Maternally supplied S-acyl-transferase is required for crystalloid organelle formation and transmission of the malaria parasite.
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ABSTRACT:
SUBMITTER: Santos JM
PROVIDER: S-EPMC4932936 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The post-translational addition of C-16 long chain fatty acids to protein cysteine residues is catalysed by palmitoyl-S-acyl-transferases (PAT) and affects the affinity of a modified protein for membranes and therefore its subcellular localisation. In apicomplexan parasites this reversible protein modification regulates numerous biological processes and specifically affects cell motility, and invasion of host cells by Plasmodium falciparum merozoites and Toxoplasma gondii tachyzoites. Using inhibitor studies we show here that palmitoylation is key to transformation of zygotes into ookinetes during initial mosquito infection with P. berghei. We identify DHHC2 as a unique PAT mediating ookinete formation and morphogenesis. Essential for life cycle progression in asexual blood stage parasites and thus refractory to gene deletion analyses, we used promoter swap (ps) methodology to maintain dhhc2 expression in asexual blood stages but down regulate expression in sexual stage parasites and during post-fertilization development of the zygote. The ps mutant showed normal gamete formation, fertilisation and DNA replication to tetraploid cells, but was characterised by a complete block in post-fertilisation development and ookinete formation. Our report highlights the crucial nature of the DHHC2 palmitoyl-S-acyltransferase for transmission of the malaria parasite to the mosquito vector through its essential role for ookinete morphogenesis.
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Project description:Host-derived factors are sucked into midgut of mosquitoes during natural malaria transmission, but their influence on malaria transmission is largely unknown. We reported that mouse complement C3 taken into mosquitoes significantly promoted malaria transmission either in laboratory or in field. This effect was attributed to the reduction of microbiota abundance in mosquito midgut by host-derived C3 through direct lyses the predominant symbiont bacteria Elizabethkingia anopheles. Elizabethkingia anopheles symbiont bacteria were demonstrated to be detrimental to malaria sexual stages in mosquitoes. Strikingly, the promoted effect of host C3 on malaria transmission was confirmed by laboratory mosquitoes membrane-feeding on Plasmodium falciparum. Therefore, we reveal a novel strategy of malaria parasite to utilize host complement C3 to promote its transmission, and the administration of C3 inhibitor would provide us a novel strategy to control malaria transmission.
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Project description:In high-transmission regions, we expect parasite lineages within complex malaria infections to be unrelated due to parasite inoculations from different mosquitoes. This project was designed to test this prediction. We generated 485 single-cell genome sequences from fifteen P. falciparum malaria patients from Chikhwawa, Malawi-an area of intense transmission. Patients harbored up to seventeen unique parasite lineages. Surprisingly, parasite lineages within infections tend to be closely related, suggesting that superinfection by repeated mosquito bites is rarer than co-transmission of parasites from a single mosquito. Both closely and distantly related parasites comprise an infection, suggesting sequential transmission of complex infections between multiple hosts. We identified tetrads and reconstructed parental haplotypes, which revealed the inbred ancestry of infections and non-Mendelian inheritance. Our analysis suggests strong barriers to secondary infection and outbreeding amongst malaria parasites from a high transmission setting, providing unexpected insights into the biology and transmission of malaria.
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Project description:Coendemicity between the human immunodeficiency virus (HIV) and Plasmodium parasites, the causative agents of acquired immunodeficiency syndrome (AIDS) and malaria, respectively, occurs in several regions around the world. Although the impact of the interaction between these two organisms is not well understood, it is thought that the outcome of either disease may be negatively influenced by coinfection. Therefore, it is important to understand how current first-line antiretroviral therapies (ART) might impact Plasmodium infection in these regions. Here, we describe the effect of 18 antiretroviral compounds and of first-line ART on the blood and sporogonic stages of Plasmodium berghei in vitro and in vivo. We show that the combination zidovudine + lamivudine + lopinavir/ritonavir (LPV/r), employed as first-line HIV treatment in the field, has a strong inhibitory activity on the sporogonic stages of P. berghei and that several non-nucleoside reverse transcriptase inhibitors (NNRTI) have a moderate effect on this stage of the parasite's life cycle. Our results expose the effect of current first-line ART on Plasmodium infection and identify potential alternative therapies for HIV/AIDS that might impact malaria transmission.
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Project description:During transmission of malaria-causing parasites from mosquitoes to mammals, Plasmodium sporozoites migrate rapidly in the skin to search for a blood vessel. The high migratory speed and narrow passages taken by the parasites suggest considerable strain on the sporozoites to maintain their shape. Here we show that the membrane-associated protein, concavin, is important for maintenance of the Plasmodium sporozoite shape inside salivary glands of mosquitoes and during migration in the skin. Concavin-GFP localizes at the cytoplasmic periphery and concavin(-) sporozoites progressively round up upon entry of salivary glands. Rounded concavin(-) sporozoites fail to pass through the narrow salivary ducts and are rarely ejected by mosquitoes, while normally shaped concavin(-) sporozoites are transmitted. Strikingly, motile concavin(-) sporozoites disintegrate while migrating through the skin leading to parasite arrest or death and decreased transmission efficiency. Collectively, we suggest that concavin contributes to cell shape maintenance by riveting the plasma membrane to the subtending inner membrane complex. Interfering with cell shape maintenance pathways might hence provide a new strategy to prevent a malaria infection.
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Project description:The malaria parasite replicates within an intraerythrocytic parasitophorous vacuole (PV). Eventually, in a tightly regulated process called egress, proteins of the PV and intracellular merozoite surface are modified by an essential parasite serine protease called PfSUB1, whilst the enclosing PV and erythrocyte membranes rupture, releasing merozoites to invade fresh erythrocytes. Inhibition of the Plasmodium falciparum cGMP-dependent protein kinase (PfPKG) prevents egress, but the underlying mechanism is unknown. Here we show that PfPKG activity is required for PfSUB1 discharge into the PV, as well as for release of distinct merozoite organelles called micronemes. Stimulation of PfPKG by inhibiting parasite phosphodiesterase activity induces premature PfSUB1 discharge and egress of developmentally immature, non-invasive parasites. Our findings identify the signalling pathway that regulates PfSUB1 function and egress, and raise the possibility of targeting PfPKG or parasite phosphodiesterases in therapeutic approaches to dysregulate critical protease-mediated steps in the parasite life cycle.
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Project description:During transmission of malaria-causing parasites from mosquitoes to mammals, Plasmodium sporozoites migrate rapidly in the skin to search for a blood vessel. The high migratory speed and narrow passages taken by the parasites suggest considerable strain on the sporozoites to maintain their shape. Here, we show that the membrane-associated protein, concavin, is important for the maintenance of the Plasmodium sporozoite shape inside salivary glands of mosquitoes and during migration in the skin. Concavin-GFP localizes at the cytoplasmic periphery and concavin(-) sporozoites progressively round up upon entry of salivary glands. Rounded concavin(-) sporozoites fail to pass through the narrow salivary ducts and are rarely ejected by mosquitoes, while normally shaped concavin(-) sporozoites are transmitted. Strikingly, motile concavin(-) sporozoites disintegrate while migrating through the skin leading to parasite arrest or death and decreased transmission efficiency. Collectively, we suggest that concavin contributes to cell shape maintenance by riveting the plasma membrane to the subtending inner membrane complex. Interfering with cell shape maintenance pathways might hence provide a new strategy to prevent a malaria infection.
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Project description:Kinesins are a superfamily of molecular motors that undertake ATP-dependent microtubule-based movement or regulate microtubule dynamics. Plasmodium species, which cause malaria and kill hundreds of thousands annually, encode ~9 kinesins in their genomes. Of these, two – kinesin-8B and kinesin-8X - are canonically classified as kinesin-8s, which in other eukaryotes typically modulate microtubule dynamics. Unexpectedly, Plasmodium kinesin-8B is required for development of the flagellated male gamete in the mosquito host, and its absence completely blocks parasite transmission. To understand the molecular basis of kinesin-8B’s essential role, we characterised the in vitro properties of the kinesin-8B motor domains from P. berghei and P. falciparum. Both motors drive plus-end directed ATP-dependent microtubule gliding, but also catalyse ATP-dependent microtubule depolymerisation. We determined the microtubule-bound structures of these motors using cryo-electron microscopy. P. berghei and P. falciparum kinesin-8B exhibit a very similar mode of microtubule interaction, in which Plasmodium-distinct sequences at the microtubule-kinesin interface influence motor function. Intriguingly, however, P. berghei kinesin-8B exhibits a non-canonical structural response to ATP analogue binding such that neck linker docking is not induced. Nevertheless, the neck linker region is absolutely required for motility and depolymerisation activities of these motors. Taken together, these data suggest that the mechanochemistry of Plasmodium kinesin-8Bs has been functionally tuned to efficiently contribute to flagella formation.
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