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Essays in Biochemistry

Molecular Parasitology

Edited by R. Docampo

Series EditorMelanie Welham (U.K.)

Advisory BoardG. Banting (U.K.)E. Blair (U.K.)C. Cooper (U.K.)N. Hooper (U.K.)W. Jessup (Australia)J. Pearson (U.K.)J. Rossjohn (Australia)S. Shears (U.S.A.)E. Shephard (U.K.)J. Tavaré (U.K.)

volume 51 2011

Essays in Biochemistry is published by Portland Press Limited on behalf of the Biochemical Society

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© The Authors; Journal compilation © 2011 Biochemical Society

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Typeset by Aptara Inc., New Delhi, IndiaPrinted in Great Britain by Henry Ling Limited, Dorchester

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Contents

Preface ............................................................................................. xi

Authors .......................................................................................... xiii

Abbreviations ................................................................................ xix

1 Molecular parasitology in the 21st Century .................................. 1Roberto Docampo

Abstract .................................................................................................................... 1Introduction ............................................................................................................ 1Trypanosomatids .................................................................................................... 4Apicomplexan parasites ........................................................................................ 7Amitochondriate protists ..................................................................................... 9Conclusions ...........................................................................................................10Summary ................................................................................................................10References .............................................................................................................10

2 Glucose metabolism in Trypanosoma cruzi .................................. 15Dante A. Maugeri, Joaquin J.B. Cannata and Juan‑José Cazzulo

Abstract ..................................................................................................................15Introduction ..........................................................................................................15Glucose uptake .....................................................................................................16Aerobic fermentation of glucose ......................................................................17Glycolytic pathway ...............................................................................................17PPP ...........................................................................................................................23Other aspects of glucose metabolism .............................................................26Conclusions ...........................................................................................................27Summary ................................................................................................................27References .............................................................................................................27

3 Gene expression regulation in trypanosomatids ........................ 31Javier G. De Gaudenzi, Griselda Noé, Vanina A. Campo, Alberto C. Frasch and Alejandro Cassola

Abstract ..................................................................................................................31Introduction ..........................................................................................................32Genes, transcription and RNA processing.....................................................32

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mRNA turnover and RNA-binding domain proteins ..................................36Regulating mRNA translation ............................................................................39Co-regulation of transcripts encoding proteins with related functions ......41Conclusions ...........................................................................................................43Summary ................................................................................................................43References .............................................................................................................44

4 African trypanosomes: the genome and adaptations for immune evasion ............................................................................. 47

Gloria Rudenko

Abstract ..................................................................................................................47Introduction ..........................................................................................................48Trypanosome cell biology and immune evasion ...........................................48Changing the active VSG ....................................................................................51The VSG repertoire ............................................................................................53The unusual architecture of the trypanosome genome ..............................54VSG expression sites ............................................................................................55Epigenetics and VSG expression site control .................................................56Conclusions and future goals ............................................................................58Summary ................................................................................................................58References .............................................................................................................59

5 Folate metabolic pathways in Leishmania ................................... 63Tim J. Vickers and Stephen M. Beverley

Abstract ..................................................................................................................63Introduction ..........................................................................................................64Acquisition of folates and pteridines ...............................................................65Activation of folate to tetrahydrofolate by DHFR and PTR1 ....................70Synthesis of methionine requires methyl-H4F: a non-essential pathway? .................................................................................................................7410-CHO-THF: the second critical form of C1-folate ..................................75Novel roles for folates in Leishmania: YGFZ and iron–sulfur cluster protein function ....................................................................................................76Conclusion and future studies ..........................................................................77Summary ................................................................................................................77References .............................................................................................................78

6 Intracellular growth and pathogenesis of Leishmania parasites ...................................................................... 81

Thomas Naderer and Malcolm J. McConville

Abstract ..................................................................................................................81Introduction ..........................................................................................................82

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Genes required for parasite survival in macrophages .................................85Genes required for lesion formation ..............................................................91Genes involved in induction of visceral disease ............................................91Conclusions ...........................................................................................................92Summary ................................................................................................................93References .............................................................................................................93

7 Calcium storage and function in apicomplexan parasites ......... 97Silvia N.J. Moreno, Lawrence Ayong and Douglas A. Pace

Abstract ..................................................................................................................97Introduction ..........................................................................................................98Ca2+ homoeostasis and storage in apicomplexans .......................................98Calcium signalling and functions in apicomplexan parasites .....................102CBPs in apicomplexan parasites .....................................................................103Functional studies of calcium and CBPs in apicomplexan parasites .......104Conclusions .........................................................................................................106Summary ..............................................................................................................107References ...........................................................................................................107

8 The apicoplast: a red alga in human parasites .......................... 111Boris Striepen

Abstract ................................................................................................................111Apicomplexa are important pathogens .........................................................112A small step for an alga – a giant leap for the tree of life .........................112Why does a parasite need a chloroplast? .....................................................113Discovering the metabolic functions of the apicoplast .............................115The apicoplast is an anabolic hub ...................................................................118The apicoplast is fed from the cytoplasm.....................................................119Apicoplast proteins are largely not encoded on the apicoplast genome .................................................................................................................120Conclusions .........................................................................................................123Summary ..............................................................................................................123References ...........................................................................................................124

9 Metamorphoses of malaria: the role of autophagy in parasite differentiation ................................................................ 127

Isabelle Coppens

Abstract ................................................................................................................127Introduction: adaptation of Plasmodium to the hepatic environment ........................................................................................................128

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Contents © 2011 Biochemical Society

Autophagic removal of organelles ..................................................................129Critical role of autophagy for protozoan parasite development ............131Autophagic activities in the malaria parasite ................................................132Conclusions .........................................................................................................134Summary ..............................................................................................................134References ...........................................................................................................135

10 Malaria drug resistance: new observations and developments ............................................................................... 137

Juliana M. Sá, Jason L. Chong and Thomas E. Wellems

Abstract ................................................................................................................137Birth of antimalarial treatments east and west: qinghaosu and cinchona ...............................................................................................................138From cinchona alkaloids to synthetic antimalarials ....................................138Antimalarials from synthetic chemistry ........................................................140ART, its derivatives and endoperoxide analogues .....................................141Plasmodium parasites respond: ATB resistance ...........................................142Rise and fall of CQ and AQ .............................................................................143ART tolerance: harbinger of resistance? ......................................................149Drug-resistant P. vivax .......................................................................................150Perspectives .........................................................................................................151Summary ..............................................................................................................153References ...........................................................................................................154

11 Trichomonas vaginalis: current understanding of host–parasite interactions ........................................................... 161

Christopher M. Ryan, Natalia de Miguel and Patricia J. Johnson

Abstract ................................................................................................................161Introduction ........................................................................................................162Trichomonas adhesion ........................................................................................163Adhesion molecules ..........................................................................................163Proteomic approaches to address pathogenesis ........................................168Conclusions .........................................................................................................171Note added in proof .........................................................................................172Summary ..............................................................................................................172References ...........................................................................................................173

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12 Mechanisms of adaptation in the intestinal parasite Giardia lamblia .............................................................................. 177

Hugo D. Lujan

Abstract ................................................................................................................177Introduction ........................................................................................................178Giardia differentiation into cysts .....................................................................180Antigenic variation in Giardia ...........................................................................185Conclusions .........................................................................................................188Summary ..............................................................................................................189References ...........................................................................................................190

13 The ways of a killer: how does Entamoeba histolytica elicit host cell death? ............................................................................. 193

Katherine S. Ralston and William A. Petri, Jr

Abstract ................................................................................................................193Introduction ........................................................................................................194Disease pathogenesis ........................................................................................195Mechanism of cytotoxicity ...............................................................................196What are the cytotoxic effectors? .................................................................202Conclusions .........................................................................................................207Summary ..............................................................................................................207References ...........................................................................................................208

Index .............................................................................................. 211

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Preface

Molecular parasitology has been defined as the study of parasites and their interactions with their host at the molecular level. This study is relevant not only because a thorough understanding of the parasites and their interactions with their hosts could lead to the development of new chemotherapeutic agents, diagnostic methods and vaccines, but also because parasites exhibit unusual biological characteristics that could help us understand the evolution of biological processes. Half of the human population and an even greater number of domestic and wild animals are infected with parasites, and the aim of this volume is to present an overview of the most recent molecular work on the most important human protist parasites.

The volume starts with my brief introduction discussing the peculiarities of protist parasites and the molecular tools available to work in molecular parasitology (Chapter 1) and is then divided broadly into three sections. The next five chapters are about trypanosomatids, followed by four chapters on apicomplexan parasites, and the final three chapters concern amitochondri-ate protists. The chapters on trypanosomatids cover aspects that have been the subject of considerable research interest in these parasites. Cazzulo and colleagues (Chapter 2) examine glucose metabolism in Trypanosoma cruzi. This pathway is characterized by the absence of a Pasteur effect (a decrease in glucose utilization under aerobic conditions) and by the presence of glycosomes containing several of the glycolytic enzymes, a peculiarity com-mon to all trypanosomatids. De Gaudenzi and colleagues (Chapter 3) consider the unusual mechanisms of gene expression in trypanosomatids, including polycistronic transcription, and the post-transcriptional regulation of gene expression. Rudenko (Chapter 4) discusses the mechanism of antigenic vari-ation of the variant surface glycoprotein coat in African trypanosomes, a pro-cess by which these trypanosomes can escape from the immune system of their hosts. Vickers and Beverley (Chapter 5) examine the folate metabolic pathway in Leishmania, a source of numerous opportunities for targeted chemotherapy. Finally, Naderer and McConville (Chapter 6) describe the genes of Leishmania spp. involved in protection against various stresses to which these parasites are submitted while in their intracellular habitat within the macrophage, and their virulence determinants.

Apicomplexan parasites are considered in subsequent chapters. Calcium is important for a number of functions in apicomplexan parasites, such as motility, secretion, invasion, egress and differentiation, and Moreno and colleagues (Chapter 7) examine its roles. This chapter also discusses two calcium-containing organelles that have been identified recently, the

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Preface © 2011 Biochemical Society

acidocalcisome and the plant-like vacuole. Apicomplexan parasites are charac-terized by the presence of other novel organelles, and the apicoplast, which is a chloroplast-like organelle, is the subject of the chapter by Striepen (Chapter 8). The apicoplast is essential and is home to various synthesis pathways, which are distinct from their human counterparts and therefore good targets for drug development. Coppens (Chapter 9) describes the role of autophagy in differ-entiation of the sporozoites of malaria parasites, a process that is essential for the drastic metamorphoses of these life cycle stages. Finally, Wellems and col-leagues (Chapter 10) consider the history of malaria treatment, the emergence of drug resistance and the molecular mechanisms involved in these processes.

The preceding chapters on trypanosomatids and apicomplexan parasites lead into the final three chapters on amitochondriate protists. Johnson and colleagues (Chapter 11) examine recent work on the molecules involved in adhesion of Trichomonas vaginalis to mammalian cells and the secreted pro-teins identified by proteomic approaches that are involved in its pathogenesis. Lujan (Chapter 12) discusses the mechanisms of adaptation of Giardia lamblia to its host, the process of encystation, the phenomenon of antigenic variation that helps the parasite to evade the immune response and the role of the RNA interference pathway in its regulation. Finally, in Chapter 13, Ralston and Petri provide an overview of the mechanisms used by Entamoeba histolytica to attach to the host cells and elicit host cell death by apoptosis.

I would like to take this opportunity to thank all of the authors for their considerable efforts. I am also very grateful to the many reviewers for tak-ing the time to provide constructive criticism and suggestions. I apologize to those whose work could not be properly cited because of space limitations. My thanks also to Clare Curtis and Portland Press Limited for their work in ensuring the high quality of this book.

Roberto DocampoAthens, GA, U.S.A.

May 2011

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Authors

Roberto Docampo obtained an M.D. and a Ph.D. in Biological Chemistry from the University of Buenos Aires, Argentina, and a Ph.D. in Microbiology from the Federal University of Rio de Janeiro, Brazil. After several years as Professor of Pathobiology at the University of Illinois at Urbana-Champaign, IL, U.S.A., he became Professor of Cellular Biology and Eminent Scholar at the University of Georgia, Athens, GA, U.S.A. His laboratory identified the acidocalcisome, an organelle present in a wide range of organisms from bacteria to humans. His research team focuses on the role of this organelle and of polyphosphate in parasites and other organisms.

Juan-José Cazzulo has a Ph.D. in Biochemistry from the University of Cordoba, Argentina, and an honorary Doctor of Medicine degree from the University of Uppsala, Sweden. He was a postdoctoral fellow at the University of Leicester, U.K., under the direction of Hans Kornberg (1968–1970). He is a professor of Biochemistry and a senior researcher at the Instituto de Investigaciones Biotecnológicas, National University of San Martín, Argentina. He has been President of the Argentinian Biochemical Society (SAIB), Chairman of the Pan-American Association for Biochemistry and Molecular Biology (PABMB) and a member of the International Union of Biochemistry and Molecular Biology (IUBMB). His research interests include the study of carbohydrate, amino acid and protein metabolism in trypanosomatids. Joaquin Cannata has a Ph.D. in Chemistry from the University of Buenos Aires, Argentina. He was a postdoctoral fellow at New York University, NY, U.S.A., under the direction of Severo Ochoa, from 1963 to 1965. He is a professor of Biochemistry and a researcher from the Argentinian National Research Council (CONICET), working at the Instituto de Investigaciones Biotecnológicas, National University of San Martín (IIB-INTECH, UNSAM-CONICET). His research interests centre on the study of carbohydrate metabolism in Trypanosoma cruzi. Dante Maugeri has a Ph.D. in Biochemistry from the University of Buenos Aires, Argentina. He is an assistant professor at the Instituto de Investigaciones Biotecnológicas, National University of San Martín (IIB-INTECH, UNSAM-CONICET). His research interests include the study of energy metabolism in trypano-somatids, as well as the regulatory properties of phosphoenolpyruvate carboxykinase in T. cruzi.

Javier De Gaudenzi is a researcher from the Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Buenos Aires, Argentina. He received a Ph.D. in Molecular Biology and Biotechnology in 2007 from the University of San Martín, Argentina. From 2008 to 2009 he

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Authors © The Authors Journal compilation © 2011 Biochemical Society

carried out postdoctoral research studying RNA-binding proteins and RNA–protein interactions in trypanosomes. Griselda Noé has recently received her Ph.D. in Molecular Biology and Biotechnology from the University of San Martín. Her research has focused on RNA–protein interactions and their func-tion within post-transcriptional operons in trypanosomes. She is currently a research fellow from the CONICET, Argentina. Vanina Campo received her Ph.D. in 2005, working in Alberto Frasch’s laboratory studying the genes, pseudogenes and proteins of a large variable family of surface mucins expressed in T. cruzi infective forms. Between 2006 and 2009, she did carried out postdoctoral research studying the molecular mechanisms of mutation for the generation of antibody diversity at the Institute for Clinical Research in Montreal, Canada. She returned to the Frasch laboratory in 2010 to study the regulation of gene expression mediated by post-transcriptional trans-splicing events in T. cruzi. Alberto Frasch is the director of the Institute for Research in Biotechnology, University of San Martín, a professor at the University of San Martín and a CONICET researcher. He received a Ph.D. in Cell Biology in 1977 from the University of Buenos Aires. He did postdoctoral work in The Netherlands at the University of Amsterdam and in the U.S. at the University of Oregon. In 2006, he was elected a foreign associate of the National Academy of Sciences, U.S.A. His research interest is the post-transcriptional regulation of gene expression in trypanosomes. Alejandro Cassola received his Ph.D. from the University of San Martín. His research has focused on analysing mRNA metabolism reprogramming in trypanosomes, in particular, the formation of ribonucleoprotein granules during environmental changes, as well as nucleocytoplasmic shuttling of RNA-binding proteins. He is currently a CONICET research fellow.

Gloria Rudenko grew up in San Francisco, U.S.A., and moved to The Netherlands to study Biochemistry (University of Leiden), before joining the Department of Genetics, Columbia University, New York, NY, U.S.A., as a Ph.D. student. She returned to Amsterdam for postdoctoral research (Netherlands Cancer Institute, Amsterdam). Subsequently, she joined the Department of Biochemistry (The Peter Medawar Building for Pathogen Research) at the University of Oxford as a Wellcome Trust Senior Fellow in Basic Biomedical Sciences. Her research group is currently located in the Division of Cell and Molecular Biology at Imperial College London, U.K., where it investigates molecular mechanisms of antigenic variation in Trypanosoma brucei.

Tim Vickers did his undergraduate degree at Dundee University, Scotland, U.K. He completed his Ph.D. on the thiol metabolism and drug resistance of trypanosomes and Leishmania in 2004, under the supervision of Alan Fairlamb. He then moved to the U.S.A. and is currently working at Washington University in St Louis, in Steve Beverley’s laboratory. His interests centre on Leishmania folate and pteridine metabolism, as well as the development of improved genetic tools for the analysis of essential enzymes,

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with the aim of aiding the development of drugs targeted to these proteins. Stephen Beverley is Chair of the Department of Molecular Microbiology at Washington University School of Medicine in St Louis. He began the study of gene amplification and antifolate drug resistance in Leishmania while a post-doctoral fellow at Stanford University, and continued these studies at Harvard Medical School, rising to the rank of Professor and Acting Chair of Biological Chemistry and Molecular Pharmacology. In 1997 he moved to St Louis where the focus has turned to understanding pteridine metabolic pathways and their role in Leishmania infectivity. He has published over 200 papers in scholarly journals on this and related areas of Leishmania molecular genetics.

Malcolm McConville is a professor in the Department of Biochemistry and Molecular Biology, University of Melbourne, Australia. His research has focused on understanding the molecular basis of microbial pathogen-esis, particularly with regard to Leishmania parasites. His research group has played a key role in defining the structure, function and biosynthetic pathways for the major surface glycoconjugates of these parasites, as well as aspects of central carbon metabolism that are required for Leishmania viru-lence. He is currently establishing a major analytical facility at the University of Melbourne for metabolomic analysis of intracellular pathogens. Thomas Naderer is a postdoctoral fellow in the Department of Biochemistry and Molecular Biology, University of Melbourne. Over the last decade, he has developed novel tools for the isolation of cell-surface mutants, investigated intracellular storage carbohydrates and identified novel metabolic path-ways important in Leishmania virulence. By generating various metabolic Leishmania mutants, he has highlighted novel pathways of nutrient scaveng-ing in the parasite–host relationship. He is also particularly interested in how Leishmania copes with temperature stress during mammalian infection and how this environmental cue translates into stage differentiation.

Silvia Moreno obtained her Ph.D. in Biochemistry from the University of Buenos Aires, Argentina, and carried out postdoctoral work at the NIH (National Institutes of Health) and The Rockefeller University. After several years as Professor of Parasitology at the University of Illinois at Urbana-Champaign, U.S.A., she became Professor of Cellular Biology at the University of Georgia, Athens, GA, U.S.A. Her laboratory identified the acidocalcisome and, more recently, the plant-like vacuole of T. gondii. Her research team focuses on the role of these organelles in apicompl-exan parasites and in cell signalling in T. cruzi. Lawrence Ayong earned his Ph.D. in Biomolecular Science from the University of Central Florida, U.S.A., and is currently a postdoctoral fellow at the Center for Tropical and Emerging Global Diseases, University of Georgia, Athens. His research focus is on membrane biogenesis and vesicle trafficking in apicomplexan parasites. His background includes 5 years of undergraduate teaching experience, a Fulbright Fellowship and the authorship of several peer-reviewed articles.

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Douglas Pace completed his Ph.D. in Biological Sciences at the University of Southern California, U.S.A. He is currently an NIH postdoctoral fel-low at the Center for Tropical and Emerging Global Diseases, University of Georgia, Athens. He studies the molecular physiology of apicomplexan para-sites. Specific research interests include the characterization of aquaporin water channels and ion regulation in T. gondii.

Boris Striepen received academic training at the universities of Bonn and Marburg, Germany. As a doctoral student in Marburg he chararterized para-site glycoconjugates with Ralph Schwarz, and then moved to Philadelphia, U.S.A., to work with David Roos on parasite cell biology. Since 2000 he has been a faculty member of the University of Georgia in Athens, U.S.A., where he is currently a professor of Cellular Biology and a GRA (Georgia Research Alliance) Distinguished Investigator. His research group uses Toxoplasma gondii as a genetic model to understand parasite cell biology and metabolism. Currently, he also serves as a director for the MBL Biology of Parasitism summer course in Woods Hole, MA, U.S.A.

Isabelle Coppens has been a faculty member of the Department of Molecular Microbiology and Immunology at the Johns Hopkins University School of Public Health, U.S.A., and of the Bloomberg Malaria Research Institute, since 2003. Her laboratory is conducting research on the mechanisms of intracellular adaptations of apicomplexan parasites to their hosts. The pathogens studied in her research include Plasmodium, Toxoplasma and Cryptosporidium.

Juliana Sá received her B.S. degree in Biology at São Paulo State University, Brazil, in 1999. She earned an M.S. degree in 2001 investigating the relationship between structure and function of enzymes from snake venoms under supervision of Richard Ward at the University of São Paulo, Brazil. Seeking to apply her structural biology knowledge to infectious diseases and to improve her molecular biology skills, she completed her Ph.D. in 2005, investigating the mechanism of Plasmodium vivax chloroquine resis-tance under supervision of Hernando del Portillo at the University of São Paulo. Fascinated by the biological phenomenon of parasite drug resistance development, she joined Thomas Wellems’ group in 2005, where she is cur-rently a research fellow investigating the genetics of P. falciparum and P. vivax 4-aminoquinoline resistance in the Laboratory of Malaria and Vector Research, NIAID (National Institute of Allergy and Infectious Diseases), NIH. Jason Chong completed his B.S. (Hons) degree in Biology at the University of North Carolina at Chapel Hill, U.S.A., in 1999. He completed his Ph.D. in 2009 at Northwestern University, where he studied mammalian circadian rhythms in the laboratory of Joseph Takahashi. He is currently a postdoctoral fellow studying the genetic basis of artemisinin resistance in Plasmodium falciparum in Thomas Wellems’ group in the Laboratory of Malaria and Vector Research, NIAID, NIH. Thomas Wellems received his M.D. and Ph.D. from the University of Chicago, U.S.A. He completed his

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internal medicine residency at the Hospital of the University of Pennsylvania and in 1984 he joined NIAID’s Division of Intramural Research. He has directed the Malaria Genetics Section since 1991 and has served as Chief of the Laboratory of Malaria and Vector Research since 2002. He is a member of the U.S. National Academy of Sciences and the Institute of Medicine, is a past president of the American Society of Tropical Medicine and Hygiene, and has served on a number of advisory committees for foundations and public/private partnerships, including the Medicines for Malaria Venture.

Patricia Johnson is a professor of Microbiology, Immunology and Molecular Genetics at The University of California, Los Angeles, U.S.A., where she studies the human-infective parasite Trichomonas vaginalis. She received her Ph.D. from the University of Michigan, U.S.A., and conducted postdoctoral research at the Netherlands Cancer Institute, studying the African trypanosome, and The Rockefeller University, U.S.A., where she began her research on Trichomonas. She is the recipient of a Helen Hay Whitney Postdoctoral Fellowship, an Investigator Award from the National Foundation for Infectious Diseases, a New Investigator Award and a Scholar Award from the Burroughs Wellcome Fund and a MERIT Award from the NIH. She has served as the director of the Biology of Parasitism summer course at the MBL (Marine Biological Laboratories) at Woods Hole, MA, U.S.A., and as a member of the NIH Tropical Medicine and Parasitology Study Section. She is currently an Associate Editor of PLoS Pathogens and mBio and was elected to the American Academy of Microbiology in 2011. Natalia de Miguel is a postdoctoral scholar at University of California, Los Angeles, U.S.A., studying the pathogenesis of T. vaginalis. She received her Ph.D. in Molecular Biology and Biotechnology from the Universidad Nacional General San Martín, Argentina, where she studied a family of heat-shock proteins in the parasite Toxoplasma gondii. During her Ph.D. studies, she received a travel grant from Boehringer Ingelheim Fonds and Wood-Whelan Research Fellowships to work as a visiting scientist at the University of Montpellier, France. She is the recipient of an international post-doctoral fellowship from the American Association of University Women. Christopher Ryan is a postdoctoral scholar at the University of California, Los Angeles where he studies the pathogenesis of T. vaginalis. He received his Ph.D. in Molecular Parasitology from the State University of New York at Buffalo, U.S.A.. His thesis was awarded the School of Medicine and Biomedical Sciences Dean’s Award for outstanding dissertation research. He is the recipient of a postdoctoral fellowship from the American Cancer Society. He also received a travel grant from Boehringer Ingelheim Fonds to work as a visiting scientist at the University of Dundee, Scotland, U.K.

Hugo Lujan received his Ph.D. in Biochemistry from the School of Chemistry, National University of Cordoba, Argentina, in 1991. He carried out postdoctoral work in the U.S. at the National Institute of Allergy and

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Infectious Diseases, NIH, until 1996. Currently, he is a full professor of Biochemistry and Molecular Biology at the School of Medicine, Catholic University of Cordoba, and a Principal Investigator of the National Research Council of Argentina. He is also an international research scholar of the Howard Hughes Medical Institute, U.S.A., and a fellow of the John Simon Guggenheim Memorial Foundation. During most of his research career he has been studying the molecular mechanism of Giardia adaptation and differentiation.

Katherine Ralston has had a long-standing interest in host–pathogen interactions and is currently a postdoctoral fellow studying the cytotoxic mechanism of Entamoeba histolytica in the laboratory of William Petri, Jr, at the University of Virginia, U.S.A. Her undergraduate research at the University of California, Davis focused on cell-to-cell movement of Lettuce infectious yellows virus, and her dissertation research at the University of California, Los Angeles focused on flagellar motility in T. brucei, which is central to the pathogenesis of African sleeping sickness. She identified a key regulator of flagellar dynein motors and also discovered that, surpris-ingly, flagellar motility contributes to cell division in T. brucei. She is the recipient of a Howard Hughes Medical Institute postdoctoral fellowship from the Life Sciences Research Foundation and an individual postdoc-toral fellowship from the NIH. She has been recognized with outstanding poster and talk awards for her work on E. histolytica and T. brucei, a Distinction in Teaching award at the University of California, Los Angeles and an Outstanding Senior award at the University of California, Davis. William Petri, Jr, is a practising physician and teacher who has dedicated his investigative career to the study of global health, focusing on diarrhoea in infants and children. He identified the Gal/GalNAc-binding lectin of the enteric parasite E. histolytica required for contact-dependent killing of host cells. He showed that it binds the parasite to the human colon and enables the amoebae to evade human complement. He pioneered DNA transform-ation of the parasite, and validated in vivo the lectin’s role in pathogenesis. Clinically, he developed FDA (Food and Drug Administration)-approved antigen-detection tests that allow sensitive and specific diagnosis of amoebiasis. Using these tests in a now 10 year study of 300 children in Bangladesh, he discovered that 10% of study children developed amoebic disease annually, which was associated with both malnutrition and cog-nitive dysfunction. Acquired immunity was identified and associated with interferon γ and mucosal IgA anti-lectin antibody. A genetic polymorphism in the leptin receptor influenced the development of immunity. On the basis of this laboratory and field work, he is now developing a Gal/GalNAc lectin-based amoebiasis vaccine and exploring the impact of diarrhoea on malnutrition and oral vaccine failure.

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© 2011 Biochemical SocietyAbbreviations

ABC ATP-binding cassetteACP acyl-carrier proteinACT artemesinin-combination therapyADH l-alanine dehydrogenaseAgo ArgonauteAP adhesion proteinAPT apicoplast phosphate translocatorAQ amodiaquineAQR AQ resistanceART artemisininATB atebrineATG autophagy-related geneBAPTA/AM 1,2-bis-(o-aminophenoxy)

ethane-N,N,N′,N′-tetra-acetic acid tetrakis(acetoxymethyl ester)

BHK baby hamster kidneyBiP immunoglobulin heavy-chain-binding

proteinBT biopterin transporterC1 one-carboncADPr cyclic adenosine diphosphate riboseCaM calmodulinCBL calcineurin B-likeCBP calcium-binding proteinCCaMK calcium/CaM-dependent protein kinaseCDPK calcium-dependent protein kinaseCH cyclohydrolaseChIP-seq chromatin immunoprecipitation and

sequencing10-CHO-H4F 10-formyltetrahydrofolateCML CaM-likeCP cysteine proteaseCPC cathepsin CCQ chloroquineCQR CQ resistanceCRD carbohydrate recognition domainCWP cyst wall proteinDH dehydrogenase

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DHCH methylene-H4F dehydrogenase/methenyl-H4F cyclohydrolase

DHFR dihydrofolate reductaseDHLDH dihydrolipoamide dehydrogenaseDOXP deoxy-xylulose phosphatedsRNA double-stranded RNAECM extracellular matrixEcYgfZ Escherichia coli YgfZEhCP5 Entamoeba histolytica cysteine protease 5EhSTIRP Entamoeba histolytica serine-, threonine-

and isoleucine-rich proteinEhTMKB1-9 Entamoeba histolytica transmembrane

kinase B1-9eIF eukaryotic initiation factorER endoplasmic reticulumERAD ER-associated degradationES expression siteESAG expression site-associated geneESB expression-site bodyESV encystation-specific secretory vesicleFASI fatty acid synthesis type IFASII fatty acid synthesis type IIFBT folate–biopterin transporterFCL 5-CHO-H4F cycloligaseFPGS folylpolyglutamate synthetase FT folate transporterFTL formyltetrahydrofolate ligasefura 2/AM, fura 2 acetoxymethyl esterG6PDH glucose-6-phosphate dehydrogenaseGal galactoseGalNAc N-acetylgalactosamineGAPDH glyceraldehyde-3-phosphate dehydrogenaseGCC glycine cleavage complexGFP green fluorescent proteinGIPL glycosylphosphatidylinositol lipidGK glucokinaseGlc glucoseGlcNAc N-acetylglucosamineGPI glycosylphosphatidylinositolGPN glycyl-l-phenylalanine-naphthylamideH2F dihydrofolateH4F (also called THF) tetrahydrofolateHK hexokinase

Abbreviations © 2011 Biochemical Society

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HSP heat-shock proteinICDH isocitrate dehydrogenaseIF translation-initiation factorIFA immunofluorescence assayIP3 inositol 1,4,5-trisphosphateIPP isopentenyl pyrophosphateKERP1 lysine- and glutamic acid-rich protein 1LPG lipophosphoglycanLTR long terminal repeat3-MA 3-methyladenineMAPK (also called MPK) mitogen-activated protein kinaseMAPKK (also called MPKK) MAPK kinaseMDAQ monodesethylamodiaquineMDCQ monodesethylchloroquineMDH malate dehydrogenasecMDH cytosolic MDH methylene H4F 5,10-CH2-tetrahydrofolateMetS methionyl-tRNA synthetasem7G 7-methyl guanosinemiRNA microRNAMLO mitochondrion-like organellemRNP messenger RNPMTHFR methylene-H4F reductaseMudPIT multidimensional protein identification

technologyNOS nitrosative speciesOSRD Office of Scientific Research and

DevelopmentOZ ozonideP bodies processing bodiespABA p-aminobenzoic acidPABP poly(A)-binding proteinPAO phenylarsine oxidePbATG Plasmodium berghei ATGPE phosphatidylethanolaminePEP phosphoenolpyruvatePEPCK PEP carboxykinasePex peroxisomal membrane proteinPfCRT Plasmodium falciparum chloroquine

resistance transporterPFK phosphofructokinase3PGA 3-phosphoglyceraldehyde

© 2011 Biochemical Society Abbreviations

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6PGDH 6-phosphogluconate dehydrogenasePgh P-glycoprotein homologue6-PGL 6-phosphogluconolactonasePI3K phosphatidylinositol 3-kinasePI3P phosphatidylinositol 3-phosphatePK pyruvate kinasePLC phospholipase CPI-PLC phosphoinositide PLCPLV (also called VAC) plant-like vacuolePMCA plasma membrane Ca2+-ATPasePPDK pyruvate-phosphate dikinasePPP pentose phosphate pathwayPQ primaquinepseDHCH2 DHCH pseudogenePTGS post-transcriptional gene silencingPTPase protein tyrosine phosphatasePTP1B PTPase 1BPTR pteridine reductasePTS1 peroxisomal targeting signal 1PUF/Puf Pumilio and Fem-3-binding factorPV parasitophorous vacuoleQDPR quinonoid dihydropteridine reductaseQN quinineRBP RNA-binding proteinRdRP RNA-dependent RNA polymeraseRNAi RNA interferenceRNAP RNA polymeraseRNP ribonucleoproteinROS reactive oxygen speciesRPE ribulose-5-phosphate epimeraseRPI ribose-5-phosphate isomeraseRRM RNA-recognition motifSAM S-adenosylmethionineSAPLIP saposin-like proteinSDR short-chain dehydrogenase/reductaseSERCA sarcoplasmic/endoplasmic reticulum

Ca2+-ATPaseSG stress granuleSHMT serine hydroxymethyltransferaseSHP Src homology region 2 domain-containing

protein tyrosine phosphataseSL spliced leader

Abbreviations © 2011 Biochemical Society

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SMUG small mucin geneSNARE soluble N-ethylmaleimide-sensitive

factor-attachment protein receptorSOCE store-operated Ca2+ entrySOD superoxide dismutaseStim stromal interaction moleculeTAL transaldolaseTAR transformation-associated recombinationTbPUF Trypanosoma brucei PUFTbZFP Trypanosoma brucei zinc-finger proteinTcPABP Trypanosoma cruzi PABPTcPUF Trypanosoma cruzi PUFTcUBP Trypanosoma cruzi U-rich RBPTic translocon of the inner chloroplast

membraneTKT transketolaseTNF tumour necrosis factorToc translocon of the outer chloroplast

membraneTOR target of rapamycinTriTryp Trypanosoma cruzi, Trypanosoma brucei and

Leishmania majorTS thymidylate synthaseTUNEL terminal deoxynucleotidyltransferase-

mediated dUTP nick-end labellingTvBspA Trichomona vaginalis BspAURE3-BP upstream regulatory element 3-binding

proteinUSER untranslated sequence element for regulationUTR untranslated regionVEC vaginal epithelial cellVP verapamilVps vacuolar sorting protein(s)VSG variant surface glycoproteinVSP variant surface proteinWHO World Health OrganizationXRNA exoribonuclease A

© 2011 Biochemical Society Abbreviations