Apicoplast-localized lysophosphatidic acid precursor assembly is required for bulk phospholipid synthesis in toxoplasma gondii and relies on an algal/plant-like glycerol 3-phosphate acyltransferase

Most apicomplexan parasites possess a non-photosynthetic plastid (the apicoplast), which harbors enzymes for a number of metabolic pathways, including a prokaryotic type II fatty acid synthesis (FASII) pathway. In Toxoplasma gondii, the causative agent of toxoplasmosis, the FASII pathway is essential for parasite growth and infectivity. However, little is known about the fate of fatty acids synthesized by FASII. In this study, we have investigated the function of a plant-like glycerol 3-phosphate acyltransferase (TgATS1) that localizes to the T. gondii apicoplast. Knock-down of TgATS1 resulted in significantly reduced incorporation of FASII-synthesized fatty acids into phosphatidic acid and downstream phospholipids and a severe defect in intracellular parasite replication and survival. Lipidomic analysis demonstrated that lipid precursors are made in, and exported from, the apicoplast for de novo biosynthesis of bulk phospholipids. This study reveals that the apicoplast-located FASII and ATS1, which are primarily used to generate plastid galactolipids in plants and algae, instead generate bulk phospholipids for membrane biogenesis in T. gondii

Developing advanced models of biological membranes with hydrogenous and deuterated natural glycerophospholipid mixtures

Cellular membranes are complex systems that consist of hundreds of different lipid species. Their investigation often relies on simple bilayer models including few synthetic lipid species. Glycerophospholipids (GPLs) extracted from cells are a valuable resource to produce advanced models of biological membranes. Here, we present the optimisation of a method previously reported by our team for the extraction and purification of various GPL mixtures from Pichia pastoris. The implementation of an additional purification step by High Performance Liquid Chromatography-Evaporative Light Scattering Detector (HPLC-ELSD) enabled for a better separation of the GPL mixtures from the neutral lipid fraction that includes sterols, and also allowed for the GPLs to be purified according to their different polar headgroups. Pure GPL mixtures at significantly high yields were produced through this approach. For this study, we utilised phoshatidylcholine (PC), phosphatidylserine (PS) and phosphatidylglycerol (PG) mixtures. These exhibit a single composition of the polar head, i.e., PC, PS or PG, but contain several molecular species consisting of acyl chains of varying length and unsaturation, which were determined by Gas Chromatography (GC). The lipid mixtures were produced both in their hydrogenous (H) and deuterated (D) versions and were used to form lipid bilayers both on solid substrates and as vesicles in solution. The supported lipid bilayers were characterised by quartz crystal microbalance with dissipation monitoring (QCM-D) and neutron reflectometry (NR), whereas the vesicles by small angle X-ray (SAXS) and neutron scattering (SANS). Our results show that despite differences in the acyl chain composition, the hydrogenous and deuterated extracts produced bilayers with very comparable structures, which makes them valuable to design experiments involving selective deuteration with techniques such as NMR, neutron scattering or infrared spectroscopy.We are grateful to the ILL and the ESRF for awarding beamtimes (DOI: 105291/ILL-DATA.EASY-975) and (DOI: https://doi.org/10.15151/ESRF-DC-1026409781) respectively. Lipids were produced in the L-Lab (www.ill.eu/L-Lab) facility within the PSCM initiative at the ILL from biomass prepared in the D-Lab. We are grateful to Hanna Wacklin-Knecht (ESS) for useful discussions. This project received funding from the European Union's Horizon 2020 research and innovation program under grant agreement N 654000 (SINE2020) and from the League of advanced European Neutron Sources (LENS). CB, YYB and the GEMELI Lipidomic platform were supported by Agence Nationale de la Recherche, France (Project ApicoLipiAdapt grant ANR-21-CE44-0010), the Fondation pour la Recherche Médicale (FRM EQU202103012700), Laboratoire d'Excellence Parafrap, France (grant ANR-11-LABX-0024), LIA-IRP CNRS Program (Apicolipid project), the Université Grenoble Alpes (IDEX ISP Apicolipid), Indo-French Collaborative Research Program Grant CEFIPRA (Project 6003-1), and Région Auvergne Rhone-Alpes for the lipidomics analyses platform (Grant IRICE Project GEMELI). A.M. acknowledges the financial support from MICINN under grant PID2021-129054NA-I00.Peer reviewe

Division and adaptation to host nutritional environment of apicomplexan parasites depend on apicoplast lipid metabolic plasticity and host organelles remodelling

International audienc

Division and adaptation to host nutritional environment of apicomplexan parasites depend on apicoplast lipid metabolic plasticity and host organelles remodelling

International audienc

Plastids with or without galactoglycerolipids.

International audienceIn structural, functional, and evolutionary terms, galactoglycerolipids are signature lipids of chloroplasts. Their presence in nongreen plastids has been demonstrated in angiosperms and diatoms. Thus, galactoglycerolipids are considered as a landmark of green and nongreen plastids, deriving from either a primary or secondary endosymbiosis. The discovery of a plastid in Plasmodium falciparum, the causative agent of malaria, fueled the search for galactoglycerolipids as possible targets for treatments. However, recent data have provided evidence that the Plasmodium plastid does not contain any galactoglycerolipids. In this opinion article, we discuss questions raised by the loss of galactoglycerolipids during evolution: how have galactoglycerolipids been lost? How does the Plasmodium plastid maintain four membranes without these lipids? What are the main constituents instead of galactoglycerolipids

Paludisme

En 1996, la découverte qu’un organite limité par plusieurs membranes à l’intérieur des cellules de Plasmodium et de Toxoplasma était un vestige de chloroplaste a bouleversé notre vision de ces parasites dans « l’arbre de la vie » et ouvert un champ d’investigation nouveau pour la recherche de traitements antiparasitaires, en particulier antipaludiques. Cette revue résume notre compréhension de l’évolution sophistiquée des parasites du groupe des Apicomplexes, et couvre sommairement une décennie de recherche et de développement de candidats médicaments visant à cibler le parasite au niveau de son organite végétal. Il semble, 15 ans après la découverte de l’apicoplaste et 10 ans après la publication du génome complet de Plasmodium falciparum, que nous soyons arrivés au bout d’une première phase de tests des antibiotiques et des herbicides disponibles. La phase hépatique constitue le seul stade du développement parasitaire pour lequel certaines fonctions de l’apicoplaste, telles que la biosynthèse des acides gras, semblent indispensables. Concernant la phase érythrocytaire, les résultats récents orientent les recherches sur les processus contrôlant la biogenèse de l’apicoplaste et sur une fonction biologique particulière portée par cet organite, la biosynthèse des isoprénoïdes, comme cibles prometteuses pour de futurs traitements

The therapeutic potential of metal-based antimalarial agents: implications for the mechanism of action.

International audienceDespite recent encouraging advances against the disease, malaria remains a major public health problem affecting almost half a billion people and killing almost a million per annum. Due to a short arsenal of efficient antimalarial agents and the frequent appearance of resistance to the drugs in current use, which consequently reduce our means to treat patients, there is a very urgent and continuous need to develop new compounds. This perspective outlines a unique strategy for that purpose through the development of metal-based antimalarial agents. The examples presented here illustrate an attractive alternative to classical drugs

The apicoplast: a key target to cure malaria.

International audienceMalaria is one of the major global health problems. About 500 million humans are infected each year, and 1 million, mostly African children, die from malaria annually. No vaccine is yet in sight, and those drugs that have previously served us well are now losing ground against the disease as parasites become resistant to our best compounds. The need for development of new antimalarials is now more urgent than ever. An exciting avenue for development of new drugs emerged recently when it was discovered that the malaria parasites have a previously unrecognized evolutionary history aligned to plants. These parasites contain a subcellular compartment - the apicoplast - which is homologous to the chloroplast of plants and algae, in which photosynthesis occurs. The malaria chloroplast (apicoplast) has lost photosynthesis but it retains many chloroplast pathways, which are otherwise unique to plants. These pathways obviously do not exist in the human host and there has been considerable excitement about using the apicoplast as a parasite-specific Achilles' Heel. We propose to review the current state of development of novel compounds directed against this emerging target of malaria parasites with emphasis on the chemistry

Toxoplasma metabolic flexibility in different growth conditions

Apicomplexan parasites have complex metabolic networks that coordinate acquisition of metabolites by de novo synthesis and by scavenging from the host. Toxoplasma gondii has a wide host range and may rely on the flexibility of this metabolic network. Currently, the literature categorizes genes as essential or dispensable according to their dispensability for parasite survival under nutrient-replete in vitro conditions. However, recent studies revealed correlations between medium composition and gene essentiality. Therefore, nutrient availability in the host environment likely determines the requirement of metabolic pathways, which may redefine priorities for drug target identification in a clinical setting. Here we review the recent work characterizing some of the major Toxoplasma metabolic pathways and their functional adaptation to host nutrient content