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Fragiadaki I, Katogiritis A, Calogeropoulou T, Brückner H, Scoulica E. Synergistic combination of alkylphosphocholines with peptaibols in targeting Leishmania infantum in vitro. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2018; 8:194-202. [PMID: 29631127 PMCID: PMC6039304 DOI: 10.1016/j.ijpddr.2018.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 02/20/2018] [Accepted: 03/19/2018] [Indexed: 12/11/2022]
Abstract
Anti-leishmanial treatment increasingly encounters therapeutic limitations due to drug toxicity and development of resistance. The effort for new therapeutic strategies led us to work on combinations of chemically different compounds that could yield enhanced leishmanicidal effect. Peptaibols are a special type of antimicrobial peptides that are able to form ion channels in cell membranes and potentially affect cell viability. We assayed the antileishmanial activity of two well studied helical peptaibols, the 16-residue antiamoebin and the 20-residue alamethicin-analogue suzukacillin, and we evaluated the biological effect of their combination with the alkylphosphocholine miltefosine and its synthetic analogue TC52. The peptaibols tested exhibited only moderate antileishmanial activity, however their combination with miltefosine had a super-additive effect against the intracellular parasite (combination index 0.83 and 0.43 for antiamoebin and suzukacillin respectively). Drug combinations altered the redox stage of promastigotes, rapidly dissipated mitochondrial membrane potential and induced concatenation of mitochondrial network promoting spheroidal morphology. These results evidenced a potent and specific antileishmanial effect of the peptaibols/miltefosine combinations, achieved with significantly lower concentrations of the compounds compared to monotherapy. Furthermore, they revealed the importance of exploring novel classes of bioactive compounds such as peptaibols and demonstrated for the first time that they can act in synergy with currently used antileishmanial drugs to improve the therapeutic outcome.
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Affiliation(s)
- Irene Fragiadaki
- University of Crete, Department of Clinical Microbiology and Microbial Pathogenesis, Faculty of Medicine, P.O. Box 2208, Heraklion, Greece
| | - Anna Katogiritis
- University of Crete, Department of Clinical Microbiology and Microbial Pathogenesis, Faculty of Medicine, P.O. Box 2208, Heraklion, Greece
| | - Theodora Calogeropoulou
- National Hellenic Research Foundation, Institute of Biology Medicinal Chemistry and Biotechnology, 48 Vassileos Constantinou Ave., 116 35, Athens, Greece
| | - Hans Brückner
- Institute of Nutritional Sciences, Interdisciplinary Research Center (IFZ), University of Giessen, 35390, Giessen, Germany
| | - Effie Scoulica
- University of Crete, Department of Clinical Microbiology and Microbial Pathogenesis, Faculty of Medicine, P.O. Box 2208, Heraklion, Greece.
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Tanudjaja E, Hoshi N, Su YH, Hamamoto S, Uozumi N. Kup-mediated Cs + uptake and Kdp-driven K + uptake coordinate to promote cell growth during excess Cs + conditions in Escherichia coli. Sci Rep 2017; 7:2122. [PMID: 28522840 PMCID: PMC5437092 DOI: 10.1038/s41598-017-02164-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 04/07/2017] [Indexed: 01/05/2023] Open
Abstract
The physiological effects of caesium (Cs) on living cells are poorly understood. Here, we examined the physiological role of Cs+ on the activity of the potassium transporters in E. coli. In the absence of potassium (K+), Kup-mediated Cs+ uptake partially supported cell growth, however, at a much lower rate than with sufficient K+. In K+-limited medium (0.1 mM), the presence of Cs+ (up to 25 mM) in the medium enhanced growth as much as control medium containing 1 mM K+. This effect depended on the maintenance of basal levels of intracellular K+ by other K+ uptake transporters. Higher amounts of K+ (1 mM) in the medium eliminated the positive effect of Cs+ on growth, and revealed the inhibitory effect of high Cs+ on the growth of wild-type E. coli. Cells lacking Kdp, TrkG and TrkH but expressing Kup grew less well when Cs+ was increased in the medium. A kdp mutant contained an increased ratio of Cs+/K+ in the presence of high Cs+ in the medium and consequently was strongly inhibited in growth. Taken together, under excess Cs+ conditions Kup-mediated Cs+ influx sustains cell growth, which is supported by intracellular K+ supplied by Kdp.
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Affiliation(s)
- Ellen Tanudjaja
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai, 980-8579, Japan
| | - Naomi Hoshi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai, 980-8579, Japan
| | - Yi-Hsin Su
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai, 980-8579, Japan
| | - Shin Hamamoto
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai, 980-8579, Japan
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai, 980-8579, Japan.
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Two-Dimensional Crystallization Procedure, from Protein Expression to Sample Preparation. BIOMED RESEARCH INTERNATIONAL 2015; 2015:693869. [PMID: 26413539 PMCID: PMC4564634 DOI: 10.1155/2015/693869] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 07/02/2015] [Indexed: 11/18/2022]
Abstract
Membrane proteins play important roles for living cells. Structural studies of membrane proteins provide deeper understanding of their mechanisms and further aid in drug design. As compared to other methods, electron microscopy is uniquely suitable for analysis of a broad range of specimens, from small proteins to large complexes. Of various electron microscopic methods, electron crystallography is particularly well-suited to study membrane proteins which are reconstituted into two-dimensional crystals in lipid environments. In this review, we discuss the steps and parameters for obtaining large and well-ordered two-dimensional crystals. A general description of the principle in each step is provided since this information can also be applied to other biochemical and biophysical methods. The examples are taken from our own studies and published results with related proteins. Our purpose is to give readers a more general idea of electron crystallography and to share our experiences in obtaining suitable crystals for data collection.
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Kuang Q, Purhonen P, Pattipaka T, Ayele YH, Hebert H, Koeck PJB. A Refined Single-Particle Reconstruction Procedure to Process Two-Dimensional Crystal Images from Transmission Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2015; 21:876-885. [PMID: 25990985 DOI: 10.1017/s1431927615000616] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Single-particle reconstruction (SPR) and electron crystallography (EC), two major applications in electron microscopy, can be used to determine the structure of membrane proteins. The three-dimensional (3D) map is obtained from separated particles in conventional SPR, but from periodic unit cells in EC. Here, we report a refined SPR procedure for processing 2D crystal images. The method is applied to 2D crystals of melibiose permease, a secondary transporter in Escherichia coli. The current procedure is improved from our previously published one in several aspects. The "gold standard Fourier shell correlation" resolution of our final reconstruction reaches 13 Å, which is significantly better than the previously obtained 17 Å resolution. The choices of different refinement parameters for reconstruction are discussed. Our refined SPR procedure could be applied to determine the structure of other membrane proteins in small or locally distorted 2D crystals, which are not ideal for EC.
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Affiliation(s)
- Qie Kuang
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
| | - Pasi Purhonen
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
| | - Thirupathi Pattipaka
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
| | - Yohannes H Ayele
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
| | - Hans Hebert
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
| | - Philip J B Koeck
- Karolinska Institutet,Department of Biosciences and Nutrition and KTH Royal Institute of Technology,School of Technology and Health,Novum,S-14183 Huddinge,Sweden
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Kuang Q, Purhonen P, Hebert H. Structure of potassium channels. Cell Mol Life Sci 2015; 72:3677-93. [PMID: 26070303 PMCID: PMC4565861 DOI: 10.1007/s00018-015-1948-5] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 05/09/2015] [Accepted: 06/03/2015] [Indexed: 12/25/2022]
Abstract
Potassium channels ubiquitously exist in nearly all kingdoms of life and perform diverse but important functions. Since the first atomic structure of a prokaryotic potassium channel (KcsA, a channel from Streptomyces lividans) was determined, tremendous progress has been made in understanding the mechanism of potassium channels and channels conducting other ions. In this review, we discuss the structure of various kinds of potassium channels, including the potassium channel with the pore-forming domain only (KcsA), voltage-gated, inwardly rectifying, tandem pore domain, and ligand-gated ones. The general properties shared by all potassium channels are introduced first, followed by specific features in each class. Our purpose is to help readers to grasp the basic concepts, to be familiar with the property of the different domains, and to understand the structure and function of the potassium channels better.
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Affiliation(s)
- Qie Kuang
- Department of Biosciences and Nutrition, Karolinska Institutet, Novum, 14183, Huddinge, Sweden.
- School of Technology and Health, KTH Royal Institute of Technology, Novum, 14183, Huddinge, Sweden.
| | - Pasi Purhonen
- Department of Biosciences and Nutrition, Karolinska Institutet, Novum, 14183, Huddinge, Sweden
| | - Hans Hebert
- Department of Biosciences and Nutrition, Karolinska Institutet, Novum, 14183, Huddinge, Sweden
- School of Technology and Health, KTH Royal Institute of Technology, Novum, 14183, Huddinge, Sweden
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Kuang Q, Purhonen P, Jegerschöld C, Koeck PJB, Hebert H. Free RCK arrangement in Kch, a putative escherichia coli potassium channel, as suggested by electron crystallography. Structure 2014; 23:199-205. [PMID: 25497729 DOI: 10.1016/j.str.2014.10.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 10/08/2014] [Accepted: 10/21/2014] [Indexed: 01/24/2023]
Abstract
The ligand-gated potassium channels are stimulated by various kinds of messengers. Previous studies showed that ligand-gated potassium channels containing RCK domains (the regulator of the conductance of potassium ion) form a dimer of tetramer structure through the RCK octameric gating ring in the presence of detergent. Here, we have analyzed the structure of Kch, a channel of this type from Escherichia coli, in a lipid environment using electron crystallography. By combining information from the 3D map of the transmembrane part of the protein and docking of an atomic model of a potassium channel, we conclude that the RCK domains face the solution and that an RCK octameric gating ring arrangement does not form under our crystallization condition. Our findings may be applied to other potassium channels that have an RCK gating ring arrangement.
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Affiliation(s)
- Qie Kuang
- Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden; School of Technology and Health, KTH Royal Institute of Technology, 14183 Huddinge, Sweden.
| | - Pasi Purhonen
- Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden
| | - Caroline Jegerschöld
- Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden
| | - Philip J B Koeck
- Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden; School of Technology and Health, KTH Royal Institute of Technology, 14183 Huddinge, Sweden
| | - Hans Hebert
- Department of Biosciences and Nutrition, Karolinska Institutet, 14183 Huddinge, Sweden; School of Technology and Health, KTH Royal Institute of Technology, 14183 Huddinge, Sweden.
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