apicoplast

BACKGROUND: The phylum Apicomplexa includes intracellular parasites causing immense global disease burden, the deadliest of them being the human malaria parasite Plasmodium falciparum, which invades and replicates within erythrocytes. The cytoskeletal protein actin is well conserved within apicomplexans but divergent from mammalian actins, and was primarily reported to function during host cell invasion. However, novel invasion mechanisms have been described for several apicomplexans, and specific functions of the acto-myosin system are being reinvestigated...

Babesiosis is a globally important zoonotic disease caused by tick-borne intraerythrocytic protozoan of the genus Babesia (phylum apicomplexa). In China, there are five species that infect cattle buffalo and cause great economic loss, which include Babesia bigemina, B. bovis, B. major, B. ovata, and B. orientalis. Among them, B. orientalis is the most recently identified new Babesia species epidemic in China. This review summarized the work done in the past 33 years to give an overview of what learned about this parasite...

The malaria parasite P. falciparum exports a large number of proteins to its host cell, the mature human erythrocyte. Although the function of the majority of these proteins is not well understood, many exported proteins appear to play a role in modification of the erythrocyte following invasion. Protein export to the erythrocyte is a secretory process that begins with entry to the endoplasmic reticulum. For most exported proteins, this step is mediated by hydrophobic signal peptides found towards the N-terminal end of proteins...

The relict plastid (apicoplast) of the malaria parasite is the site for important biochemical pathways and is essential for parasite survival. The SUF pathway of [Fe-S] cluster assembly in the apicoplast of Plasmodium spp. is of interest due to its absence in the human host suggesting the possibility of anti-malarial intervention through apicoplast [Fe-S] biogenesis. We report biochemical characterization of components of the Plasmodium falciparum apicoplast SUF pathway after the first step of sulfur mobilization...

Malaria is a predominant infectious disease, with a global footprint, but especially severe in developing countries in the African subcontinent. In recent years, drug-resistant malaria has become an alarming factor, and hence the requirement of new and improved drugs is more crucial than ever before. One of the promising locations for antimalarial drug target is the apicoplast, as this organelle does not occur in humans. The apicoplast is associated with many unique and essential pathways in many Apicomplexan pathogens, including Plasmodium...

Apicomplexan parasites cause a variety of important infectious diseases, including malaria, toxoplasma encephalitis, and severe diarrhea due to Cryptosporidium Most apicomplexans depend on an organelle called the apicoplast which is derived from a red algal endosymbiont. The apicoplast is essential for the parasite as the compartment of fatty acid, heme, and isoprenoid biosynthesis. The majority of the approximate 500 apicoplast proteins are nucleus encoded and have to be imported across the four membranes that surround the apicoplast...

BACKGROUND: Lipoic acid is a cofactor for α-keto acid dehydrogenase system that is involved in the central energy metabolism. In the apicomplexan parasite, Plasmodium, lipoic acid protein ligase 1 (LplA1) and LplA2 catalyse the ligation of acquired lipoic acid to the dehydrogenase complexes in the mitochondrion. The enzymes LipB and LipA mediate lipoic acid synthesis and ligation to the enzymes in the apicoplast. These enzymes in the lipoic acid metabolism machinery have been shown to play important roles in the biology of Plasmodium parasites, but the relationship between the enzymes is not fully elucidated...

Gene network (GN) inference from temporal gene expression data is a crucial and challenging problem in systems biology. Expression data sets usually consist of dozens of temporal samples, while networks consist of thousands of genes, thus rendering many inference methods unfeasible in practice. To improve the scalability of GN inference methods, we propose a novel framework called GeNICE, based on probabilistic GNs; the main novelty is the introduction of a clustering procedure to group genes with related expression profiles and to provide an approximate solution with reduced computational complexity...

The combination of drug resistance, lack of an effective vaccine, and ongoing conflict and poverty means that malaria remains a major global health crisis. Understanding metabolic pathways at all parasite life stages is important in prioritising and targeting novel anti-parasitic compounds. The unusual heme synthesis pathway of the rodent malaria parasite, Plasmodium berghei, requires eight enzymes distributed across the mitochondrion, apicoplast and cytoplasm. Deletion of the ferrochelatase (FC) gene, the final enzyme in the pathway, confirms that heme synthesis is not essential in the red blood cell stages of the life cycle but is required to complete oocyst development in mosquitoes...

Malaria is a lethal disease causing mortality to over millions each year. Drug resistance in the malarial parasite encouraged to discover effective antimalarial drug targets and drugs. An objective of this current study is to identify drug targets for malarial parasite. Genes unique, non-homologous to humans and essential for parasite are identified using BLASTn by comparing genomes between parasite and host. Further open BLASTp was used to filter the targets specific to Plasmodium species and later were subjected to gene property analysis to identify 65 potential targets...

The obligate intracellular parasite Toxoplasma gondii possesses a repertoire of 11 myosins. Three class XIV motors participate in motility, invasion and egress, whereas the class XXII myosin F is implicated in organelle positioning and inheritance of the apicoplast. Here we provide evidence that TgUNC acts as a chaperone dedicated to the folding, assembly and function of all Toxoplasma myosins. The conditional ablation of TgUNC recapitulates the phenome of the known myosins and uncovers two functions in parasite basal complex constriction and synchronized division within the parasitophorous vacuole...

The secretory pathway in Plasmodium falciparum has evolved to transport proteins to the host cell membrane and to an endosymbiotic organelle, the apicoplast. The latter can occur via the ER or the ER-Golgi route. Here, we study these three routes using proteins Erythrocyte Membrane Protein-1 (PfEMP1), Acyl Carrier Protein (ACP) and glutathione peroxidase-like thioredoxin peroxidase (PfTPxGl) and inhibitors of vesicular transport. As expected, the G protein-dependent vesicular fusion inhibitor AlF4(-) and microtubule destabilizing drug vinblastine block the trafficking of PfEMP-1, a protein secreted to the host cell membrane...

Toxoplasma gondii is an obligate intracellular apicomplexan parasite which is able to infect almost all warm-blooded animals. There is no information about the prevalence and genetic characterization of T. gondii in badgers (Melogale moschata) in China. Here, a total of 367 badgers were captured from different cities in Jiangxi province, Southern China. Genomic DNA was extracted from brain tissues of each badgers, and 57 (15.45%) of them were positive for T. gondii by semi-nested PCR of the B1 gene. The positive DNA samples were typed at 11 genetic markers, including 10 nuclear loci (SAG1, 5'-SAG2 and 3'-SAG2, alternative SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1) and an apicoplast locus (Apico), with multilocus polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technology...

The metabolic pathways associated with the mitochondrion and the apicoplast in Plasmodium, 2 parasite organelles of prokaryotic origin, are considered as suitable drug targets. In the present study, we have identified functional role of a novel ovarian tumour unit (OTU) domain-containing cysteine protease of Plasmodium falciparum (PfOTU). A C-terminal regulatable fluorescent affinity tag on native protein was utilised for its localization and functional characterization. Detailed studies showed vesicular localization of PfOTU and its association with the apicoplast...

Patatin-like phospholipases are involved in numerous cellular functions, including lipid metabolism and membranes remodeling. The patatin-like catalytic domain, whose phospholipase activity relies on a serine-aspartate dyad and an anion binding box, is widely spread among prokaryotes and eukaryotes. We describe TgPL2, a novel patatin-like phospholipase domain-containing protein from the parasitic protist Toxoplasma gondii. TgPL2 is a large protein, in which the key motifs for enzymatic activity are conserved in the patatin-like domain...

The evolutionary relationship between plants and the malarial parasite Plasmodium falciparum is well established and underscored by the P. falciparum apicoplast, an essential chloroplast-like organelle. As a result of this relationship, studies have demonstrated that herbicides active against plants are also active against P. falciparum and thus could act as antimalarial drug leads. Here we show the converse is also true; many antimalarial compounds developed for human use are highly herbicidal. We found that human antimalarial drugs (e...

Cytokinins are plant hormones that are involved in regulation of cell proliferation, cell cycle progression, and cell and plastid development. Here, we show that the apicomplexan parasites Toxoplasma gondii and Plasmodium berghei, an opportunistic human pathogen and a rodent malaria agent, respectively, produce cytokinins via a biosynthetic pathway similar to that in plants. Cytokinins regulate the growth and cell cycle progression of T. gondii by mediating expression of the cyclin gene TgCYC4. A natural form of cytokinin, trans-zeatin (t-zeatin), upregulated expression of this cyclin, while a synthetic cytokinin, thidiazuron, downregulated its expression...

Toxoplasma gondii is among the most prevalent protozoan parasites, which infects a wide range of organisms, including one-third of the human population. Its rapid intracellular replication within a vacuole requires efficient synthesis of glycerophospholipids. Cytidine diphosphate-diacylglycerol (CDP-DAG) serves as a major precursor for phospholipid synthesis. Given the peculiarities of lipid biogenesis, understanding the mechanism and physiological importance of CDP-DAG synthesis is particularly relevant in T...

Background Discovery of apicoplast as a drug target offers a new direction in the development of novel anti-malarial compounds, especially against the drug-resistant strains. Drugs such as azithromycin were reported to block the apicoplast development that leads to unusual phenotypes affecting the parasite. This phenomenon suggeststhat identification of new apicoplast inhibitors will aid in the anti-malarial drug discovery. Therefore, in this study, we developed a computational model to predict apicoplast inhibitors by applying state-of-the-art machine learning techniques...

Malaria has been present since ancient time and remains a major global health problem in developing countries. Plasmodium falciparum belongs to the phylum Apicomplexan, largely contain disease-causing parasites and characterized by the presence of apicoplast. It is a very essential organelle of P. falciparum responsible for the synthesis of key molecules required for the growth of the parasite. Indispensable nature of apicoplast makes it a potential drug target. Calcium signaling is important in the establishment of malaria parasite inside the host...