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Reddyrajula R, Perveen S, Negi A, Etikyala U, Manga V, Sharma R, Dalimba UK. N-Acyl phenothiazines as mycobacterial ATP synthase inhibitors: Rational design, synthesis and in vitro evaluation against drug sensitive, RR and MDR-TB. Bioorg Chem 2024; 151:107702. [PMID: 39142196 DOI: 10.1016/j.bioorg.2024.107702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 07/31/2024] [Accepted: 08/05/2024] [Indexed: 08/16/2024]
Abstract
The mycobacterial F-ATP synthase is responsible for the optimal growth, metabolism and viability of Mycobacteria, establishing it as a validated target for the development of anti-TB therapeutics. Herein, we report the discovery of an N-acyl phenothiazine derivative, termed PT6, targeting the mycobacterial F-ATP synthase. PT6 is bactericidal and active against the drug sensitive, Rifampicin-resistant as well as Multidrug-resistant tuberculosis strains. Compound PT6 showed noteworthy inhibition of F-ATP synthesis, exhibiting an IC50 of 0.788 µM in M. smegmatis IMVs and was observed that it could deplete intracellular ATP levels, exhibiting an IC50 of 30 µM. PT6 displayed a high selectivity towards mycobacterial ATP synthase compared to mitochondrial ATP synthase. Compound PT6 showed a minor synergistic effect in combination with Rifampicin and Isoniazid. PT6 demonstrated null cytotoxicity as confirmed by assessing its toxicity against VERO cell lines. Further, the binding mechanism and the activity profile of PT6 were validated by employing in silico techniques such as molecular docking, Prime MM/GBSA, DFT and ADMET analysis. These results suggest that PT6 presents an attractive lead for the discovery of a novel class of mycobacterial F-ATP synthase inhibitors.
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Affiliation(s)
- Rajkumar Reddyrajula
- Central Research Facility, National Institute of Technology Karnataka, Surathkal, Mangalore 575 025, India; Department of Chemical Sciences, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad 500 037, India
| | - Summaya Perveen
- Infectious Diseases Division, CSIR- Indian Institute of Integrative Medicine, Jammu 180 001, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Anjali Negi
- Infectious Diseases Division, CSIR- Indian Institute of Integrative Medicine, Jammu 180 001, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Umadevi Etikyala
- Medicinal Chemistry Laboratory, Department of Chemistry, Osmania University, Hyderabad 500 076, India
| | - Vijjulatha Manga
- Medicinal Chemistry Laboratory, Department of Chemistry, Osmania University, Hyderabad 500 076, India
| | - Rashmi Sharma
- Infectious Diseases Division, CSIR- Indian Institute of Integrative Medicine, Jammu 180 001, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India.
| | - Udaya Kumar Dalimba
- Organic and Materials Chemistry Laboratory, Department of Chemistry, National Institute of Technology Karnataka, Surathkal, Mangalore 575 025, India.
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Grimsey EM, Piddock LJV. Do phenothiazines possess antimicrobial and efflux inhibitory properties? FEMS Microbiol Rev 2020; 43:577-590. [PMID: 31216574 DOI: 10.1093/femsre/fuz017] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 06/12/2019] [Indexed: 12/30/2022] Open
Abstract
Antibiotic resistance is a global health concern; the rise of drug-resistant bacterial infections is compromising the medical advances that resulted from the introduction of antibiotics at the beginning of the 20th century. Considering that the presence of mutations within individuals in a bacterial population may allow a subsection to survive and propagate in response to selective pressure, as long as antibiotics are used in the treatment of bacterial infections, development of resistance is an inevitable evolutionary outcome. This, combined with the lack of novel antibiotics being released to the clinical market, means the need to develop alternative strategies to treat these resistant infections is critical. We discuss how the use of antibiotic adjuvants can minimise the appearance and impact of resistance. To this effect, several phenothiazine-derived drugs have been shown to potentiate the activities of antibiotics used to treat infections caused by Gram-positive and Gram-negative bacteria. Outside of their role as antipsychotic medications, we review the evidence to suggest that phenothiazines possess inherent antibacterial and efflux inhibitory properties enabling them to potentially combat drug resistance. We also discuss that understanding their mode of action is essential to facilitate the design of new phenothiazine derivatives or novel agents for use as antibiotic adjuvants.
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Affiliation(s)
- Elizabeth M Grimsey
- Institute of Microbiology & Infection, College of Medical & Dental Sciences, University of Birmingham, Edgbaston, United Kingdom
| | - Laura J V Piddock
- Institute of Microbiology & Infection, College of Medical & Dental Sciences, University of Birmingham, Edgbaston, United Kingdom
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3
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Buckner MMC, Ciusa ML, Meek RW, Moorey AR, McCallum GE, Prentice EL, Reid JP, Alderwick LJ, Di Maio A, Piddock LJV. HIV Drugs Inhibit Transfer of Plasmids Carrying Extended-Spectrum β-Lactamase and Carbapenemase Genes. mBio 2020; 11:e03355-19. [PMID: 32098822 PMCID: PMC7042701 DOI: 10.1128/mbio.03355-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 01/10/2020] [Indexed: 12/12/2022] Open
Abstract
Antimicrobial-resistant (AMR) infections pose a serious risk to human and animal health. A major factor contributing to this global crisis is the sharing of resistance genes between different bacteria via plasmids. The WHO lists Enterobacteriaceae, such as Escherichia coli and Klebsiella pneumoniae, producing extended-spectrum β-lactamases (ESBL) and carbapenemases as "critical" priorities for new drug development. These resistance genes are most often shared via plasmid transfer. However, finding methods to prevent resistance gene sharing has been hampered by the lack of screening systems for medium-/high-throughput approaches. Here, we have used an ESBL-producing plasmid, pCT, and a carbapenemase-producing plasmid, pKpQIL, in two different Gram-negative bacteria, E. coli and K. pneumoniae Using these critical resistance-pathogen combinations, we developed an assay using fluorescent proteins, flow cytometry, and confocal microscopy to assess plasmid transmission inhibition within bacterial populations in a medium-throughput manner. Three compounds with some reports of antiplasmid properties were tested; chlorpromazine reduced transmission of both plasmids and linoleic acid reduced transmission of pCT. We screened the Prestwick library of over 1,200 FDA-approved drugs/compounds. From this, we found two nucleoside analogue drugs used to treat HIV, abacavir and azidothymidine (AZT), which reduced plasmid transmission (AZT, e.g., at 0.25 μg/ml reduced pCT transmission in E. coli by 83.3% and pKpQIL transmission in K. pneumoniae by 80.8% compared to untreated controls). Plasmid transmission was reduced by concentrations of the drugs which are below peak serum concentrations and are achievable in the gastrointestinal tract. These drugs could be used to decolonize humans, animals, or the environment from AMR plasmids.IMPORTANCE More and more bacterial infections are becoming resistant to antibiotics. This has made treatment of many infections very difficult. One of the reasons this is such a large problem is that bacteria are able to share their genetic material with other bacteria, and these shared genes often include resistance to a variety of antibiotics, including some of our drugs of last resort. We are addressing this problem by using a fluorescence-based system to search for drugs that will stop bacteria from sharing resistance genes. We uncovered a new role for two drugs used to treat HIV and show that they are able to prevent the sharing of two different types of resistance genes in two unique bacterial strains. This work lays the foundation for future work to reduce the prevalence of resistant infections.
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Affiliation(s)
- Michelle M C Buckner
- Institute of Microbiology & Infection, College of Medical & Dental Sciences, University of Birmingham, Edgbaston, United Kingdom
| | - M Laura Ciusa
- Institute of Microbiology & Infection, College of Medical & Dental Sciences, University of Birmingham, Edgbaston, United Kingdom
| | - Richard W Meek
- Institute of Microbiology & Infection, College of Medical & Dental Sciences, University of Birmingham, Edgbaston, United Kingdom
| | - Alice R Moorey
- Institute of Microbiology & Infection, College of Medical & Dental Sciences, University of Birmingham, Edgbaston, United Kingdom
| | - Gregory E McCallum
- Institute of Microbiology & Infection, College of Medical & Dental Sciences, University of Birmingham, Edgbaston, United Kingdom
| | - Emma L Prentice
- Institute of Microbiology & Infection, College of Medical & Dental Sciences, University of Birmingham, Edgbaston, United Kingdom
| | - Jeremy P Reid
- Institute of Microbiology & Infection, College of Medical & Dental Sciences, University of Birmingham, Edgbaston, United Kingdom
| | - Luke J Alderwick
- Institute of Microbiology & Infection, School of Biosciences, University of Birmingham, Edgbaston, United Kingdom
| | - Alessandro Di Maio
- Birmingham Advanced Light Microscopy, School of Biosciences, University of Birmingham, Edgbaston, United Kingdom
| | - Laura J V Piddock
- Institute of Microbiology & Infection, College of Medical & Dental Sciences, University of Birmingham, Edgbaston, United Kingdom
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4
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Dubinin MV, Astashev ME, Penkov NV, Gudkov SV, Dyachenko IA, Samartsev VN, Belosludtsev KN. Effects of Phospholipase A2 Inhibitors on Bilayer Lipid Membranes. J Membr Biol 2016; 249:339-47. [DOI: 10.1007/s00232-016-9872-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 01/06/2016] [Indexed: 10/22/2022]
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Borges MBD, Dos Santos CG, Yokomizo CH, Sood R, Vitovic P, Kinnunen PKJ, Rodrigues T, Nantes IL. Characterization of hydrophobic interaction and antioxidant properties of the phenothiazine nucleus in mitochondrial and model membranes. Free Radic Res 2010; 44:1054-63. [DOI: 10.3109/10715762.2010.498826] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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6
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Morota S, Månsson R, Hansson MJ, Kasuya K, Shimazu M, Hasegawa E, Yanagi S, Omi A, Uchino H, Elmér E. Evaluation of putative inhibitors of mitochondrial permeability transition for brain disorders--specificity vs. toxicity. Exp Neurol 2009; 218:353-62. [PMID: 19348797 DOI: 10.1016/j.expneurol.2009.03.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 03/23/2009] [Accepted: 03/26/2009] [Indexed: 12/16/2022]
Abstract
Inhibition of mitochondrial permeability transition (mPT) has emerged as a promising approach for neuroprotection and development of well-tolerated mPT inhibitors with favorable blood-brain barrier penetration is highly warranted. In a recent study, 28 clinically available drugs with a common heterocyclic structure were identified as mPT inhibitors e.g. trifluoperazine, promethazine and nortriptyline. In addition, neuroprotection by structurally unrelated drugs e.g. neurosteroids, 4-hydroxy-tamoxifen and trimetazidine has been attributed to direct inhibition of mPT. The regulation of mPT is complex and highly dependent on the prevailing experimental conditions. Several features of mPT, such as swelling, depolarization or NADH oxidation, can also occur independently of the mPT phenomenon. Here, in isolated rodent brain-derived and human liver mitochondria, we re-evaluate drugs promoted as potent mPT inhibitors. We address the definition of an mPT inhibitor and present strategies to reliably detect mPT inhibition in vitro. Surprisingly, none of the 12 compounds tested displayed convincing mPT inhibition or effects comparable to cyclophilin D inhibition by the non-immunosuppressive cyclophilin inhibitor D-MeAla(3)-EtVal(4)-Cyclosporin (Debio 025). Propofol and 2-aminoethoxydiphenyl borate (2-APB) inhibited swelling in de-energized mitochondria but did not increase calcium retention capacity (CRC). Progesterone, trifluoperazine, allopregnanolone and 4-hydroxy-tamoxifen dose-dependently reduced CRC and respiratory control and were thus toxic rather than beneficial to mitochondrial function. Interestingly, topiramate increased CRC at high concentrations likely by a mechanism separate from direct mPT inhibition. We conclude that a clinically relevant mPT inhibitor should have a mitochondrial target and increase mitochondrial calcium retention at concentrations which can be translated to human use.
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Affiliation(s)
- Saori Morota
- Department of Clinical Sciences, Lund University, Sweden
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7
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Hong S, Pedersen PL. ATP synthase and the actions of inhibitors utilized to study its roles in human health, disease, and other scientific areas. Microbiol Mol Biol Rev 2008; 72:590-641, Table of Contents. [PMID: 19052322 PMCID: PMC2593570 DOI: 10.1128/mmbr.00016-08] [Citation(s) in RCA: 236] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
ATP synthase, a double-motor enzyme, plays various roles in the cell, participating not only in ATP synthesis but in ATP hydrolysis-dependent processes and in the regulation of a proton gradient across some membrane-dependent systems. Recent studies of ATP synthase as a potential molecular target for the treatment of some human diseases have displayed promising results, and this enzyme is now emerging as an attractive molecular target for the development of new therapies for a variety of diseases. Significantly, ATP synthase, because of its complex structure, is inhibited by a number of different inhibitors and provides diverse possibilities in the development of new ATP synthase-directed agents. In this review, we classify over 250 natural and synthetic inhibitors of ATP synthase reported to date and present their inhibitory sites and their known or proposed modes of action. The rich source of ATP synthase inhibitors and their known or purported sites of action presented in this review should provide valuable insights into their applications as potential scaffolds for new therapeutics for human and animal diseases as well as for the discovery of new pesticides and herbicides to help protect the world's food supply. Finally, as ATP synthase is now known to consist of two unique nanomotors involved in making ATP from ADP and P(i), the information provided in this review may greatly assist those investigators entering the emerging field of nanotechnology.
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Affiliation(s)
- Sangjin Hong
- Department of Biological Chemistry, Johns Hopkins University, School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205-2185, USA
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8
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Rodrigues T, Santos AC, Pigoso AA, Mingatto FE, Uyemura SA, Curti C. Thioridazine interacts with the membrane of mitochondria acquiring antioxidant activity toward apoptosis--potentially implicated mechanisms. Br J Pharmacol 2002; 136:136-42. [PMID: 11976278 PMCID: PMC1762107 DOI: 10.1038/sj.bjp.0704672] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We evaluated the effects of the phenothiazine derivative thioridazine on mechanisms of mitochondria potentially implicated in apoptosis, such as those involving reactive oxygen species (ROS) and cytochrome c release, as well as the involvement of drug interaction with mitochondrial membrane in these effects. Within the 0 - 100 microM range thioridazine did not reduce the free radical 1,1-diphenyl-2-picryl-hydrazyl (DPPH) nor did it chelate iron. However, at 10 microM thioridazine showed important antioxidant activity on mitochondria, characterized by inhibition of accumulation of mitochondria-generated O2*-, assayed as lucigenin-derived chemiluminescence, inhibition of Fe2+/citrate-mediated lipid peroxidation of the mitochondrial membrane (LPO), assayed as malondialdehyde generation, and inhibition of Ca2+/t-butyl hydroperoxide (t-BOOH)-induced mitochondrial permeability transition (MPT)/protein-thiol oxidation, assayed as mitochondrial swelling. Thioridazine respectively increased and decreased the fluorescence responses of mitochondria labelled with 1-aniline-8-naphthalene sulfonate (ANS) and 1-(4-trimethylammonium phenyl)-6 phenyl 1,3,5-hexatriene (TMA-DPH). The inhibition of LPO and MPT onset correlated well with the inhibition of cytochrome c release from mitochondria. We conclude that thioridazine interacts with the inner membrane of mitochondria, more likely close to its surface, acquiring antioxidant activity toward processes with potential implications in apoptosis such as O2*- accumulation, as well as LPO, MPT and associated release of cytochrome c.
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Affiliation(s)
- Tiago Rodrigues
- Department of Physics & Chemistry, Faculty of Pharmaceutical Sciences, University of São Paulo, 14040-903 Ribeirão Preto, São Paulo, Brazil
| | - Antonio C Santos
- Department of Clinical, Toxicological & Bromatological Analysis, Faculty of Pharmaceutical Sciences, University of São Paulo, 14040-903 Ribeirão Preto, São Paulo, Brazil
| | - Acácio A Pigoso
- Department of Physics & Chemistry, Faculty of Pharmaceutical Sciences, University of São Paulo, 14040-903 Ribeirão Preto, São Paulo, Brazil
| | - Fábio E Mingatto
- Department of Physics & Chemistry, Faculty of Pharmaceutical Sciences, University of São Paulo, 14040-903 Ribeirão Preto, São Paulo, Brazil
| | - Sérgio A Uyemura
- Department of Clinical, Toxicological & Bromatological Analysis, Faculty of Pharmaceutical Sciences, University of São Paulo, 14040-903 Ribeirão Preto, São Paulo, Brazil
| | - Carlos Curti
- Department of Physics & Chemistry, Faculty of Pharmaceutical Sciences, University of São Paulo, 14040-903 Ribeirão Preto, São Paulo, Brazil
- Author for correspondence:
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Hendrich AB, Wesolowska O, Michalak K. Trifluoperazine induces domain formation in zwitterionic phosphatidylcholine but not in charged phosphatidylglycerol bilayers. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1510:414-25. [PMID: 11342176 DOI: 10.1016/s0005-2736(00)00373-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The interaction of trifluoperazine with the zwitterionic lipids dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine and with anionic dimyristoylphosphatidylglycerol was studied by means of microcalorimetry and fluorescence spectroscopy. Intercalation of drug molecules into the lipid bilayers was confirmed by the observed differential scanning calorimetry peak broadening and the decrease in chain-melting temperatures. For trifluoperazine:lipid mole ratios higher than 0.4 and 0.6 (for dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine, respectively) the deconvolution of transition profiles into two Gaussian components was possible, which suggests phase separation in the studied mixtures. Deconvolution of the thermograms was not possible for any of the drug:dimyristoylphosphatidylglycerol mole ratios studied. To confirm the existence of phase separation in trifluoperazine-phosphatidylcholine mixtures fluorescence spectroscopy experiments were performed using Laurdan as a probe. From the generalised polarisation versus excitation wavelength dependences, recorded at different temperatures, we conclude that a phase separation occurs in the gel state of the studied trifluoperazine-phosphatidylcholine mixtures. We attribute the existence of domains in the bilayer to the dissimilar interactions of two protonation forms of trifluoperazine with phosphatidylcholine molecules. Structural defects present at domain boundaries could be related to the trifluoperazine induced increase of membrane permeability and fluidity. This may partially explain the mechanism of multidrug resistance modulation by trifluoperazine.
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Affiliation(s)
- A B Hendrich
- Department of Biophysics, Wroclaw Medical University, Ul. Chalubinskiego 10, 50-368, Wroclaw, Poland
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Curti C, Mingatto FE, Polizello AC, Galastri LO, Uyemura SA, Santos AC. Fluoxetine interacts with the lipid bilayer of the inner membrane in isolated rat brain mitochondria, inhibiting electron transport and F1F0-ATPase activity. Mol Cell Biochem 1999; 199:103-9. [PMID: 10544958 DOI: 10.1023/a:1006912010550] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effects of fluoxetine on the oxidative phosphorylation of mitochondria isolated from rat brain and on the kinetic properties of submitochondrial particle F1F0-ATPase were evaluated. The state 3 respiration rate supported by pyruvate + malate, succinate, or ascorbate + tetramethyl-p-phenylenediamine (TMPD) was substantially decreased by fluoxetine. The IC50 for pyruvate + malate oxidation was approximately 0.15 mM and the pattern of inhibition was the typical one of the electron-transport inhibitors, in that the drug inhibited both ADP- and carbonyl cyanide m-chlorophenylhydrazone (CCCP)-stimulated respirations and the former inhibition was not released by the uncoupler. Fluoxetine also decreased the activity of submitochondrial particle F1F0-ATPase (IC50 approximately 0.08 mM) even though K0.5 and activity of Triton X-100 solubilized enzyme were not changed substantially. As a consequence of these effects, fluoxetine decreased the rate of ATP synthesis and depressed the phosphorylation potential of mitochondria. Incubation of mitochondria or submitochondrial particles with fluoxetine under the conditions of respiration or F1F0-ATPase assays, respectively, caused a dose-dependent enhancement of 1-anilino-8-naphthalene sulfonate (ANS) fluorescence. These results show that fluoxetine indirectly and nonspecifically affects electron transport and F1F0)-ATPase activity inhibiting oxidative phosphorylation in isolated rat brain mitochondria. They suggest, in addition, that these effects are mediated by the drug interference with the physical state of lipid bilayer of inner mitochondrial membrane.
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Affiliation(s)
- C Curti
- Department of Physics and Chemistry, School of Pharmaceutical Sciences, University of São Paulo, Brasil
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García JJ, Tuena de Gómez-Puyou M, Gómez-Puyou A. Inhibition by trifluoperazine of ATP synthesis and hydrolysis by particulate and soluble mitochondrial F1: competition with H2PO4-. J Bioenerg Biomembr 1995; 27:127-36. [PMID: 7629044 DOI: 10.1007/bf02110340] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The effect of trifluoperazine (TFP) on the ATPase activity of soluble and particulate F1-ATPase and on ATP synthesis driven by succinate oxidation in submitochondrial particles from bovine heart was studied at pH 7.4 and 8.8. At the two pH, TFP inhibited ATP hydrolysis. Inorganic phosphate protected against the inhibiting action of TFP. The results on the effect of various concentrations of phosphate in the reversal of the action of TFP on hydrolysis at pH 7.4 and 8.8 showed that H2PO4- is the species that competes with TFP. The effect of TFP on oxidative phosphorylation was studied at concentrations that do not produce uncoupling or affect the aerobic oxidation of succinate (< 15 microM). TFP inhibited oxidative phosphorylation to a higher extent at pH 8.8 than at pH 7.4; this was through a diminution in the Vmax, and an increase in the Km for phosphate. Data on phosphate uptake during oxidative phosphorylation at several pH showed that H2PO4- is the true substrate for oxidative phosphorylation. Thus, in both synthesis and hydrolysis of ATP, TFP and H2PO4- interact with a common site. However, there is a difference in the sensitivity to TFP of ATP synthesis and hydrolysis; this is more noticeable at pH 8.8, i.e., ATPase activity of soluble F1 remains at about 40% of the activity of the control in a concentration range of TFP of 40-100 microM, whereas in oxidative phosphorylation 14 microM TFP produces a 60% inhibition of phosphate uptake.
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Affiliation(s)
- J J García
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, D.F. México
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12
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Chiang GG, Wooten DC, Dilley RA. Calcium-dependent interaction of chlorpromazine with the chloroplast 8-kilodalton CF0 protein and calcium gating of H+ fluxes between thylakoid membrane domains and the lumen. Biochemistry 1992; 31:5808-19. [PMID: 1377026 DOI: 10.1021/bi00140a017] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Earlier work suggested that Ca2+ ions in the chloroplast thylakoid lumen interact with thylakoid membrane proteins to produce a proton flux gating structure which functions to regulate the expression of the energy-coupling H+ gradient between localized and delocalized modes [Chiang, G., & Dilley, R. A. (1987) Biochemistry 26, 4911-4916]. In this work, one of the phenothiazine Ca2+ antagonists, chlorpromazine, was used as a photoaffinity probe to test for Ca(2+)-dependent binding of the probe to thylakoid proteins. [3H]Chlorpromazine photoaffinity-labels thylakoid polypeptides of Mr 8K and 6K, with generally much less label occurring in other proteins (some experiments showed labeled proteins at Mr 13K-15K). More label was incorporated in circumstances where it is expected that Ca2+ occupies the putative H+ flux gating site, compared to when the gating site is not occupied by calcium. The photoaffinity labeling of the 8-kDa protein was also influenced by the energization level of the thylakoids (less labeling under H+ uptake energization). The 8-kDa protein was identified by partial amino acid sequence data as subunit III of the thylakoid CF0 H+ channel complex. The partial amino acid sequence of the 6-kDa protein (19 residues were determined with some uncertainties) was compared to data in the GCG sequence analysis data base, and no clear identity to a known sequence was revealed. Neither the exact site of putative Ca2+ binding to the CF0 proteolipid nor the site of covalent attachment of the chlorpromazine to the CF0 component has been identified. Evidence for gating of energy-linked H+ fluxes by the hypothesized Ca(2+)-CF0 gating site came from the correlation between Ca(2+)-dependent binding of chlorpromazine to the CF0 8-kDa protein with inhibition of light-driven H+ uptake into the lumen but no inhibition of H+ uptake into sequestered membrane domains. When conditions favored a delocalized delta mu H+ coupling mode, less chlorpromazine was bound to the CF0 structure, and much larger amounts of H+ ions were accumulated in the lumen. The data support the hypothesis that Ca2+ ions act in concert with the 8-kDa CF0 protein (and perhaps another protein, the 6-kDa polypeptide?) in a gating mechanism for regulating the expression of the energy-coupling H+ gradient between localized or delocalized coupling modes.
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Affiliation(s)
- G G Chiang
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
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13
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Dabbeni-Sala F, Lippe G, Sorgato MC. Structural and functional modifications induced by diamide on the F0 sector of the mammalian ATP synthase. FEBS Lett 1991; 281:47-50. [PMID: 1826662 DOI: 10.1016/0014-5793(91)80355-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In this report data are presented which firmly establish that by treating isolated F0 with the thiol reagent diamide, two 25 kDa F0 subunits react to form a dimer of 45 kDa apparent molecular mass. This dimerising effect is correlated to the impairment of the binding of F1 to F0, both at microM and mM diamide concentrations. Under the latter condition, modification of other F0 subunits also occurs. Passive proton conductance through F0, as well as its sensitivity to N,N'-dicyclohexylcarbodiimide, are affected at low diamide concentration. Thus perturbation of the cysteine residue of the 25 kDa F0 subunit is sufficient for altering the ATP synthase proton channel.
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14
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Dabbeni-Sala F, Schiavo G, Palatini P. Mechanism of local anesthetic effect on mitochondrial ATP synthase as deduced from photolabelling and inhibition studies with phenothiazine derivatives. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1026:117-25. [PMID: 2143082 DOI: 10.1016/0005-2736(90)90341-k] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The mode of interaction between mitochondrial ATP synthase and two phenothiazine derivatives, chlorpromazine (CPZ) and trifluoperazine (TFP), was studied as a model for the interaction of local anesthetic drugs with membrane proteins. Photolabelling experiments demonstrated that CPZ and TFP interact with various subunits of either the peripheral F1 moiety of the membrane-embedded F0 sector. Both drugs, however, labelled the membrane sector much more heavily. Qualitative differences in labelling were observed between CPZ and TFP, indicating non-identical sites of interaction. These diversities appeared related to the different hydrophobicities of the two drugs since: (a) TFP, which has a higher lipid/water partition coefficient, labelled the more hydrophobic subunits more markedly than CPZ; (b) reduced glutathione, a hydrophilic free radical scavenger that does not penetrate the membrane continuum, had a negligible effect on the labelling by TFP, whereas it reduced the labelling of various subunits by CPZ; (c) the labelling by [3H]TFP was poorly antagonized by cold CPZ, whereas it was almost totally prevented by fluphenazine, a phenothiazine similar to TFP in hydrophobic character. Consistently, double-inhibition experiments showed that TFP and fluphenazine are mutually exclusive inhibitors of mitochondrial ATP synthase, whereas TFP and CPZ are mutually nonexclusive. The nature of the phospholipid bilayer influenced neither the labelling nor the inhibition patterns. The complex of these data indicate that tertiary amine local anesthetics affect the activity of membrane proteins by interacting with a multiplicity of relatively aspecific hydrophobic sites located preferentially, but not exclusively, on the membrane-embedded domains. It is suggested that at least two phenothiazine derivatives of different hydrophobicities be used in photolabelling experiments, before any generalization is made, since the molecular targets of these drugs vary according to their hydrophobic character.
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Affiliation(s)
- F Dabbeni-Sala
- Dipartimento di Farmacologia, Istituto di Patologia Generale, Padova, Italy
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