nucleotide Translocase in the Mitochondrial Permeability Transition

Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2686
Author(s):  
Nickolay Brustovetsky
Keyword(s):  
Atp Synthase ◽  
Mitochondrial Membrane ◽  
Mitochondrial Permeability Transition ◽  
Adenine Nucleotide ◽  
Permeability Transition ◽  
Adenine Nucleotide Translocase ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Permeability ◽  
F0f1 Atp Synthase

The mitochondrial permeability transition, a Ca2+-induced significant increase in permeability of the inner mitochondrial membrane, plays an important role in various pathologies. The mitochondrial permeability transition is caused by induction of the permeability transition pore (PTP). Despite significant effort, the molecular composition of the PTP is not completely clear and remains an area of hot debate. The Ca2+-modified adenine nucleotide translocase (ANT) and F0F1 ATP synthase are the major contenders for the role of pore in the PTP. This paper briefly overviews experimental results focusing on the role of ANT in the mitochondrial permeability transition and proposes that multiple molecular entities might be responsible for the conductance pathway of the PTP. Consequently, the term PTP cannot be applied to a single specific protein such as ANT or a protein complex such as F0F1 ATP synthase, but rather should comprise a variety of potential contributors to increased permeability of the inner mitochondrial membrane.

Calcium transport and inner mitochondrial membrane damage in renal cortical mitochondria

1985 ◽  
Vol 248 (6) ◽  
pp. F876-F889 ◽  
Author(s):  
J. M. Weinberg ◽  
H. D. Humes
Keyword(s):  
Fatty Acid ◽  
Membrane Permeability ◽  
Respiratory Function ◽  
Mitochondrial Membrane ◽  
Membrane Damage ◽  
Ruthenium Red ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Membrane Permeability ◽  
Isolated Mitochondria

Ca2+ uptake and efflux processes, as they are manifested during procedures used for isolation of renal cortical mitochondria, were characterized in order to provide a better basis for making inferences from isolated mitochondria about the in vivo state of mitochondrial Ca2+ homeostasis in both normal and injured tissues and to better define the mechanisms by which Ca2+ mediates injury to renal cortical mitochondria. Mitochondrial Ca2+ uptake predictably occurred when the capacity of the Ca2+ chelator added to the isolating medium to maintain free Ca2+ in the submicromolar range was exhausted unless ruthenium red was present to specifically inhibit the Ca2+ uniport. Ca2+ uptake during isolation ultimately led to loss of accumulated Ca2+ and intramitochondrial K+ as well as to deterioration of respiratory function. Extramitochondrial Ca2+ also evoked the latter two events in the absence of Ca2+ uptake but only at much higher medium Ca2+ levels than were required when Ca2+ uptake was allowed to occur. Studies using mitochondria loaded with known amounts of Ca2+ at 4 degrees C and then subjected to a reisolation procedure including all the steps of normal isolation demonstrated that phosphate markedly potentiated Ca2+-induced alterations of mitochondrial membrane permeability properties. Of several agents studied singly, fatty acid-free albumin was most effective in blocking Ca2+ + phosphate-induced alterations of mitochondrial membrane permeability. The protective effect of fatty acid-free albumin was further enhanced by combining it with Mg2+, dibucaine, or oligomycin + ADP. This study thus quantitatively defined conditions under which Ca2+ uptake can be expected to occur during mitochondrial isolation, demonstrated that the effects of this Ca2+ uptake on mitochondrial properties are similar to those previously elucidated in mitochondria studied at warmer temperatures, and defined methods suitable for blocking such Ca2+ movements and their deleterious effects.

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