Imperial College London

Professor Jake Baum

Faculty of Natural SciencesDepartment of Life Sciences

Professor of Cell Biology and Infectious Diseases
 
 
 
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Contact

 

+44 (0)20 7594 5420jake.baum Website

 
 
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Location

 

609Sir Alexander Fleming BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

122 results found

Witmer K, Dahalan F, Delves M, Yahiya S, Watson O, Straschil U, Chiwcharoen D, Sorboon B, Pukrittayakamee S, Pearson R, Howick V, Lawniczak M, White N, Dondorp A, Okell L, Chotivanich K, Ruecker A, Baum Jet al., 2020, Transmission of artemisinin-resistant malaria parasites to mosquitoes under antimalarial drug pressure, Antimicrobial Agents and Chemotherapy, ISSN: 0066-4804

Resistance to artemisinin-based combination therapy (ACT) in the Plasmodium falciparum parasite is threatening to reverse recent gains in reducing global deaths from malaria. Whilst resistance manifests as delayed parasite clearance in patients the phenotype can only spread geographically via the sexual stages and mosquito transmission. In addition to their asexual killing properties, artemisinin and its derivatives sterilise sexual male gametocytes. Whether resistant parasites overcome this sterilising effect has not, however, been fully tested. Here, we analysed P. falciparum clinical isolates from the Greater Mekong Subregion, each demonstrating delayed clinical clearance and known resistance-associated polymorphisms in Kelch13 (PfK13var). As well as demonstrating reduced asexual sensitivity to drug, certain PfK13var isolates demonstrated a marked reduction in sensitivity to artemisinin in an in vitro male gamete formation assay. Importantly, this same reduction in sensitivity was observed when the most resistant isolate was tested directly in mosquito feeds. These results indicate that, under artemisinin drug pressure, whilst sensitive parasites are blocked, resistant parasites continue transmission. This selective advantage for resistance transmission could favour acquisition of additional host-specificity or polymorphisms affecting partner drug sensitivity in mixed infections. Favoured resistance transmission under ACT coverage could have profound implications for the spread of multidrug resistant malaria beyond Southeast Asia.

Journal article

Blake T, Haase S, Baum J, 2020, Actomyosin forces and the energetics of red blood cell invasion by the malaria parasite Plasmodium falciparum, PLoS Pathogens, Vol: 16, ISSN: 1553-7366

All symptoms of malaria disease are associated with the asexual blood stages of development, involving cycles of red blood cell (RBC) invasion and egress by the Plasmodium spp. merozoite. Merozoite invasion is rapid and is actively powered by a parasite actomyosin motor. The current accepted model for actomyosin force generation envisages arrays of parasite myosins, pushing against short actin filaments connected to the external milieu that drive the merozoite forwards into the RBC. In Plasmodium falciparum, the most virulent human malaria species, Myosin A (PfMyoA) is critical for parasite replication. However, the precise function of PfMyoA in invasion, its regulation, the role of other myosins and overall energetics of invasion remain unclear. Here, we developed a conditional mutagenesis strategy combined with live video microscopy to probe PfMyoA function and that of the auxiliary motor PfMyoB in invasion. By imaging conditional mutants with increasing defects in force production, based on disruption to a key PfMyoA phospho-regulation site, the absence of the PfMyoA essential light chain, or complete motor absence, we define three distinct stages of incomplete RBC invasion. These three defects reveal three energetic barriers to successful entry: RBC deformation (pre-entry), mid-invasion initiation, and completion of internalisation, each requiring an active parasite motor. In defining distinct energetic barriers to invasion, these data illuminate the mechanical challenges faced in this remarkable process of protozoan parasitism, highlighting distinct myosin functions and identifying potential targets for preventing malaria pathogenesis.

Journal article

Eagon S, Hammill JT, Sigal M, Ahn KJ, Tryhorn JE, Koch G, Belanger B, Chaplan CA, Loop L, Kashtanova AS, Yniguez K, Lazaro H, Wilkinson SP, Rice AL, Falade MO, Takahashi R, Kim K, Cheung A, DiBernardo C, Kimball JJ, Winzeler EA, Eribez K, Mittal N, Gamo F-J, Crespo B, Churchyard A, Garcia-Barbazan I, Baum J, Anderson MO, Laleu B, Guy RKet al., 2020, Synthesis and Structure-Activity Relationship of Dual-Stage Antimalarial Pyrazolo[3,4-b]pyridines, JOURNAL OF MEDICINAL CHEMISTRY, Vol: 63, Pages: 11902-11919, ISSN: 0022-2623

Journal article

Moussaoui D, Robblee JP, Auguin D, Krementsova EB, Haase S, Blake TCA, Baum J, Robert-Paganin J, Trybus KM, Houdusse Aet al., 2020, Full-length Plasmodium falciparum myosin A and essential light chain PfELC structures provide new anti-malarial targets, ELIFE, Vol: 9, ISSN: 2050-084X

Journal article

Ashdown G, Gaboriau D, Baum J, 2020, A machine learning approach to define antimalarial drug action from heterogeneous cell-based screens, Science Advances, Vol: 6, ISSN: 2375-2548

Drug resistance threatens the effective prevention and treatment of an ever-increasing range ofhuman infections. This highlights an urgent need for new and improved drugs with novelmechanisms of action to avoid cross-resistance. Current cell-based drug screens are,however, restricted to binary live/dead readouts with no provision for mechanism of actionprediction. Machine learning methods are increasingly being used to improve informationextraction from imaging data. Such methods, however, work poorly with heterogeneouscellular phenotypes and generally require time-consuming human-led training. We havedeveloped a semi-supervised machine learning approach, combining human- and machinelabelled training data from mixed human malaria parasite cultures. Designed for highthroughput and high-resolution screening, our semi-supervised approach is robust to naturalparasite morphological heterogeneity and correctly orders parasite developmental stages. Ourapproach also reproducibly detects and clusters drug-induced morphological outliers bymechanism of action, demonstrating the potential power of machine learning for acceleratingcell-based drug discovery.

Journal article

Varghese S, Rahmani R, Drew DR, Beeson JG, Baum J, Smith BJ, Baell Jet al., 2020, Structure activity studies of truncated latrunculin analogues with anti-malarial activity, ChemMedChem, ISSN: 0014-827X

Malarial parasites employ actin dynamics for motility, and any disruption to these dynamics renders the parasites unable to effectively establish infection. Therefore, actin presents a potential target for malarial drug discovery, and naturally occurring actin inhibitors such as latrunculins are a promising starting point. However, the limited availability of the natural product and the laborious route for synthesis of latrunculins have hindered their potential development as drug candidates. In this regard, we recently described novel truncated latrunculins, with superior actin binding potency and selectivity towards P. falciparum actin than the canonical latrunculin B. In this paper, we further explore the truncated latrunculin core to summarize the SAR for inhibition of malaria motility. This study helps further understand the binding pattern of these analogues in order to develop them as drug candidates for malaria.

Journal article

Wang X, Wilkinson MD, Lin X, Ren R, Willison KR, Ivanov AP, Baum J, Edel JBet al., 2020, Correction: Single-molecule nanopore sensing of actin dynamics and drug binding, Chemical Science, Vol: 11, Pages: 8036-8038, ISSN: 2041-6520

Correction for ‘Single-molecule nanopore sensing of actin dynamics and drug binding’ by Xiaoyi Wang et al., Chem. Sci., 2020, 11, 970–979, DOI: 10.1039/C9SC05710B.

Journal article

Baum J, Pasvol G, Carter R, 2020, From 1950s malaria to COVID-19, NATURE, Vol: 582, Pages: 488-488, ISSN: 0028-0836

Journal article

Saunders CN, Cota E, Baum J, Tate EWet al., 2020, Peptide probes for Plasmodium falciparum MyoA tail interacting protein (MTIP): exploring the druggability of the malaria parasite motor complex, ACS Chemical Biology, Vol: 15, Pages: 1313-1320, ISSN: 1554-8929

Malaria remains an endemic tropical disease, and the emergence of Plasmodium falciparum parasites resistant to current front-line medicines means that new therapeutic targets are required. The Plasmodium glideosome is a multiprotein complex thought to be essential for efficient host red blood cell invasion. At its core is a myosin motor, Myosin A (MyoA), which provides most of the force required for parasite invasion. Here, we report the design and development of improved peptide-based probes for the anchor point of MyoA, the P. falciparum MyoA tail interacting protein (PfMTIP). These probes combine low nanomolar binding affinity with significantly enhanced cell penetration and demonstrable competitive target engagement with native PfMTIP through a combination of Western blot and chemical proteomics. These results provide new insights into the potential druggability of the MTIP/MyoA interaction and a basis for the future design of inhibitors.

Journal article

Llora-Batlle O, Michel-Todo L, Witmer K, Toda H, Fernandez-Becerra C, Baum J, Cortes Aet al., 2020, Conditional expression of PfAP2-G for controlled massive sexual conversion in Plasmodium falciparum, SCIENCE ADVANCES, Vol: 6, ISSN: 2375-2548

Journal article

Wilkinson MD, Lai H-E, Freemont PS, Baum Jet al., 2020, A biosynthetic platform for antimalarial drug discovery, Antimicrobial Agents and Chemotherapy, Vol: 64, Pages: 1-9, ISSN: 0066-4804

Advances in synthetic biology have enabled production of a variety of compounds using bacteria as a vehicle for complex compound biosynthesis. Violacein, a naturally occurring indole pigment with antibiotic properties, can be biosynthetically engineered in Escherichia coli expressing its non-native synthesis pathway. To explore whether this synthetic biosynthesis platform could be used for drug discovery, here we have screened bacterially-derived violacein against the main causative agent of human malaria, Plasmodium falciparum. We show the antiparasitic activity of bacterially-derived violacein against the P. falciparum 3D7 laboratory reference strain as well as drug-sensitive and resistant patient isolates, confirming the potential utility of this drug as an antimalarial. We then screen a biosynthetic series of violacein derivatives against P. falciparum growth. The demonstrated varied activity of each derivative against asexual parasite growth points to potential for further development of violacein as an antimalarial. Towards defining its mode of action, we show that biosynthetic violacein affects the parasite actin cytoskeleton, resulting in an accumulation of actin signal that is independent of actin polymerization. This activity points to a target that modulates actin behaviour in the cell either in terms of its regulation or its folding. More broadly, our data show that bacterial synthetic biosynthesis could become a suitable platform for antimalarial drug discovery with potential applications in future high-throughput drug screening with otherwise chemically-intractable natural products.

Journal article

Rueda-Zubiaurre A, Yahiya S, Fischer O, Hu X, Saunders C, Sharma S, Straschil U, Shen J, Tate EW, Delves M, Baum J, Barnard A, Fuchter MJet al., 2020, Structure-activity relationship studies of a novel class of transmission blocking antimalarials targeting male gametes., Journal of Medicinal Chemistry, Vol: 63, Pages: 2240-2262, ISSN: 0022-2623

Malaria is still a leading cause of mortality among children in the developing world, and despite the immense progress made in reducing the global burden, further efforts are needed if eradication is to be achieved. In this context, targeting transmission is widely recognized as a necessary intervention towards that goal. After carrying out a screen to discover new transmission-blocking agents, herein we report our medicinal chemistry efforts to study the potential of the most robust hit, DDD01035881, as a male-gamete targeted compound. We reveal key structural features for the activity of this series and identify analogues with greater potency and improved metabolic stability. We believe this study lays the groundwork for further development of this series as a transmission blocking agent.

Journal article

Witmer K, Dahalan FA, Delves MJ, Yahiya S, Watson OJ, Straschil U, Chiwcharoen D, Sornboon B, Pukrittayakamee S, Pearson RD, Howick VM, Lawniczak MKN, White NJ, Dondorp AM, Okell LC, Ruecker A, Chotivanich K, Baum Jet al., 2020, Artemisinin-resistant malaria parasites show enhanced transmission to mosquitoes under drug pressure

<jats:title>ABSTRACT</jats:title><jats:p>Resistance to artemisinin combination therapy (ACT) in the <jats:italic>Plasmodium falciparum</jats:italic> parasite is threatening to reverse recent gains in reducing global deaths from malaria. Whilst resistance manifests as delayed asexual parasite clearance in patients following ACT treatment, the phenotype can only spread geographically via the sexual cycle and subsequent transmission through the mosquito. Artemisinin and its derivatives (such as dihydroartemisinin, DHA) as well as killing the asexual parasite form are known to sterilize male, sexual-stage gametes from activation. Whether resistant parasites overcome this artemisinin-dependent sterilizing effect has not, however, been fully tested. Here, we analysed five <jats:italic>P. falciparum</jats:italic> clinical isolates from the Greater Mekong Subregion, each of which demonstrated delayed clinical clearance and carried known resistance-associated polymorphisms in the <jats:italic>Kelch13</jats:italic> gene (PfK13<jats:sup>var</jats:sup>). As well as demonstrating reduced sensitivity to artemisinin-derivates in <jats:italic>in vitro</jats:italic> asexual growth assays, certain PfK13<jats:sup>var</jats:sup> isolates also demonstrated a marked reduction in sensitivity to these drugs in an <jats:italic>in vitro</jats:italic> male gamete activation assay compared to a sensitive control. Importantly, the same reduction in sensitivity to DHA was observed when the most resistant isolate was assayed by standard membrane feeding assays using <jats:italic>Anopheles stephensi</jats:italic> mosquitoes. These results indicate that ACT use can favour resistant over sensitive parasite transmission. A selective advantage for resistant parasite transmission could also favour acquisition of further polymorphisms, such as mosquito host-specificity or antimalarial partne

Journal article

Wang X, Wilkinson MD, Lin X, Ren R, Willison KR, Ivanov A, Baum J, Edel Jet al., 2020, Single-molecule nanopore sensing of actin dynamics and drug binding, Chemical Science, Vol: 11, Pages: 970-979, ISSN: 2041-6520

Actin is a key protein in the dynamic processes within the eukaryotic cell. To date, methods exploring the molecular state of actin are limited to insights gained from structural approaches, providing a snapshot of protein folding, or methods that require chemical modifications compromising actin monomer thermostability. Nanopore sensing permits label-free investigation of native proteins and is ideally suited to study proteins such as actin that require specialised buffers and cofactors. Using nanopores, we determined the state of actin at the macromolecular level (filamentous or globular) and in its monomeric form bound to inhibitors. We revealed urea-dependent and voltage-dependent transitional states and observed unfolding process within which sub-populations of transient actin oligomers are visible. We detected, in real-time, filament-growth, and drug-binding at the single-molecule level demonstrating the promise of nanopores sensing for in-depth understanding of protein folding landscapes and for drug discovery.

Journal article

Warszawski S, Dekel E, Campeotto J, Marshall J, Wright K, Lyth O, Knop N, Regev-Rudzki N, Baum J, Draper S, Higgins M, Fleishman Set al., 2020, Design of a basigin-mimicking inhibitor targeting the malaria invasion protein RH5, Proteins: Structure, Function, and Bioinformatics, Vol: 88, Pages: 187-195, ISSN: 0887-3585

Many human pathogens use host cell-surface receptors to attach and invade cells. Often, thehost-pathogen interaction affinity is low, presenting opportunities to block invasion using asoluble, high-affinity mimic of the host protein. The Plasmodium falciparum reticulocyte-bindingprotein homolog 5 (RH5) provides an exciting candidate for mimicry: it is highly conserved andits moderate affinity binding to the human receptor basigin (KD≥1 μM) is an essential step inerythrocyte invasion by this malaria parasite. We used deep mutational scanning of a solublefragment of human basigin to systematically characterize point mutations that enhance basiginaffinity for RH5 and then used Rosetta to design a variant within the sequence space ofaffinity-enhancing mutations. The resulting seven-mutation design exhibited 2,500-fold higheraffinity (KD<1 nM) for RH5 with a very slow binding off rate (0.23 h-1) and reduced the effectivePlasmodium growth-inhibitory concentration by at least tenfold compared to human basigin. Thedesign provides a favorable starting point for engineering on-rate improvements that are likelyto be essential to reach therapeutically effective growth inhibition. Designed mimics may providetherapeutic advantages over antibodies, since the mimics bind to essential surfaces on the targetpathogen proteins, reducing the likelihood for the emergence of escape mutants

Journal article

Ashdown GW, Dimon M, Fan M, Terán FS-R, Witmer K, Gaboriau DCA, Armstrong Z, Hazard J, Ando DM, Baum Jet al., 2019, A machine learning approach to define antimalarial drug action from heterogeneous cell-based screens, Publisher: Cold Spring Harbor Laboratory

<jats:title>Abstract</jats:title><jats:p>Drug resistance threatens the effective prevention and treatment of an ever-increasing range of human infections. This highlights an urgent need for new and improved drugs with novel mechanisms of action to avoid cross-resistance. Current cell-based drug screens are, however, restricted to binary live/dead readouts with no provision for mechanism of action prediction. Machine learning methods are increasingly being used to improve information extraction from imaging data. Such methods, however, work poorly with heterogeneous cellular phenotypes and generally require time-consuming human-led training. We have developed a semi-supervised machine learning approach, combining human- and machine-labelled training data from mixed human malaria parasite cultures. Designed for high-throughput and high-resolution screening, our semi-supervised approach is robust to natural parasite morphological heterogeneity and correctly orders parasite developmental stages. Our approach also reproducibly detects and clusters drug-induced morphological outliers by mechanism of action, demonstrating the potential power of machine learning for accelerating cell-based drug discovery.</jats:p><jats:sec><jats:title>One Sentence Summary</jats:title><jats:p>A machine learning approach to classifying normal and aberrant cell morphology from plate-based imaging of mixed malaria parasite cultures, facilitating clustering of drugs by mechanism of action.</jats:p></jats:sec>

Working paper

Del Rosario M, Periz J, Pavlou G, Lyth O, Latorre-Barragan F, Das S, Pall GS, Stortz JF, Lemgruber L, Whitelaw JA, Baum J, Tardieux I, Meissner Met al., 2019, Apicomplexan F-actin is required for efficient nuclear entry during host cell invasion, EMBO REPORTS, Vol: 20, ISSN: 1469-221X

Journal article

Malpartida-Cardenas K, Miscourides N, Rodriguez-Manzano J, Yu L-S, Moser N, Baum J, Georgiou Pet al., 2019, Quantitative and rapid Plasmodium falciparum malaria diagnosis and artemisinin-resistance detection using a CMOS Lab-on-Chip platform, Biosensors and Bioelectronics, Vol: 145, ISSN: 0956-5663

Early and accurate diagnosis of malaria and drug-resistance is essential to effective disease management. Available rapid malaria diagnostic tests present limitations in analytical sensitivity, drug-resistance testing and/or quantification. Conversely, diagnostic methods based on nucleic acid amplification stepped forwards owing to their high sensitivity, specificity and robustness. Nevertheless, these methods commonly rely on optical measurements and complex instrumentation which limit their applicability in resource-poor, point-of-care settings. This paper reports the specific, quantitative and fully-electronic detection of Plasmodium falciparum, the predominant malaria-causing parasite worldwide, using a Lab-on-Chip platform developed in-house. Furthermore, we demonstrate on-chip detection of C580Y, the most prevalent single-nucleotide polymorphism associated to artemisinin-resistant malaria. Real-time non-optical DNA sensing is facilitated using Ion-Sensitive Field-Effect Transistors, fabricated in unmodified complementary metal-oxide-semiconductor (CMOS) technology, coupled with loop-mediated isothermal amplification. This work holds significant potential for the development of a fully portable and quantitative malaria diagnostic that can be used as a rapid point-of-care test.

Journal article

Eden Primary C, Straschil U, Witmer K, Delves M, Marks S, Baum Jet al., 2019, Screen of traditional soup broths with reported antipyretic activity towards the discovery of potential antimalarials, Archives of Disease in Childhood, Vol: 104, Pages: 1138-1142, ISSN: 0003-9888

Objective The global impact of artemisinin-based combination therapies on malaria-associated mortality and their origins in ancient Chinese medicine has heightened interest in the natural discovery of future antimalarials.Methods A double-blind study to identify potential ingredients with antimalarial activity from traditional remedies with reported antipyretic properties. Recipes of clear broths, passed down by tradition in families of diverse ethnic origin, were sourced by school children. Broths were then tested for their ability to arrest malaria parasite asexual growth or sexual stage development in vitro. Clear broth extract was incubated with in vitro cultures of Plasmodium falciparum asexual or mature sexual stage cultures and assayed for parasite viability after 72 hours.Results Of the 56 broths tested, 5 were found to give >50% in vitro growth inhibition against P. falciparum asexual blood stages, with 2 having comparable inhibition to that seen with dihydroartemisinin, a leading antimalarial. Four other broths were found to have >50% transmission blocking activity, preventing male parasite sexual stage development. After unblinding, two active broths were found to be from siblings from different classes, who had brought in the same vegetarian soup, demonstrating assay robustness.Conclusions This screening approach succeeded in finding broths with activity against malaria parasite in vitro growth, arising from complex vegetable and/or meat-based broths. This represented a successful child education exercise, in teaching about the interface between natural remedies, traditional medicine and evidence-based drug discovery.

Journal article

Koch M, Cegla J, Jones B, Lu Y, Mallar Z, Blagborough A, Angrisano F, Baum Jet al., 2019, The effects of dyslipidaemia and cholesterol modulation on erythrocyte susceptibility to malaria parasite infection, Malaria Journal, Vol: 18, ISSN: 1475-2875

BackgroundMalaria disease commences when blood-stage parasites, called merozoites, invade human erythrocytes. Whilst the process of invasion is traditionally seen as being entirely merozoite-driven, emerging data suggests erythrocyte biophysical properties markedly influence invasion. Cholesterol is a major determinant of cell membrane biophysical properties demanding its interrogation as a potential mediator of resistance to merozoite invasion of the erythrocyte. MethodsBiophysical measurements of erythrocyte deformability by flicker spectroscopy were used to assess changes in erythrocyte bending modulus on forced integration of cholesterol and how these artificial changes affect invasion by human Plasmodium falciparum merozoites. To validate these observations in a natural context, either murine Plasmodium berghei or human Plasmodium falciparum merozoites were tested for their ability to invade erythrocytes from a hypercholesterolaemic mouse model or human clinical erythrocyte samples deriving from patients with a range of serum cholesterol concentrations, respectively. ResultsErythrocyte bending modulus (a measure of deformability) was shown to be markedly affected by artificial modulation of cholesterol content and negatively correlated with merozoite invasion efficiency. In an in vitro infection context, however, erythrocytes taken from hypercholesterolaemic mice or from human clinical samples with varying serum cholesterol levels showed little difference in their susceptibility to merozoite invasion. Explaining this, membrane cholesterol levels in both mouse and human hypercholesterolaemia erythrocytes were subsequently found to be no different from matched normal serum controls.ConclusionsBased on these observations, serum cholesterol does not appear to impact on erythrocyte susceptibility to merozoite entry. Indeed, no relationship between serum cholesterol and cholesterol content of the erythrocyte is apparent. This work, nonetheless, suggests that native p

Journal article

Wang X, Wilkinson MD, Lin X, Ren R, Willison K, Ivanov AP, Baum J, Edel JBet al., 2019, Single-molecule nanopore sensing of actin dynamics and drug binding, Publisher: Cold Spring Harbor Laboratory

<jats:title>Abstract</jats:title><jats:p>Actin is a key protein in the dynamic processes within the eukaryotic cell. To date, methods exploring the molecular state of actin are limited to insights gained from structural approaches, providing a snapshot of protein folding, or methods that require chemical modifications compromising actin monomer thermostability. Nanopore sensing permits label-free investigation of native proteins and is ideally suited to study proteins such as actin that require specialised buffers and cofactors. Using nanopores we determined the state of actin at the macromolecular level (filamentous or globular) and in its monomeric form bound to inhibitors. We revealed urea-dependent and voltage-dependent transitional states and observed unfolding process within which sub-populations of transient actin oligomers are visible. We detected, in real-time, drug-binding and filament-growth events at the single-molecule level. This enabled us to calculate binding stoichiometries and to propose a model for protein dynamics using unmodified, native actin molecules, demostrating the promise of nanopores sensing for in-depth understanding of protein folding landscapes and for drug discovery.</jats:p>

Working paper

Wilkinson M, Lai H-E, Freemont P, Baum Jet al., 2019, A biosynthetic platform for antimalarial drug discovery, Publisher: bioRxiv

ABSTRACT Advances in synthetic biology have enabled production of a variety of compounds using bacteria as a vehicle for complex compound biosynthesis. Violacein, a naturally occurring indole pigment with antibiotic properties, can be biosynthetically engineered in Escherichia coli expressing its non-native synthesis pathway. To explore whether this synthetic biosynthesis platform could be used for drug discovery, here we have screened bacterially-derived violacein against the main causative agent of human malaria, Plasmodium falciparum . We show the antiparasitic activity of bacterially-derived violacein against the P. falciparum 3D7 laboratory reference strain as well as drug-sensitive and resistant patient isolates, confirming the potential utility of this drug as an antimalarial. We then screen a biosynthetic series of violacein derivatives against P. falciparum growth. The demonstrated varied activity of each derivative against asexual parasite growth points to potential for further development of violacein as an antimalarial. Towards defining its mode of action, we show that biosynthetic violacein affects the parasite actin cytoskeleton, resulting in an accumulation of actin signal that is independent of actin polymerization. This activity points to a target that modulates actin behaviour in the cell either in terms of its regulation or its folding. More broadly, our data show that bacterial synthetic biosynthesis is a suitable platform for antimalarial drug discovery with potential applications in high-throughput and cost-effective drug screening with otherwise chemically-intractable natural products.

Working paper

Satchwell TJ, Wright KE, Haydn-Smith KL, Sanchez-Roman Teran F, Moura PL, Hawksworth J, Frayne J, Toye AM, Baum Jet al., 2019, Genetic manipulation of cell line derived reticulocytes enables dissection of host malaria invasion requirements, NATURE COMMUNICATIONS, Vol: 10, ISSN: 2041-1723

Journal article

Baum J, Robert-Paginin J, Robblee J, Auguin D, Blake T, Bookwalter C, Krementsova E, Moussaoui D, Previs M, Jousset G, Trybus K, Houdusse Aet al., 2019, Plasmodium myosin a drives parasite invasion by an atypical force generating mechanism, Nature Communications, Vol: 10, ISSN: 2041-1723

Plasmodium parasites are obligate intracellular protozoa and causative agents of malaria, responsible for half a million deaths each year. The lifecycle progression of the parasite is reliant on cell motility, a process driven by Myosin A, an unconventional single-headed class XIV molecular motor. Here we demonstrate that myosin A from Plasmodium falciparum (PfMyoA) is critical for red blood cell invasion. Further, using a combination of X-ray crystallography, kinetics, and in vitro motility assays, we elucidate the non-canonical interactions that drive this motor’s function. We show that PfMyoA motor properties are tuned by heavy chain phosphorylation (Ser19), with unphosphorylated PfMyoA exhibiting enhanced ensemble force generation at the expense of speed. Regulated phosphorylation may therefore optimize PfMyoA for enhanced force generation during parasite invasion or for fast motility during dissemination. The three PfMyoA crystallographic structures presented here provide a blueprint for discovery of specific inhibitors designed to prevent parasite infection.

Journal article

Satchwell TJ, Wright K, Haydn-Smith K, Sanchez-Roman Teran F, Moura P, Hawksworth J, Frayne J, Toye A, Baum Jet al., 2019, Stable knockout and complementation of receptor expression using in vitro cell line derived reticulocytes for dissection of host malaria invasion requirements, Nature Communications, ISSN: 2041-1723

Investigatingthe role host erythrocyteproteins play in malaria infection is hampered by the genetic intractability of this anucleate cell. Here we report that reticulocytes derived through in vitro differentiation of an enucleation-competent immortalized erythroblast cell line (BEL-A) support both successful invasion and intracellular development of the malaria parasite Plasmodium falciparum. Using CRISPR-mediated gene knockout and subsequent complementation, we validate an essential role for the erythrocyte receptor basigin in P. falciparum invasion and, for the first time, demonstrate rescueby receptor re-expression.Successful invasion of reticulocytes complemented with a truncated mutant excludes a functional role for the basigincytoplasmic domain during invasion. Contrastingly, knockout of cyclophilin B, reported to participate in invasion and interact with basigin, did not impactinvasive susceptibility of reticulocytes.These data establish the use of reticulocytes derived from immortalized erythroblasts as a powerful model system to explore hypotheses regarding host receptor requirements for P. falciparum invasion.

Journal article

Yahiya S, Rueda-Zubiaurre A, Delves MJ, Fuchter MJ, Baum Jet al., 2019, The antimalarial screening landscape-looking beyond the asexual blood stage, CURRENT OPINION IN CHEMICAL BIOLOGY, Vol: 50, Pages: 1-9, ISSN: 1367-5931

Journal article

Knuepfer E, Wright KE, Prajapati SK, Rawlinson TA, Mohring F, Koch M, Lyth OR, Howell SA, Villasis E, Snijders AP, Moon RW, Draper SJ, Rosanas-Urgell A, Higgins MK, Baum J, Holder AAet al., 2019, Divergent roles for the RH5 complex components, CyRPA and RIPR in human-infective malaria parasites, PLOS PATHOGENS, Vol: 15, ISSN: 1553-7366

Journal article

Malpartida-Cardenas K, Miscourides N, Rodriguez-Manzano J, Yu LS, Baum J, Georgiou Pet al., 2019, Quantitative and rapid Plasmodium falciparum malaria diagnosis and artemisinin-resistance detection using a CMOS Lab-on-Chip platform, Publisher: Cold Spring Harbor Laboratory

<jats:title>Abstract</jats:title><jats:p>Early and accurate diagnosis of malaria and drug-resistance is essential to effective disease management. Available rapid malaria diagnostic tests present limitations in analytical sensitivity, drug-resistant testing and/or quantification. Conversely, diagnostic methods based on nucleic acid amplification stepped forwards owing to their high sensitivity, specificity and robustness. Nevertheless, these methods commonly rely on optical measurements and complex instrumentation which limit their applicability in resource-poor, point-of-care settings. This paper reports the specific, quantitative and fully-electronic detection of <jats:italic>Plas-modium falciparum</jats:italic>, the predominant malaria-causing parasite worldwide, using a Lab-on-Chip platform developed in-house. Furthermore, we demonstrate on-chip detection of C580Y, the most prevalent single-nucleotide polymorphism associated to artemisinin-resistant malaria. Real-time non-optical DNA sensing is facilitated using Ion-Sensitive Field-Effect Transistors, fabricated in unmodified complementary metal-oxide-semiconductor technology, coupled with loop-mediated isothermal amplification. This work holds significant potential for the development of a fully portable and quantitative malaria diagnostic that can be used as a rapid point-of-care test.</jats:p>

Working paper

Baragaña B, Forte B, Choi R, Nakazawa Hewitt S, Bueren-Calabuig JA, Pisco JP, Peet C, Dranow DM, Robinson DA, Jansen C, Norcross NR, Vinayak S, Anderson M, Brooks CF, Cooper CA, Damerow S, Delves M, Dowers K, Duffy J, Edwards TE, Hallyburton I, Horst BG, Hulverson MA, Ferguson L, Jiménez-Díaz MB, Jumani RS, Lorimer DD, Love MS, Maher S, Matthews H, McNamara CW, Miller P, O'Neill S, Ojo KK, Osuna-Cabello M, Pinto E, Post J, Riley J, Rottmann M, Sanz LM, Scullion P, Sharma A, Shepherd SM, Shishikura Y, Simeons FRC, Stebbins EE, Stojanovski L, Straschil U, Tamaki FK, Tamjar J, Torrie LS, Vantaux A, Witkowski B, Wittlin S, Yogavel M, Zuccotto F, Angulo-Barturen I, Sinden R, Baum J, Gamo F-J, Mäser P, Kyle DE, Winzeler EA, Myler PJ, Wyatt PG, Floyd D, Matthews D, Sharma A, Striepen B, Huston CD, Gray DW, Fairlamb AH, Pisliakov AV, Walpole C, Read KD, Van Voorhis WC, Gilbert IHet al., 2019, Lysyl-tRNA synthetase as a drug target in malaria and cryptosporidiosis., Proc Natl Acad Sci U S A

Malaria and cryptosporidiosis, caused by apicomplexan parasites, remain major drivers of global child mortality. New drugs for the treatment of malaria and cryptosporidiosis, in particular, are of high priority; however, there are few chemically validated targets. The natural product cladosporin is active against blood- and liver-stage Plasmodium falciparum and Cryptosporidium parvum in cell-culture studies. Target deconvolution in P. falciparum has shown that cladosporin inhibits lysyl-tRNA synthetase (PfKRS1). Here, we report the identification of a series of selective inhibitors of apicomplexan KRSs. Following a biochemical screen, a small-molecule hit was identified and then optimized by using a structure-based approach, supported by structures of both PfKRS1 and C. parvum KRS (CpKRS). In vivo proof of concept was established in an SCID mouse model of malaria, after oral administration (ED90 = 1.5 mg/kg, once a day for 4 d). Furthermore, we successfully identified an opportunity for pathogen hopping based on the structural homology between PfKRS1 and CpKRS. This series of compounds inhibit CpKRS and C. parvum and Cryptosporidium hominis in culture, and our lead compound shows oral efficacy in two cryptosporidiosis mouse models. X-ray crystallography and molecular dynamics simulations have provided a model to rationalize the selectivity of our compounds for PfKRS1 and CpKRS vs. (human) HsKRS. Our work validates apicomplexan KRSs as promising targets for the development of drugs for malaria and cryptosporidiosis.

Journal article

Ashdown GW, Dimon M, Fan M, Teran FS, Witmer K, Gaboriau D, Hazard J, Ando MD, Baum Jet al., 2019, MACHINE LEARNING IDENTIFICATION OF MALARIA PARASITE CELL DEVELOPMENT AND ANTIMALARIAL DRIVEN PHENOTYPES USING HIGH-THROUGHPUT, HIGH-RESOLUTION FLUORESCENCE IMAGING, 68th Annual Meeting of the American-Society-for-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 129-129, ISSN: 0002-9637

Conference paper

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