Dataset Information

Cardiolipin dynamics and binding to conserved residues in the mitochondrial ADP/ATP carrier.

ABSTRACT: Cardiolipin in eukaryotes is found in the mitochondrial inner membrane, where it interacts with membrane proteins and, although not essential, is necessary for the optimal activity of a number of proteins. One of them is the mitochondrial ADP/ATP carrier, which imports ADP into the mitochondrion and exports ATP. In the crystal structures, cardiolipin is bound to three equivalent sites of the ADP/ATP carrier, but its role is unresolved. Conservation of residues at these cardiolipin binding sites across other members of the mitochondrial carrier superfamily indicates cardiolipin binding is likely to be important for the function of all mitochondrial carriers. Multiscale simulations were performed in a cardiolipin-containing membrane to investigate the dynamics of cardiolipin around the yeast and bovine ADP/ATP carriers in a lipid bilayer and the properties of the cardiolipin-binding sites. In coarse-grain simulations, cardiolipin molecules bound to the carriers for longer periods of time than phosphatidylcholine and phosphatidylethanolamine lipids-with timescales in the tens of microseconds. Three long-lived cardiolipin binding sites overlapped with those in the crystal structures of the carriers. Other shorter-lived cardiolipin interaction sites were identified in both membrane leaflets. However, the timescales of the interactions were of the same order as phosphatidylcholine and phosphatidylethanolamine, suggesting that these sites are not specific for cardiolipin binding. The calculation of lipid binding times and the overlap of the cardiolipin binding sites between the structures and simulations demonstrate the potential of multiscale simulations to investigate the dynamics and behavior of lipids interacting with membrane proteins.

SUBMITTER: Duncan AL

PROVIDER: S-EPMC5988563 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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Cardiolipin dynamics and binding to conserved residues in the mitochondrial ADP/ATP carrier.

Duncan Anna L AL Ruprecht Jonathan J JJ Kunji Edmund R S ERS Robinson Alan J AJ

Biochimica et biophysica acta. Biomembranes 20180131 5

Cardiolipin in eukaryotes is found in the mitochondrial inner membrane, where it interacts with membrane proteins and, although not essential, is necessary for the optimal activity of a number of proteins. One of them is the mitochondrial ADP/ATP carrier, which imports ADP into the mitochondrion and exports ATP. In the crystal structures, cardiolipin is bound to three equivalent sites of the ADP/ATP carrier, but its role is unresolved. Conservation of residues at these cardiolipin binding sites ...[more]

PMID: 29366674

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Project description:An increasing number of commonly prescribed drugs are known to interfere with mitochondrial function, causing cellular toxicity, but the underlying mechanisms are largely unknown. Although often not considered, mitochondrial transport proteins form a significant class of potential mitochondrial off-targets. So far, most drug interactions have been reported for the mitochondrial ADP/ATP carrier (AAC), which exchanges cytosolic ADP for mitochondrial ATP. Here, we show inhibition of cellular respiratory capacity by only a subset of the 18 published AAC inhibitors, which questions whether all compound do indeed inhibit such a central metabolic process. This could be explained by the lack of a simple, direct model system to evaluate and compare drug-induced AAC inhibition. Methods: For its development, we have expressed and purified human AAC1 (hAAC1) and applied two approaches. In the first, thermostability shift assays were carried out to investigate the binding of these compounds to human AAC1. In the second, the effect of these compounds on transport was assessed in proteoliposomes with reconstituted human AAC1, enabling characterization of their inhibition kinetics. Results: Of the proposed inhibitors, chebulinic acid, CD-437 and suramin are the most potent with IC50-values in the low micromolar range, whereas another six are effective at a concentration of 100 μM. Remarkably, half of all previously published AAC inhibitors do not show significant inhibition in our assays, indicating that they are false positives. Finally, we show that inhibitor strength correlates with a negatively charged surface area of the inhibitor, matching the positively charged surface of the substrate binding site. Conclusion: Consequently, we have provided a straightforward model system to investigate AAC inhibition and have gained new insights into the chemical compound features important for inhibition. Better evaluation methods of drug-induced inhibition of mitochondrial transport proteins will contribute to the development of drugs with an enhanced safety profile.

Dataset Information

Cardiolipin dynamics and binding to conserved residues in the mitochondrial ADP/ATP carrier.

Publications

Cardiolipin dynamics and binding to conserved residues in the mitochondrial ADP/ATP carrier.

Similar Datasets

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