1
|
Abstract
Polyamines are polycationic organic amines that are required for all eukaryotic life, exemplified by the polyamine spermidine, which plays an essential role in translation. They also play more specialized roles that differ across species, and their chemical versatility has been fully exploited during the evolution of protozoan pathogens. These eukaryotic pathogens, which cause some of the most globally widespread infectious diseases, have acquired species-specific polyamine-derived metabolites with essential cellular functions and have evolved unique mechanisms that regulate their core polyamine biosynthetic pathways. Many of these parasitic species have lost enzymes and or transporters from the polyamine metabolic pathway that are found in the human host. These pathway differences have prompted drug discovery efforts to target the parasite polyamine pathways, and indeed, the only clinically approved drug targeting the polyamine biosynthetic pathway is used to manage human African trypanosomiasis. This Minireview will primarily focus on polyamine metabolism and function in Trypanosoma, Leishmania, and Plasmodium species, which are the causative agents of human African trypanosomiasis (HAT) and Chagas disease, Leishmaniasis, and malaria, respectively. Aspects of polyamine metabolism across a diverse group of protozoan pathogens will also be explored.
Collapse
Affiliation(s)
- Margaret A Phillips
- From the Departments of Biochemistry and Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9038
| |
Collapse
|
2
|
Vázquez C, Mejia-Tlachi M, González-Chávez Z, Silva A, Rodríguez-Zavala JS, Moreno-Sánchez R, Saavedra E. Buthionine sulfoximine is a multitarget inhibitor of trypanothione synthesis in Trypanosoma cruzi. FEBS Lett 2017; 591:3881-3894. [PMID: 29127710 DOI: 10.1002/1873-3468.12904] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 10/31/2017] [Accepted: 11/02/2017] [Indexed: 11/10/2022]
Abstract
Buthionine sulfoximine (BSO) induces decreased glutathione (GSH) and trypanothione [T(SH)2 ] pools in trypanosomatids, presumably because only gamma-glutamylcysteine synthetase (γECS) is blocked. However, some BSO effects cannot be explained by exclusive γECS inhibition; therefore, its effect on the T(SH)2 metabolism pathway in Trypanosoma cruzi was re-examined. Parasites exposed to BSO did not synthesize T(SH)2 even when supplemented with cysteine or GSH, suggesting trypanothione synthetase (TryS) inhibition by BSO. Indeed, recombinant γECS and TryS, but not GSH synthetase, were inhibited by BSO and kinetics and docking analyses on a TcTryS 3D model suggested BSO binding at the GSH site. Furthermore, parasites overexpressing γECS and TryS showed ~ 50% decreased activities after BSO treatment. These results indicated that BSO is also an inhibitor of TryS.
Collapse
Affiliation(s)
- Citlali Vázquez
- Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico city, México
| | - Marlen Mejia-Tlachi
- Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico city, México
| | - Zabdi González-Chávez
- Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico city, México
| | - Aketzalli Silva
- Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico city, México
| | | | - Rafael Moreno-Sánchez
- Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico city, México
| | - Emma Saavedra
- Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Mexico city, México
| |
Collapse
|
3
|
Volkov OA, Cosner CC, Brockway AJ, Kramer M, Booker M, Zhong S, Ketcherside A, Wei S, Longgood J, McCoy M, Richardson TE, Wring SA, Peel M, Klinger JD, Posner BA, De Brabander JK, Phillips MA. Identification of Trypanosoma brucei AdoMetDC Inhibitors Using a High-Throughput Mass Spectrometry-Based Assay. ACS Infect Dis 2017; 3:512-526. [PMID: 28350440 DOI: 10.1021/acsinfecdis.7b00022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Human African trypanosomiasis (HAT) is a fatal infectious disease caused by the eukaryotic pathogen Trypanosoma brucei (Tb). Available treatments are difficult to administer and have significant safety issues. S-Adenosylmethionine decarboxylase (AdoMetDC) is an essential enzyme in the parasite polyamine biosynthetic pathway. Previous attempts to develop TbAdoMetDC inhibitors into anti-HAT therapies failed due to poor brain exposure. Here, we describe a large screening campaign of two small-molecule libraries (∼400,000 compounds) employing a new high-throughput (∼7 s per sample) mass spectrometry-based assay for AdoMetDC activity. As a result of primary screening, followed by hit confirmation and validation, we identified 13 new classes of reversible TbAdoMetDC inhibitors with low-micromolar potency (IC50) against both TbAdoMetDC and T. brucei parasite cells. The majority of these compounds were >10-fold selective against the human enzyme. Importantly, compounds from four classes demonstrated high propensity to cross the blood-brain barrier in a cell monolayer assay. Biochemical analysis demonstrated that compounds from eight classes inhibited intracellular TbAdoMetDC in the parasite, although evidence for a secondary off-target component was also present. The discovery of several new TbAdoMetDC inhibitor chemotypes provides new hits for lead optimization programs aimed to deliver a novel treatment for HAT.
Collapse
Affiliation(s)
| | | | | | - Martin Kramer
- Genzyme Corp. (now Sanofi Genzyme), 153 Second Avenue, Waltham, Massachusetts 02451-1122, United States
| | - Michael Booker
- Genzyme Corp. (now Sanofi Genzyme), 153 Second Avenue, Waltham, Massachusetts 02451-1122, United States
| | | | | | | | | | | | - Thomas E. Richardson
- Scynexis, Inc. (now Avista Pharma Solutions), 3501 Tricenter Boulevard, Suite
C, Durham, North Carolina 27713, United States
| | - Stephen A. Wring
- Scynexis, Inc. (now Avista Pharma Solutions), 3501 Tricenter Boulevard, Suite
C, Durham, North Carolina 27713, United States
| | - Michael Peel
- Scynexis, Inc. (now Avista Pharma Solutions), 3501 Tricenter Boulevard, Suite
C, Durham, North Carolina 27713, United States
| | - Jeffrey D. Klinger
- Genzyme Corp. (now Sanofi Genzyme), 153 Second Avenue, Waltham, Massachusetts 02451-1122, United States
| | | | | | | |
Collapse
|
4
|
Wachsmuth LM, Johnson MG, Gavenonis J. Essential multimeric enzymes in kinetoplastid parasites: A host of potentially druggable protein-protein interactions. PLoS Negl Trop Dis 2017; 11:e0005720. [PMID: 28662026 PMCID: PMC5507555 DOI: 10.1371/journal.pntd.0005720] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 07/12/2017] [Accepted: 06/16/2017] [Indexed: 12/18/2022] Open
Abstract
Parasitic diseases caused by kinetoplastid parasites of the genera Trypanosoma and Leishmania are an urgent public health crisis in the developing world. These closely related species possess a number of multimeric enzymes in highly conserved pathways involved in vital functions, such as redox homeostasis and nucleotide synthesis. Computational alanine scanning of these protein-protein interfaces has revealed a host of potentially ligandable sites on several established and emerging anti-parasitic drug targets. Analysis of interfaces with multiple clustered hotspots has suggested several potentially inhibitable protein-protein interactions that may have been overlooked by previous large-scale analyses focusing solely on secondary structure. These protein-protein interactions provide a promising lead for the development of new peptide and macrocycle inhibitors of these enzymes.
Collapse
Affiliation(s)
- Leah M. Wachsmuth
- Department of Chemistry, Dickinson College, Carlisle, Pennsylvania, United States of America
| | - Meredith G. Johnson
- Department of Chemistry, Dickinson College, Carlisle, Pennsylvania, United States of America
| | - Jason Gavenonis
- Department of Chemistry, Dickinson College, Carlisle, Pennsylvania, United States of America
- * E-mail:
| |
Collapse
|
5
|
Leija C, Rijo-Ferreira F, Kinch LN, Grishin NV, Nischan N, Kohler JJ, Hu Z, Phillips MA. Pyrimidine Salvage Enzymes Are Essential for De Novo Biosynthesis of Deoxypyrimidine Nucleotides in Trypanosoma brucei. PLoS Pathog 2016; 12:e1006010. [PMID: 27820863 PMCID: PMC5098729 DOI: 10.1371/journal.ppat.1006010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 10/18/2016] [Indexed: 01/17/2023] Open
Abstract
The human pathogenic parasite Trypanosoma brucei possess both de novo and salvage routes for the biosynthesis of pyrimidine nucleotides. Consequently, they do not require salvageable pyrimidines for growth. Thymidine kinase (TK) catalyzes the formation of dTMP and dUMP and is one of several salvage enzymes that appear redundant to the de novo pathway. Surprisingly, we show through analysis of TK conditional null and RNAi cells that TK is essential for growth and for infectivity in a mouse model, and that a catalytically active enzyme is required for its function. Unlike humans, T. brucei and all other kinetoplastids lack dCMP deaminase (DCTD), which provides an alternative route to dUMP formation. Ectopic expression of human DCTD resulted in full rescue of the RNAi growth phenotype and allowed for selection of viable TK null cells. Metabolite profiling by LC-MS/MS revealed a buildup of deoxypyrimidine nucleosides in TK depleted cells. Knockout of cytidine deaminase (CDA), which converts deoxycytidine to deoxyuridine led to thymidine/deoxyuridine auxotrophy. These unexpected results suggested that T. brucei encodes an unidentified 5'-nucleotidase that converts deoxypyrimidine nucleotides to their corresponding nucleosides, leading to their dead-end buildup in TK depleted cells at the expense of dTTP pools. Bioinformatics analysis identified several potential candidate genes that could encode 5'-nucleotidase activity including an HD-domain protein that we show catalyzes dephosphorylation of deoxyribonucleotide 5'-monophosphates. We conclude that TK is essential for synthesis of thymine nucleotides regardless of whether the nucleoside precursors originate from the de novo pathway or through salvage. Reliance on TK in the absence of DCTD may be a shared vulnerability among trypanosomatids and may provide a unique opportunity to selectively target a diverse group of pathogenic single-celled eukaryotes with a single drug.
Collapse
Affiliation(s)
- Christopher Leija
- Department of Pharmacology University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Filipa Rijo-Ferreira
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Department of Neuroscience, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
- Graduate Program in Areas of Basic and Applied Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Lisa N. Kinch
- Department of Biophysics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Nick V. Grishin
- Department of Biophysics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Nicole Nischan
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Jennifer J. Kohler
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Zeping Hu
- Children’s Medical Center Research Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Margaret A. Phillips
- Department of Pharmacology University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| |
Collapse
|
6
|
Leroux AE, Krauth-Siegel RL. Thiol redox biology of trypanosomatids and potential targets for chemotherapy. Mol Biochem Parasitol 2016; 206:67-74. [DOI: 10.1016/j.molbiopara.2015.11.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/09/2015] [Accepted: 11/18/2015] [Indexed: 02/08/2023]
|
7
|
Nguyen S, Leija C, Kinch L, Regmi S, Li Q, Grishin NV, Phillips MA. Deoxyhypusine Modification of Eukaryotic Translation Initiation Factor 5A (eIF5A) Is Essential for Trypanosoma brucei Growth and for Expression of Polyprolyl-containing Proteins. J Biol Chem 2015; 290:19987-98. [PMID: 26082486 PMCID: PMC4528157 DOI: 10.1074/jbc.m115.656785] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 05/18/2015] [Indexed: 11/06/2022] Open
Abstract
The eukaryotic protozoan parasite Trypanosoma brucei is the causative agent of human African trypanosomiasis. Polyamine biosynthesis is essential in T. brucei, and the polyamine spermidine is required for synthesis of a novel cofactor called trypanothione and for deoxyhypusine modification of eukaryotic translation initiation factor 5A (eIF5A). eIF5A promotes translation of proteins containing polyprolyl tracts in mammals and yeast. To evaluate the function of eIF5A in T. brucei, we used RNA interference (RNAi) to knock down eIF5A levels and found that it is essential for T. brucei growth. The RNAi-induced growth defect was complemented by expression of wild-type human eIF5A but not by a Lys-50 mutant that blocks modification by deoxyhypusine. Bioinformatics analysis showed that 15% of the T. brucei proteome contains 3 or more consecutive prolines and that actin-related proteins and cysteine proteases were highly enriched in the group. Steady-state protein levels of representative proteins containing 9 consecutive prolines that are involved in actin assembly (formin and CAP/Srv2p) were significantly reduced by knockdown of eIF5A. Several T. brucei polyprolyl proteins are involved in flagellar assembly. Knockdown of TbeIF5A led to abnormal cell morphologies and detached flagella, suggesting that eIF5A is important for translation of proteins needed for these processes. Potential specialized functions for eIF5A in T. brucei in translation of variable surface glycoproteins were also uncovered. Inhibitors of deoxyhypusination would be expected to cause a pleomorphic effect on multiple cell processes, suggesting that deoxyhypusine/hypusine biosynthesis could be a promising drug target in not just T. brucei but in other eukaryotic pathogens.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Flagella/genetics
- Flagella/metabolism
- Flagella/ultrastructure
- Gene Knockdown Techniques
- Humans
- Lysine/analogs & derivatives
- Lysine/metabolism
- Microfilament Proteins/genetics
- Microfilament Proteins/metabolism
- Molecular Sequence Data
- Peptide Initiation Factors/antagonists & inhibitors
- Peptide Initiation Factors/genetics
- Peptide Initiation Factors/metabolism
- Peptides/metabolism
- Protein Processing, Post-Translational
- Proteome/genetics
- Proteome/metabolism
- Protozoan Proteins/antagonists & inhibitors
- Protozoan Proteins/genetics
- Protozoan Proteins/metabolism
- RNA, Messenger/antagonists & inhibitors
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Protozoan/antagonists & inhibitors
- RNA, Protozoan/genetics
- RNA, Protozoan/metabolism
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- RNA-Binding Proteins/antagonists & inhibitors
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Sequence Alignment
- Sequence Homology, Amino Acid
- Trypanosoma brucei brucei/genetics
- Trypanosoma brucei brucei/metabolism
- Trypanosoma brucei brucei/ultrastructure
- Eukaryotic Translation Initiation Factor 5A
Collapse
Affiliation(s)
| | | | | | | | - Qiong Li
- From the Departments of Pharmacology and
| | - Nick V Grishin
- Biophysics and Biochemistry and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041
| | | |
Collapse
|
8
|
Haanstra JR, Bakker BM. Drug target identification through systems biology. DRUG DISCOVERY TODAY. TECHNOLOGIES 2015; 15:17-22. [PMID: 26464086 DOI: 10.1016/j.ddtec.2015.06.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 05/18/2015] [Accepted: 06/12/2015] [Indexed: 06/05/2023]
Abstract
To rationalise drug target selection, we should understand the role of putative targets in biological pathways quantitatively. We review here how experimental and computational network-based approaches can aid more rational drug target selection and illustrate this with results obtained for microbes and for cancer. Comparison of the drug response of biochemical networks in target cells and (healthy) host cells can reveal network-selective targets.
Collapse
Affiliation(s)
- Jurgen R Haanstra
- Department of Pediatrics and Systems Biology Centre for Energy Metabolism and Ageing, University of Groningen, University Medical Center Groningen, The Netherlands; Department of Molecular Cell Physiology, Vrije Universiteit Amsterdam, The Netherlands.
| | - Barbara M Bakker
- Department of Pediatrics and Systems Biology Centre for Energy Metabolism and Ageing, University of Groningen, University Medical Center Groningen, The Netherlands; Department of Molecular Cell Physiology, Vrije Universiteit Amsterdam, The Netherlands
| |
Collapse
|
9
|
Li Q, Leija C, Rijo-Ferreira F, Chen J, Cestari I, Stuart K, Tu BP, Phillips MA. GMP synthase is essential for viability and infectivity of Trypanosoma brucei despite a redundant purine salvage pathway. Mol Microbiol 2015; 97:1006-20. [PMID: 26043892 DOI: 10.1111/mmi.13083] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2015] [Indexed: 12/28/2022]
Abstract
The causative agent of human African trypanosomiasis, Trypanosoma brucei, lacks de novo purine biosynthesis and depends on purine salvage from the host. The purine salvage pathway is redundant and contains two routes to guanosine-5'-monophosphate (GMP) formation: conversion from xanthosine-5'-monophosphate (XMP) by GMP synthase (GMPS) or direct salvage of guanine by hypoxanthine-guanine phosphoribosyltransferase (HGPRT). We show recombinant T. brucei GMPS efficiently catalyzes GMP formation. Genetic knockout of GMPS in bloodstream parasites led to depletion of guanine nucleotide pools and was lethal. Growth of gmps null cells was only rescued by supraphysiological guanine concentrations (100 μM) or by expression of an extrachromosomal copy of GMPS. Hypoxanthine was a competitive inhibitor of guanine rescue, consistent with a common uptake/metabolic conversion mechanism. In mice, gmps null parasites were unable to establish an infection demonstrating that GMPS is essential for virulence and that plasma guanine is insufficient to support parasite purine requirements. These data validate GMPS as a potential therapeutic target for treatment of human African trypanosomiasis. The ability to strategically inhibit key metabolic enzymes in the purine pathway unexpectedly bypasses its functional redundancy by exploiting both the nature of pathway flux and the limited nutrient environment of the parasite's extracellular niche.
Collapse
Affiliation(s)
- Qiong Li
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA
| | - Christopher Leija
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA
| | - Filipa Rijo-Ferreira
- Department of Neuroscience, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA.,Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.,Graduate Program in Areas of Basic and Applied Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Jun Chen
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA
| | - Igor Cestari
- Seattle Biomedical Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, WA, 98109-5219, USA
| | - Kenneth Stuart
- Seattle Biomedical Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, WA, 98109-5219, USA
| | - Benjamin P Tu
- Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA
| | - Margaret A Phillips
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Rd, Dallas, TX, 75390-9041, USA
| |
Collapse
|