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Shapira T, Christofferson M, Av-Gay Y. The antimicrobial activity of innate host-directed therapies: A systematic review. Int J Antimicrob Agents 2024; 63:107138. [PMID: 38490573 DOI: 10.1016/j.ijantimicag.2024.107138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 02/23/2024] [Accepted: 03/07/2024] [Indexed: 03/17/2024]
Abstract
Intracellular human pathogens are the deadliest infectious diseases and are difficult to treat effectively due to their protection inside the host cell and the development of antimicrobial resistance (AMR). An emerging approach to combat these intracellular pathogens is host-directed therapies (HDT), which harness the innate immunity of host cells. HDT rely on small molecules to promote host protection mechanisms that ultimately lead to pathogen clearance. These therapies are hypothesized to: (1) possess indirect yet broad, cross-species antimicrobial activity, (2) effectively target drug-resistant pathogens, (3) carry a reduced susceptibility to the development of AMR and (4) have synergistic action with conventional antimicrobials. As the field of HDT expands, this systematic review was conducted to collect a compendium of HDT and their characteristics, such as the host mechanisms affected, the pathogen inhibited, the concentrations investigated and the magnitude of pathogen inhibition. The evidential support for the main four HDT hypotheses was assessed and concluded that HDT demonstrate robust cross-species activity, are active against AMR pathogens, clinical isolates and laboratory-adapted pathogens. However, limited information exists to support the notion that HDT are synergistic with canonical antimicrobials and are less predisposed to AMR development.
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Affiliation(s)
- Tirosh Shapira
- Department of Medicine, Division of Infectious Disease, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Matthew Christofferson
- Department of Microbiology and Immunology, Division of Infectious Disease, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Yossef Av-Gay
- Department of Medicine, Division of Infectious Disease, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada; Department of Microbiology and Immunology, Division of Infectious Disease, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada.
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2
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Dürvanger Z, Juhász T, Liliom K, Harmat V. Structures of calmodulin-melittin complexes show multiple binding modes lacking classical anchoring interactions. J Biol Chem 2023; 299:104596. [PMID: 36906144 PMCID: PMC10140167 DOI: 10.1016/j.jbc.2023.104596] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/11/2023] Open
Abstract
Calmodulin (CaM) is a Ca2+ sensor protein found in all eukaryotic cells that regulates a large number of target proteins in a Ca2+ concentration-dependent manner. As a transient type hub protein, it recognizes linear motifs of its targets, though for the Ca2+-dependent binding no consensus sequence was identified. Its complex with melittin, a major component of bee venom, is often used as a model system of protein - protein complexes. Yet, the structural aspects of the binding are not well understood, as only diverse, low-resolution data are available concerning the association. We present the crystal structure of melittin in complex with Ca2+-saturated calmodulins from two, evolutionarily distant species, Homo sapiens and Plasmodium falciparum representing three binding modes of the peptide. Results - augmented by molecular dynamics simulations - indicate that multiple binding modes can exist for CaM-melittin complexes, as an intrinsic characteristic of the binding. While the helical structure of melittin remains, swapping of its salt bridges and partial unfolding of its C-terminal segment can occur. In contrast to the classical way of target recognition by CaM, we found that different sets of residues can anchor at the hydrophobic pockets of CaM, which were considered as main recognition sites. Finally, the nanomolar binding affinity of the CaM-melittin complex is created by an ensemble of arrangements of similar stability - tight binding is achieved not by optimized specific interactions but by simultaneously satisfying less optimal interaction patterns in co-existing different conformers.
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Affiliation(s)
- Zsolt Dürvanger
- Laboratory of Structural Chemistry and Biology, Institute of Chemistry, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Tünde Juhász
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Budapest, Hungary
| | - Károly Liliom
- Department of Biophysics and Radiation Biology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Veronika Harmat
- Laboratory of Structural Chemistry and Biology, Institute of Chemistry, ELTE Eötvös Loránd University, Budapest, Hungary; ELKH-ELTE Protein Modelling Research Group, Eötvös Loránd Research Network, Budapest, Hungary.
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3
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Plasmodium falciparum histidine triad protein and calmodulin modulates calcium homeostasis and intracellular proteolysis. Biochem Biophys Res Commun 2018; 503:722-728. [DOI: 10.1016/j.bbrc.2018.06.067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 06/13/2018] [Indexed: 10/28/2022]
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4
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Meier A, Erler H, Beitz E. Targeting Channels and Transporters in Protozoan Parasite Infections. Front Chem 2018; 6:88. [PMID: 29637069 PMCID: PMC5881087 DOI: 10.3389/fchem.2018.00088] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 03/12/2018] [Indexed: 12/25/2022] Open
Abstract
Infectious diseases caused by pathogenic protozoa are among the most significant causes of death in humans. Therapeutic options are scarce and massively challenged by the emergence of resistant parasite strains. Many of the current anti-parasite drugs target soluble enzymes, generate unspecific oxidative stress, or act by an unresolved mechanism within the parasite. In recent years, collections of drug-like compounds derived from large-scale phenotypic screenings, such as the malaria or pathogen box, have been made available to researchers free of charge boosting the identification of novel promising targets. Remarkably, several of the compound hits have been found to inhibit membrane proteins at the periphery of the parasites, i.e., channels and transporters for ions and metabolites. In this review, we will focus on the progress made on targeting channels and transporters at different levels and the potential for use against infections with apicomplexan parasites mainly Plasmodium spp. (malaria) and Toxoplasma gondii (toxoplasmosis), with kinetoplastids Trypanosoma brucei (sleeping sickness), Trypanosoma cruzi (Chagas disease), and Leishmania ssp. (leishmaniasis), and the amoeba Entamoeba histolytica (amoebiasis).
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Affiliation(s)
- Anna Meier
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Holger Erler
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Eric Beitz
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel, Kiel, Germany
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5
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Budu A, Gomes MM, Melo PM, El Chamy Maluf S, Bagnaresi P, Azevedo MF, Carmona AK, Gazarini ML. Calmidazolium evokes high calcium fluctuations in Plasmodium falciparum. Cell Signal 2015; 28:125-135. [PMID: 26689736 DOI: 10.1016/j.cellsig.2015.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 11/30/2015] [Accepted: 12/07/2015] [Indexed: 10/22/2022]
Abstract
Calcium and calmodulin (CaM) are important players in eukaryote cell signaling. In the present study, by using a knockin approach, we demonstrated the expression and localization of CaM in all erythrocytic stages of Plasmodium falciparum. Under extracellular Ca(2+)-free conditions, calmidazolium (CZ), a potent CaM inhibitor, promoted a transient cytosolic calcium ([Ca(2+)]cyt) increase in isolated trophozoites, indicating that CZ mobilizes intracellular sources of calcium. In the same extracellular Ca(2+)-free conditions, the [Ca(2+)]cyt rise elicited by CZ treatment was ~3.5 fold higher when the endoplasmic reticulum (ER) calcium store was previously depleted ruling out the mobilization of calcium from the ER by CZ. The effects of the Ca(2+)/H(+) ionophore ionomycin (ION) and the Na(+)/H(+) ionophore monensin (MON) suggest that the [Ca(2+)]cyt-increasing effect of CZ is driven by the removal of Ca(2+) from at least one Ca(2+)-CaM-related (CaMR) protein as well as by the mobilization of Ca(2+) from intracellular acidic calcium stores. Moreover, we showed that the mitochondrion participates in the sequestration of the cytosolic Ca(2+) elicited by CZ. Finally, the modulation of membrane Ca(2+) channels by CZ and thapsigargin (THG) was demonstrated. The opened channels were blocked by the unspecific calcium channel blocker Co(2+) but not by 2-APB (capacitative calcium entry inhibitor) or nifedipine (L-type Ca(2+) channel inhibitor). Taken together, the results suggested that one CaMR protein is an important modulator of calcium signaling and homeostasis during the Plasmodium intraerythrocytic cell cycle, working as a relevant intracellular Ca(2+) reservoir in the parasite.
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Affiliation(s)
- Alexandre Budu
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Mayrim M Gomes
- Departamento de Biociências, Universidade Federal de São Paulo, Santos, SP, Brazil
| | - Pollyana M Melo
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Sarah El Chamy Maluf
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Piero Bagnaresi
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Mauro F Azevedo
- Instituto de Ciências Biomédicas, Universidade de São Paulo, SP, Brazil
| | - Adriana K Carmona
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
| | - Marcos L Gazarini
- Departamento de Biociências, Universidade Federal de São Paulo, Santos, SP, Brazil.
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6
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Plattner H, Sehring IM, Mohamed IK, Miranda K, De Souza W, Billington R, Genazzani A, Ladenburger EM. Calcium signaling in closely related protozoan groups (Alveolata): non-parasitic ciliates (Paramecium, Tetrahymena) vs. parasitic Apicomplexa (Plasmodium, Toxoplasma). Cell Calcium 2012; 51:351-82. [PMID: 22387010 DOI: 10.1016/j.ceca.2012.01.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/10/2012] [Accepted: 01/12/2012] [Indexed: 12/20/2022]
Abstract
The importance of Ca2+-signaling for many subcellular processes is well established in higher eukaryotes, whereas information about protozoa is restricted. Recent genome analyses have stimulated such work also with Alveolates, such as ciliates (Paramecium, Tetrahymena) and their pathogenic close relatives, the Apicomplexa (Plasmodium, Toxoplasma). Here we compare Ca2+ signaling in the two closely related groups. Acidic Ca2+ stores have been characterized in detail in Apicomplexa, but hardly in ciliates. Two-pore channels engaged in Ca2+-release from acidic stores in higher eukaryotes have not been stingently characterized in either group. Both groups are endowed with plasma membrane- and endoplasmic reticulum-type Ca2+-ATPases (PMCA, SERCA), respectively. Only recently was it possible to identify in Paramecium a number of homologs of ryanodine and inositol 1,3,4-trisphosphate receptors (RyR, IP3R) and to localize them to widely different organelles participating in vesicle trafficking. For Apicomplexa, physiological experiments suggest the presence of related channels although their identity remains elusive. In Paramecium, IP3Rs are constitutively active in the contractile vacuole complex; RyR-related channels in alveolar sacs are activated during exocytosis stimulation, whereas in the parasites the homologous structure (inner membrane complex) may no longer function as a Ca2+ store. Scrutinized comparison of the two closely related protozoan phyla may stimulate further work and elucidate adaptation to parasitic life. See also "Conclusions" section.
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Affiliation(s)
- H Plattner
- Department of Biology, University of Konstanz, P.O. Box 5560, 78457 Konstanz, Germany.
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Reimão JQ, Tempone AG. Investigation into in vitro anti-leishmanial combinations of calcium channel blockers and current anti-leishmanial drugs. Mem Inst Oswaldo Cruz 2011; 106:1032-8. [DOI: 10.1590/s0074-02762011000800022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 10/25/2011] [Indexed: 11/21/2022] Open
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8
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Plasmodium falciparum: Growth response to potassium channel blocking compounds. Exp Parasitol 2008; 120:280-5. [DOI: 10.1016/j.exppara.2008.07.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 07/22/2008] [Accepted: 07/23/2008] [Indexed: 11/23/2022]
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Garcia CRS, de Azevedo MF, Wunderlich G, Budu A, Young JA, Bannister L. Plasmodium in the postgenomic era: new insights into the molecular cell biology of malaria parasites. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 266:85-156. [PMID: 18544493 DOI: 10.1016/s1937-6448(07)66003-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In this review, we bring together some of the approaches toward understanding the cellular and molecular biology of Plasmodium species and their interaction with their host red blood cells. Considerable impetus has come from the development of new methods of molecular genetics and bioinformatics, and it is important to evaluate the wealth of these novel data in the context of basic cell biology. We describe how these approaches are gaining valuable insights into the parasite-host cell interaction, including (1) the multistep process of red blood cell invasion by the merozoite; (2) the mechanisms by which the intracellular parasite feeds on the red blood cell and exports parasite proteins to modify its cytoadherent properties; (3) the modulation of the cell cycle by sensing the environmental tryptophan-related molecules; (4) the mechanism used to survive in a low Ca(2+) concentration inside red blood cells; (5) the activation of signal transduction machinery and the regulation of intracellular calcium; (6) transfection technology; and (7) transcriptional regulation and genome-wide mRNA studies in Plasmodium falciparum.
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Affiliation(s)
- Celia R S Garcia
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, CEP 05508-900, São Paulo, SP, Brazil
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10
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Beraldo FH, Mikoshiba K, Garcia CRS. Human malarial parasite, Plasmodium falciparum, displays capacitative calcium entry: 2-aminoethyl diphenylborinate blocks the signal transduction pathway of melatonin action on the P. falciparum cell cycle. J Pineal Res 2007; 43:360-4. [PMID: 17910604 DOI: 10.1111/j.1600-079x.2007.00486.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The malarial parasite senses the environment to modulate its own cycle. Knowledge of the mechanisms for regulation signaling processes at the invasion, maturation, as well as division of Plasmodium falciparum before reinvasion would represent a major breakthrough and, therefore, might open new avenues for therapy. We have previously reported that melatonin modulates the circadian rhythm of malarial parasites through the activation of phospholipase C (PLC), production of InsP3, and induction of calcium release from intracellular stores. To further investigate the molecular mechanism of melatonin's action, we have used the InsP3 modulator 2-aminoethyl diphenylborinate (2-APB) given in a culture of P. falciparum parasites. Here we show that the melatonin acts on Plasmodium cell cycle through InsP3 signaling as 2-APB blocks melatonin's effect on calcium release. The function of the InsP3 signaling can be regarded as an important event for parasite invasion and maturation process, since addition of the PLC inhibitor, U73122 into Plasmodium-infected red blood cells impairs parasite invasion in vitro. By using 8BrcAMP, we also report here that Plasmodia displays a 'capacitative calcium entry' mechanism for amplification of calcium signals throughout the cytoplasm.
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Affiliation(s)
- Flávio H Beraldo
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
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Farias SL, Gazarini ML, Melo RL, Hirata IY, Juliano MA, Juliano L, Garcia CRS. Cysteine-protease activity elicited by Ca2+ stimulus in Plasmodium. Mol Biochem Parasitol 2005; 141:71-9. [PMID: 15811528 DOI: 10.1016/j.molbiopara.2005.01.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Revised: 01/11/2005] [Accepted: 01/26/2005] [Indexed: 11/26/2022]
Abstract
Bloodstage malaria parasites require proteolytic activity for key processes as invasion, hemoglobin degradation and merozoite escape from red blood cells (RBCs). We investigated by confocal microscopy the presence of cysteine-protease activity elicited by calcium stimulus in Plasmodium chabaudi and Plasmodium falciparum in free trophozoites or for the later parasite within RBC using fluorescence resonance energy transfer (FRET) peptides. Peptide probes access, to either free or intraerythrocytic parasites, was also tested by selecting a range of fluorescent peptides (653-3146 Da molecular mass) labeled with Abz or FITC. In the present work we show that Ca2+ stimulus elicited by treatment with either melatonin, thapsigargin, ionomicin or nigericin, promotes an increase of substrate hydrolysis, which was blocked by the specific cysteine-protease inhibitor E-64 and the intracellular Ca2+ chelator, BAPTA. When parasites were treated with cytoplasmic Ca2+ releasing compounds, a cysteine-protease was labeled in the parasite cytoplasm by the fluorescent specific irreversible inhibitor, Ethyl-Eps-Leu-Tyr-Cap-Lys(Abz)-NH2, where Ethyl-Eps is Ethyl-(2S,3S)-oxirane-2,3-dicarboxylate. In summary, we demonstrate that P. chabaudi and P. falciparum have a cytoplasmic dependent cysteine-protease activity elicited by Ca2+.
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Affiliation(s)
- Shirley L Farias
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil
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Sauvage V, Aubert D, Bonhomme A, Pinon JM, Millot JM. P-glycoprotein inhibitors modulate accumulation and efflux of xenobiotics in extra and intracellular Toxoplasma gondii. Mol Biochem Parasitol 2004; 134:89-95. [PMID: 14747146 DOI: 10.1016/j.molbiopara.2003.08.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We examined xenobiotic transport and the effects of P-glycoprotein (Pgp) inhibitors on efflux function in Toxoplasma gondii tachyzoites. The fluorescence emission of JC-1 and daunorubicin (Pgp substrates) was determined in both extracellular tachyzoites and T. gondii-infected human KB cells. Dye accumulation and efflux were modulated by verapamil (Vp) and cyclosporin A (CsA), both of which are Pgp inhibitors. Red JC-1 emission was measured from 10(6) extracellular tachyzoites, using spectrofluorometry. The increase in red emission was significant from 1 microM concentration of both drugs and was higher with CsA than with Vp. Compared with untreated tachyzoites, JC-1 efflux was inhibited by 3 microM CsA and 3 microM Vp. With intracellular tachyzoites, the fluorescence distribution of daunorubicin (DNR) between the parasitophorous vacuole and the host cell was modulated by Vp and CsA. In media free of CsA and Vp, DNR emission inside intracellular tachyzoites was very weak, as observed by confocal microscopy. In the presence of CsA or Vp, DNR emission was markedly enhanced in tachyzoites but not in the whole vacuole. The modulation of DNR uptake seems to involve the tachyzoite membrane rather than the parasitophorous vacuole or host cell membranes. It suggests that Vp would inhibit the DNR efflux from intracellular tachyzoites through a transitory effect. In conclusion, these two Pgp inhibitors increase both extracellular and intracellular dye accumulation in living T. gondii, pointing to the existence of a transmembrane transport mediated by a Pgp homologue located on the parasite membrane complex.
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Affiliation(s)
- Virginie Sauvage
- Laboratoire de Parasitologie-Mycologie, UFR de Médecine, UPRES EA 2070, IFR53 CHU, 51 rue Cognacq Jay, Reims 51096, France
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Abstract
Throughout the intraerythrocytic phase of its lifecycle the malaria parasite is separated from the extracellular medium by the plasma membrane of its host erythrocyte and by the parasitophorous vacuole in which the parasite is enclosed. The intracellular parasite itself has, at its surface, a plasma membrane, and has a variety of membrane-bound organelles which carry out a range of biochemical functions. Each of the various membranes of the infected cell have in them proteins that facilitate the movement of molecules and ions from one side of the membrane to the other. These 'channels' and 'transporters' play a central role in the physiology of the parasitised cell. From a clinical viewpoint they are of interest both as potential targets in their own right, and as potential drug targeting routes capable of mediating the entry of cytotoxic drugs into the appropriate compartment of the infected cell. In this review both of these aspects are considered.
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Affiliation(s)
- Kiaran Kirk
- School of Biochemistry and Molecular Biology, Australian National University, Faculty of Science, 0200 ACT, Canberra, Australia.
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Mitchell D, Bell A. PEST sequences in the malaria parasite Plasmodium falciparum: a genomic study. Malar J 2003; 2:16. [PMID: 12857354 PMCID: PMC198282 DOI: 10.1186/1475-2875-2-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2003] [Accepted: 06/23/2003] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Inhibitors of the protease calpain are known to have selectively toxic effects on Plasmodium falciparum. The enzyme has a natural inhibitor calpastatin and in eukaryotes is responsible for turnover of proteins containing short sequences enriched in certain amino acids (PEST sequences). The genome of P. falciparum was searched for this protease, its natural inhibitor and putative substrates. METHODS The publicly available P. falciparum genome was found to have too many errors to permit reliable analysis. An earlier annotation of chromosome 2 was instead examined. PEST scores were determined for all annotated proteins. The published genome was searched for calpain and calpastatin homologs. RESULTS Typical PEST sequences were found in 13% of the proteins on chromosome 2, including a surprising number of cell-surface proteins. The annotated calpain gene has a non-biological "intron" that appears to have been created to avoid an unrecognized frameshift. Only the catalytic domain has significant similarity with the vertebrate calpains. No calpastatin homologs were found in the published annotation. CONCLUSION A calpain gene is present in the genome and many putative substrates of this enzyme have been found. Calpastatin homologs may be found once the re-annotation is completed. Given the selective toxicity of calpain inhibitors, this enzyme may be worth exploring further as a potential drug target.
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Affiliation(s)
- David Mitchell
- Department of Microbiology, Moyne Institute, Trinity College, Dublin 2, Republic of Ireland
| | - Angus Bell
- Department of Microbiology, Moyne Institute, Trinity College, Dublin 2, Republic of Ireland
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Efron L, Dagan A, Gaidukov L, Ginsburg H, Mor A. Direct interaction of dermaseptin S4 aminoheptanoyl derivative with intraerythrocytic malaria parasite leading to increased specific antiparasitic activity in culture. J Biol Chem 2002; 277:24067-72. [PMID: 11937508 DOI: 10.1074/jbc.m202089200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Antiplasmodial activity of the dermaseptin S4 derivative K(4)S4(1-13) (P) was shown to be mediated by lysis of the host cells. To identify antiplasmodial peptides with enhanced selectivity, we produced and screened new derivatives based on P and singled out the aminoheptanoylated peptide (NC7-P) for its improved antiplasmodial properties. Compared with P, NC7-P displayed both increased antiparasitic efficiency and reduced hemolysis, including against infected cells. Antiplasmodial activity of P and its derivative was time-dependent and irreversible, implying a cytotoxic effect. But, whereas the dose dependence of growth inhibition and hemolysis of infected cells overlapped when treated with P, NC7-P exerted more than 50% growth inhibition at peptide concentrations that did not cause hemolysis. Noticeably, NC7-P but not P, dissipated the parasite plasma membrane potential and caused depletion of intraparasite potassium at nonhemolytic conditions. Confocal microscopy analysis of infected cells localized the rhodaminated derivative in association with parasite membranes and intraerythrocytic tubulovesicular structures, whereas in normal cells, the peptide localized exclusively at the plasma membrane. Overall, the data demonstrate that antimicrobial peptides can be engineered to act specifically on the membrane of intracellular parasites and support a mechanism whereby NC7-P crosses the host cell plasma membrane and disrupts the parasite membrane(s).
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Affiliation(s)
- Leah Efron
- Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram 91904 Jerusalem, Israel
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Dagan A, Efron L, Gaidukov L, Mor A, Ginsburg H. In vitro antiplasmodium effects of dermaseptin S4 derivatives. Antimicrob Agents Chemother 2002; 46:1059-66. [PMID: 11897590 PMCID: PMC127115 DOI: 10.1128/aac.46.4.1059-1066.2002] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 13-residue dermaseptin S4 derivative K(4)S4(1-13)a (P) was previously shown to kill intraerythrocytic malaria parasites through the lysis of the host cells. In this study, we have sought peptides that will kill the parasite without lysing the erythrocyte. To produce such peptides, 26 compounds of variable structure and size were attached to the N terminus of P and screened for antiplasmodium and hemolytic activities in cultures of Plasmodium falciparum. Results from this screen indicated that increased hydrophobicity results in amplified antiplasmodium effect, irrespective of the linearity or bulkiness of the additive. However, increased hydrophobicity also was generally associated with increased hemolysis, with the exception of two derivatives: propionyl-P (C3-P) and isobutyryl-P (iC4-P). Both acyl-peptides were more effective than P, with 50% growth inhibition at 3.8, 4.3, and 7.7 microM, respectively. The antiparasitic effect was time dependent and totally irreversible, implying a cytotoxic effect. The peptides were also investigated in parallel for their ability to inhibit parasite growth and to induce hemolysis in infected and uninfected erythrocytes. Whereas the dose dependence of growth inhibition and hemolysis of infected cells overlapped when cells were treated with P, the acyl-peptides exerted 50% growth inhibition at concentrations that did not cause hemolysis. Noticeably, the acyl derivatives, but not P, were able to dissipate the parasite plasma membrane potential and cause depletion of intraparasite potassium under nonhemolytic conditions. These results clearly demonstrate that the acyl-peptides can affect parasite viability in a manner that is dissociated from lysis of the host cell. Overall, the data indicate the potential usefulness of this strategy for development of selective peptides as investigative tools and eventually as antimalarial agents.
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Affiliation(s)
- Arie Dagan
- Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram 91904, Jerusalem, Israel
| | - Leah Efron
- Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram 91904, Jerusalem, Israel
| | - Leonid Gaidukov
- Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram 91904, Jerusalem, Israel
| | - Amram Mor
- Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram 91904, Jerusalem, Israel
- Corresponding author. Mailing address: Laboratory for Antimicrobial Peptides Investigation (L.A.P.I.), Wolfson Centre for Applied Structural Biology, The Hebrew University of Jerusalem, Givat Ram 91904, Jerusalem, Israel. Phone: (972 2) 65 85 295. Fax: (972 2) 65 85 573. E-mail:
| | - Hagai Ginsburg
- Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram 91904, Jerusalem, Israel
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Amaral L, Viveiros M, Kristiansen JE. Phenothiazines: potential alternatives for the management of antibiotic resistant infections of tuberculosis and malaria in developing countries. Trop Med Int Health 2001; 6:1016-22. [PMID: 11737839 DOI: 10.1046/j.1365-3156.2001.00804.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The in vitro and in vivo activity of phenothiazines against antibiotic susceptible and antibiotic resistant Mycobacterium tuberculosis and malaria-causing Plasmodia is reviewed. Given the facts that pulmonary tuberculosis and malaria are the major causes of death in developing countries, that both of these infections continue to escalate in their resistance to antibiotics, that the cost for the management of these infections is beyond that afforded by most developing nations, and lastly, that new and effective agents are not forthcoming from the pharmaceutical industry, the scientific rationale for the potential use of select phenothiazines for the management of these infections is presented.
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Affiliation(s)
- L Amaral
- Unit of Mycobacteriology, Institute of Hygiene and Tropical Medicine, Universidade Nova de Lisboa, Lisboa, Portugal.
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18
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Abstract
The malaria parasite is a unicellular eukaryotic organism which, during the course of its complex life cycle, invades the red blood cells of its vertebrate host. As it grows and multiplies within its host blood cell, the parasite modifies the membrane permeability and cytosolic composition of the host cell. The intracellular parasite is enclosed within a so-called parasitophorous vacuolar membrane, tubular extensions of which radiate out into the host cell compartment. Like all eukaryote cells, the parasite has at its surface a plasma membrane, as well as having a variety of internal membrane-bound organelles that perform a range of functions. This review focuses on the transport properties of the different membranes of the malaria-infected erythrocyte, as well as on the role played by the various membrane transport systems in the uptake of solutes from the extracellular medium, the disposal of metabolic wastes, and the origin and maintenance of electrochemical ion gradients. Such systems are of considerable interest from the point of view of antimalarial chemotherapy, both as drug targets in their own right and as routes for targeting cytotoxic agents into the intracellular parasite.
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Affiliation(s)
- K Kirk
- Division of Biochemistry and Molecular Biology, Faculty of Science, Australian National University, Canberra, Australian Capital Territory, Australia.
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19
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Krugliak M, Feder R, Zolotarev VY, Gaidukov L, Dagan A, Ginsburg H, Mor A. Antimalarial activities of dermaseptin S4 derivatives. Antimicrob Agents Chemother 2000; 44:2442-51. [PMID: 10952593 PMCID: PMC90083 DOI: 10.1128/aac.44.9.2442-2451.2000] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The hemolytic antimicrobial peptide dermaseptin S4 was recently shown to exert antimalarial activity. In this study, we attempted to understand the underlying mechanism(s) and identify derivatives with improved antimalarial activity. A number of dermaseptin S4 derivatives inhibited parasite growth with a 50% inhibitory concentration (IC(50)) in the micromolar range. Among these, the substituted S4 analog K(4)K(20)-S4 was the most potent (IC(50) = 0.2 microM), while its shorter version, K(4)-S4(1-13)a, retained a considerable potency (IC(50) = 6 microM). Both K(4)K(20)-S4 and K(4)-S4(1-13)a inhibited growth of the parasites more at the trophozoite stage than at the ring stage. Significant growth inhibition was observed after as little as 1 min of exposure to peptides and proceeded with nearly linear kinetics. The peptides selectively lysed infected red blood cells (RBC) while having a weaker effect on noninfected RBC. Thus, K(4)K(20)-S4 lysed trophozoites at concentrations similar to those that inhibited their proliferation, but trophozoites were >30-fold more susceptible than normal RBC to the lytic effect of K(4)K(20)-S4, the most hemolytic dermaseptin. The same trend was observed with K(4)-S4(1-13)a. The D isomers of K(4)K(20)-S4 or K(4)-S4(1-13)a were as active as the L counterparts, indicating that antimalarial activity of these peptides, like their membrane-lytic activity, is not mediated by specific interactions with a chiral center. Moreover, dissipation of transmembrane potential experiments with infected cells indicated that the peptides induce damage in the parasite's plasma membrane. Fluorescence confocal microscopy analysis of treated infected cells also indicated that the peptide is able to find its way through the complex series of membranes and interact directly with the intracellular parasite. Overall, the data showed that dermaseptins exert antimalarial activity by lysis of infected cells. Dermaseptin derivatives are also able to disrupt the parasite plasma membrane without harming that of the host RBC.
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Affiliation(s)
- M Krugliak
- The Institute of Life Sciences, The Hebrew University of Jerusalem, Israel
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20
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Garcia CR. Calcium homeostasis and signaling in the blood-stage malaria parasite. PARASITOLOGY TODAY (PERSONAL ED.) 1999; 15:488-91. [PMID: 10557149 DOI: 10.1016/s0169-4758(99)01571-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The nature of the mechanisms underlying Ca2+ homeostasis in malaria parasites has puzzled investigators for almost two decades. This review summarizes the current knowledge about Ca2+ homeostasis in Plasmodium spp and highlights some key aspects of this process that are specific to this parasite. Plasmodium spp are exposed, during their intracellular stage, not to the usual millimolar concentrations of Ca2+ found in body fluids, but rather to the very low Ca2+ environment of the host cell cytoplasm. Two crucial questions then arise: (1) how is Ca2+ homeostasis achieved by these protozoa; and (2) do they use Ca2+-based signaling pathways? By critically reviewing the recent literature in the field, Célia Garcia here provides at least some partial answers to these questions.
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Affiliation(s)
- C R Garcia
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, Travessa 14, no. 321, CEP 05508-900, São Paulo, SP, Brazil.
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21
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Wasserman M, Márquez AM, Urquiza M, Jiménez P. Increase of a calcium independent transglutaminase activity in the erythrocyte during the infection with Plasmodium falciparum. Mem Inst Oswaldo Cruz 1999; 94:95-100. [PMID: 10029918 DOI: 10.1590/s0074-02761999000100019] [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: 11/22/2022] Open
Abstract
We have studied the activity of a calcium dependent transglutaminase (EC 2.3.2.13) during the growth of the parasite Plasmodium falciparum inside the infected human erythrocyte. There is only one detectable transglutaminase in the two-cell-system, and its origin is erythrocytic. No activity was detected in preparations of the parasite devoid of erythrocyte cytoplasm. The Michaelis Menten constants (Km) of the enzyme for the substrates N'N' dimethylcaseine and putrescine were undistinguishable whether the cell extracts used in their determination were obtained from normal or from infected red cells. The total activity of transglutaminase in stringently synchronized cultures, measured at 0.5 mM Ca2+, decreased with the maturation of the parasite. However, a fraction which became irreversibly activated and independent of calcium concentration was detected. The proportion of this fraction grew with maturation; it represented only 20% of the activity in 20 hr-old-trophozoites while in 48-hr-schizonts it was more than 85% of the total activity. The activation of this fraction of transglutaminase did not depend on an increase in the erythrocyte cytoplasmic calcium, since most of the calcium was shown to be located in the parasite.
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Affiliation(s)
- M Wasserman
- Grupo de Bioquímica, Instituto Nacional de Salud, Bogotá, D.C., Colombia.
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22
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Saito-Ito A, He S, Kimura M, Matsumura T, Tanabe K. Cloning and structural analysis of the gene for cAMP-dependent protein kinase catalytic subunit from Plasmodium yoelii. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1269:1-5. [PMID: 7578264 DOI: 10.1016/0167-4889(95)00119-d] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We isolated the gene encoding the cAMP-dependent protein kinase catalytic subunit (cAPK[C]) from Plasmodium yoelii by screening a genomic library for the DNA fragment as produced by the polymerase chain reaction. The deduced protein of 341 amino acids conserves residues that are important for the function of serine/threonine protein kinases and shows the highest homology to cAPK[C]s of other organisms. However, P. yoelii cAPK[C] has 8 residues, which are perfectly conserved in cAPK[C]s of other organisms, radically replaced with residues having different side-chain properties. It is stressed that two radical replacements occur in regions for the binding with a regulatory subunit and/or a heat-stable inhibitor protein.
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Affiliation(s)
- A Saito-Ito
- Department of Medical Zoology, Kobe University School of Medicine, Japan
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23
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Mohan K, Dubey ML, Ganguly NK, Mahajan RC. Plasmodium falciparum and blood monocyte induced abnormalities in human erythrocyte cation homeostasis. Immunol Cell Biol 1994; 72:286-91. [PMID: 7806261 DOI: 10.1038/icb.1994.43] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The role of Plasmodium falciparum and activated blood monocytes in bringing about erythrocyte membrane lipid peroxidation and in altering the enzyme activity associated with Ca2+ and K+ efflux was studied. An attempt was made to investigate the role of parasite and monocyte-mediated reactive oxygen species (ROS) in inhibiting Ca(2+)-Mg2+ ATPase and Na(+)-K+ ATPase in order to find out the cause of reported high intra-erythrocytic calcium and depleted potassium levels in parasitized erythrocytes (PRBC). The PRBC showed enhanced lipid peroxidation as indicated by increased malonyldialdehyde (MDA) formation which coincided with the maturity of the parasite. This was further enhanced following exposure of PRBC to activated blood monocytes. The Ca(2+)-Mg2+ ATPase activity was decreased as the parasite matured and was further hampered significantly in mature parasite-infected red cells exposed to activated blood monocytes. There was a good negative correlation between MDA formation and Ca(2+)-efflux from red blood cells suggesting the negative influence of ROS on Ca(2+)-efflux. The Na(+)-K+ ATPase activity did not reveal any significant change, both during parasite maturation as well as upon exposure to ROS from activated monocytes. We therefore suggest that inhibition of Ca(2+)-efflux and the resulting increased cytosolic Ca2+ in PRBC might have a role in structural and functional abnormalities of red blood cell, thus enhancing the red cell loss during P. falciparum infection.
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Affiliation(s)
- K Mohan
- Department of Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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24
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Kitagawa I, Simanjuntak P, Hori K, Nagami N, Mahmud T, Shibuya H, Kobayashi M. Indonesian medicinal plants. VII. Seven new clerodane-type diterpenoids, peronemins A2, A3, B1, B2, B3, C1, and D1, from the leaves of Peronema canescens (Verbenaceae). Chem Pharm Bull (Tokyo) 1994; 42:1050-5. [PMID: 8069955 DOI: 10.1248/cpb.42.1050] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Seven new clerodane-type diterpenoids, named peronemins B2 (1), A2 (2), B1 (3), C1 (4), B3 (5), A3 (6), and D1 (7), were isolated from the leaves of Peronema canescens (Verbenaceae), an Indonesian medicinal plant collected in Bengkulu, Sumatera Island, Indonesia. The chemical structures of 1-7 have been elucidated on the basis of their chemical and physicochemical properties.
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Affiliation(s)
- I Kitagawa
- Faculty of Pharmaceutical Sciences, Osaka University, Japan
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25
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Robson KJ, Gamble Y, Acharya KR. Molecular modelling of malaria calmodulin suggests that it is not a suitable target for novel antimalarials. Philos Trans R Soc Lond B Biol Sci 1993; 340:39-53. [PMID: 8099744 DOI: 10.1098/rstb.1993.0047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The recent cloning and sequencing of many calmodulin genes permits alignment of DNA and protein sequences, as well as structural comparison based on homology modelling. The crystal structure of calmodulin places the four Ca(2+)-binding domains in a dumbbell-like configuration, with a large hydrophobic cleft in each half of the molecule. Calmodulin from Plasmodium falciparum has a high level of sequence identity (89%) with its mammalian counterpart. However, a lower degree of sequence conservation is observed among calmodulins from other lower eukaryotes. Potentially important differences in calmodulin sequences involve amino acids with side-chains forming the hydrophobic clefts as well as in the central helix; these differences could alter interactions with small hydrophobic molecules such as chloroquine and with enzymes modulated by calmodulin. Our modelling studies suggest that neither of the antimalarials examined (chloroquine and quinine) bind tightly to calmodulin. We conclude that the differences between host and parasite calmodulins are insufficient to merit this protein being chosen as a realistic target for antimalarial drug design. By contrast, our sequence comparisons reveal that the fungal calmodulins are significantly divergent from those of higher eukaryotes suggesting that at least in these species, calmodulin might be a target for novel antimycotic drugs.
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Affiliation(s)
- K J Robson
- MRC Molecular Haematology Unit, University of Oxford, John Radcliffe Hospital, Headington, U.K
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26
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Kimura M, Yamaguchi Y, Takada S, Tanabe K. Cloning of a Ca(2+)-ATPase gene of Plasmodium falciparum and comparison with vertebrate Ca(2+)-ATPases. J Cell Sci 1993; 104 ( Pt 4):1129-36. [PMID: 8314897 DOI: 10.1242/jcs.104.4.1129] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A Ca(2+)-ATPase gene was cloned from the genomic libraries of Plasmodium falciparum. From the deduced amino acid sequence of the gene, a 139 kDa protein with a total of 1228 amino acids was predicted. Sequence of a partial cDNA clone of the gene identified two introns near the 3′-end at the regions identical to the regions assumed for the Ca(2+)-ATPase gene of P. yoelii, a rodent malaria species. As compared with a variety of Ca(2+)-ATPases, the P. falciparum Ca(2+)-ATPase had the highest amino acid sequence homology (78%) to the P. yoelii Ca(2+)-ATPase, moderate homology (45-50%) to vertebrate sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases (SERCAs), and lowest homology (20%) to a plasma membrane Ca(2+)-ATPase. The P. falciparum protein conserved sequences and residues that are important for the function and/or structure of the organellar type Ca(2+)-ATPase, such as high affinity Ca(2+)-binding sites, fluorescein isothiocyanate (FITC)-binding regions, and the phosphorylation site, but the protein did not contain calmodulin-binding regions that occur in the plasma membrane type Ca(2+)-ATPase. Thus we concluded the cloned gene was the organellar type Ca(2+)-ATPase of P. falciparum. In a region between the phosphorylation site and FITC-binding region, the P. falciparum protein was about 200 residues longer than the rabbit SERCA and lacked a sequence that binds to phospholamban, a protein that regulates the activity of the rabbit SERCA.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Kimura
- Biophysics Laboratory, Osaka City University Medical School, Japan
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27
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Tipton DA, Dabbous MK. Binding and subcellular distribution of cyclosporine in human fibroblasts. J Cell Biochem 1993; 51:345-52. [PMID: 8501136 DOI: 10.1002/jcb.240510314] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The uptake, binding, and subcellular sites of accumulation of [3H]-cyclosporine (CS) in two human gingival fibroblast strains, GN 23 and GN 54, have been examined. GN 23 responds to CS treatment with a decrease in collagenolysis, while GN 54 does not. Binding of the drug was determined using [3H]-CS concentrations ranging from 10(-5) to 10(-8) M in the absence or presence of excess unlabeled CS (1 mM). The binding of the drug to both strains was specific and reached a plateau within 10 min, remaining at that level for up to 1 h. Scatchard analysis of the specific binding of [3H]-CS to the responsive GN 23 strain revealed two dissociation constants: KD = 5 x 10(-8) M (1.2 x 10(7) sites/cell) and KD = 1.4 x 10(-6) M (2.2 x 10(8) sites/cell). GN 54, on the other hand, had only one class of low affinity binding site (KD = 0.47 x 10(-6) M [1.2 x 10(8) sites/cell]). Unlabeled CS (0.01-1 mM) inhibited the binding of [3H]-CS in a dose-dependent manner to both strains, as did the calmodulin antagonist W-7, to a lesser extent. However, W-7 inhibited CS binding much more efficiently in GN 54 than in GN 23, suggesting that calmodulin may be the predominant CS receptor in GN 54. In both strains, 70% of the drug accumulated in the crude nuclear fraction after a 1 min incubation, with very little (< or = 4%) being membrane associated, and the remainder was in the cytosol.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D A Tipton
- Dental Research Center, University of Tennessee, Memphis 38163
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28
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McCallum-Deighton N, Holder AA. The role of calcium in the invasion of human erythrocytes by Plasmodium falciparum. Mol Biochem Parasitol 1992; 50:317-23. [PMID: 1741019 DOI: 10.1016/0166-6851(92)90229-d] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The role of calcium in the invasion of human erythrocytes by Plasmodium falciparum merozoites has been investigated using a variety of techniques. It has been demonstrated using calcium-depleted medium that invasion is dependent upon the presence of calcium and that neither magnesium, manganese or zinc may substitute for it, suggesting that the effect is calcium specific and not dependent upon a non-specific, charge-based mechanism. Using resealed erythrocyte ghosts and altering the internal and external concentrations of calcium and the chelator EGTA, it has been shown that the role of calcium in invasion, at least as far as the target cell is concerned, is in the extracellular environment. Similarly, loading either the schizont-infected, or target erythrocyte with the membrane permeant calcium chelator Indo-1, at concentrations sufficient to chelate approximately 100 times the concentration of resting cell calcium, produced no change in the parasite invasion rate. Consequently we conclude that calcium plays an extra-cellular role in merozoite invasion of the human erythrocyte.
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Affiliation(s)
- N McCallum-Deighton
- Division of Parasitology, National Institute for Medical Research, London, U.K
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29
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Scheibel LW. Role of calcium/calmodulin-mediated processes in protozoa. INTERNATIONAL REVIEW OF CYTOLOGY 1992; 134:165-242. [PMID: 1582773 DOI: 10.1016/s0074-7696(08)62029-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- L W Scheibel
- Department of Preventive Medicine, Uniformed Services University of the Health Sciences School of Medicine, Bethesda, Maryland 20814
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30
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Olaya P, Wasserman M. Effect of calpain inhibitors on the invasion of human erythrocytes by the parasite Plasmodium falciparum. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1096:217-21. [PMID: 2018795 DOI: 10.1016/0925-4439(91)90008-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
17 different proteinase inhibitors were screened for their effect on the erythrocyte invasion by the malaria parasite Plasmodium falciparum. The effect was tested when the inhibitors were present in the culture medium and when they were trapped into erythrocyte ghosts. A very strong inhibition of invasion was observed in the presence of calpain inhibitors, with IC50 in the order of 10(-7) M. Chymostatin, leupeptin, pepstatin A and bestatin also caused inhibition of the invasion, but with IC50 in the order of 10(-5) M. The results suggest that participation of various proteinases in the process and point to the possibility of a calpain-mediated proteolytic event. This study may explain previous observations on the role of calcium in the invasion of the human erythrocyte by Plasmodium falciparum.
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Affiliation(s)
- P Olaya
- Department of Biochemistry, Instituto Nacional de Salud, Bogotá, Colombia
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31
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Kawamoto F, Alejo-Blanco R, Fleck SL, Kawamoto Y, Sinden RE. Possible roles of Ca2+ and cGMP as mediators of the exflagellation of Plasmodium berghei and Plasmodium falciparum. Mol Biochem Parasitol 1990; 42:101-8. [PMID: 2172816 DOI: 10.1016/0166-6851(90)90117-5] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The roles of Ca2+ and cyclic nucleotides as secondary, intracellular messengers for exflagellation of Plasmodium berghei and Plasmodium falciparum were investigated. Treatment with Ca2+ antagonists such as TMB-8 (an inhibitor of intracellular Ca2+ release) or W-7 (a calmodulin inhibitor) strongly inhibited exflagellation induced by alkaline medium at pH 8.0 whereas EGTA (a Ca2+ chelator) or nicardipine and nifedipine (Ca2+ channel inhibitors) had no effect. These results may indicate that mobilization of parasites' internal resources of Ca2+ is a prerequisite for exflagellation. Agents which increase cAMP levels did not induce exflagellation at the non-permissive pH of 7.3, and had no significant inhibitory effect at the permissive pH of 8.0. IBMX (cAMP/cGMP-phosphodiesterase inhibitor), however, enhanced exflagellation at pH 7.3, indicating the possibility that cGMP, but not cAMP, may be involved in the induction of exflagellation. Furthermore, cGMP or agents which increase cGMP levels such as nitroprusside (a potent activator of guanylate cyclase), enhanced exflagellation at pH 7.3, whereas N-methyl-hydroxylamine (guanylate cyclase inhibitor) inhibited the exflagellation at pH 8.0. From these results, it may be concluded that the induction of exflagellation requires both Ca2+ mobilization and an increase in cGMP levels.
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Affiliation(s)
- F Kawamoto
- Department of Pure and Applied Biology, Imperial College, London, U.K
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32
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Tanabe K, Kato M, Izumo A, Hagiwara A, Doi S. Plasmodium chabaudi: in vivo effects of Ca2+ antagonists on chloroquine-resistant and chloroquine-sensitive parasites. Exp Parasitol 1990; 70:419-26. [PMID: 2323395 DOI: 10.1016/0014-4894(90)90126-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The effects of Ca2+ antagonists, verapamil, nicardipine, and diltiazem, on susceptibility to chloroquine were examined in mice infected with chloroquine-sensitive and chloroquine-resistant lines of Plasmodium chabaudi. In mice that received no chloroquine, daily injections of 50 mg/kg of verapamil, nicardipine, or diltiazem did not affect the growth of both sensitive and resistant parasites. When mice were injected daily with verapamil plus 2 to 3 mg/kg chloroquine, the chloroquine-sensitive parasite became more susceptible to chloroquine than the parasite in mice given chloroquine alone. On the other hand, in mice infected with chloroquine-resistant parasites, verapamil severely suppressed the growth of the parasite when accompanied by daily injections of 2 to 3 mg/kg of chloroquine, at which doses resistant parasites grew steadily in the absence of verapamil, indicating reversal of chloroquine resistance. This reversal was dose-dependent between 5 and 50 mg/kg of verapamil. Daily injections of nicardipine or diltiazem at 50 mg/kg also reversed resistance to chloroquine in resistant parasites. These results indicate that Ca2+ antagonists increase the susceptibility to chloroquine in a sensitive line of P. chabaudi and reverse chloroquine resistance in a resistant line.
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Affiliation(s)
- K Tanabe
- Laboratory of Biology, Osaka Institute of Technology, Japan
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