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The New England Journal of Medicine Sep 2021
Topics: Africa, Eastern; Artemisinins; Humans; Plasmodium falciparum
PubMed: 34551233
DOI: 10.1056/NEJMe2110659 -
MBio Jun 2021Artemisinin and its semisynthetic derivatives (ART) are fast acting, potent antimalarials; however, their use in malaria treatment is frequently confounded by...
Artemisinin and its semisynthetic derivatives (ART) are fast acting, potent antimalarials; however, their use in malaria treatment is frequently confounded by recrudescences from bloodstream parasites that enter into and later reactivate from a dormant persister state. Here, we provide evidence that the mitochondria of dihydroartemisinin (DHA)-exposed persisters are dramatically altered and enlarged relative to the mitochondria of young, actively replicating ring forms. Restructured mitochondrial-nuclear associations and an altered metabolic state are consistent with stress from reactive oxygen species. New contacts between the mitochondria and nuclei may support communication pathways of mitochondrial retrograde signaling, resulting in transcriptional changes in the nucleus as a survival response. Further characterization of the organelle communication and metabolic dependencies of persisters may suggest strategies to combat recrudescences of malaria after treatment. The major first-line treatment for malaria, especially the deadliest form caused by Plasmodium falciparum, is combination therapy with an artemisinin-based drug (ART) plus a partner drug to assure complete cure. Without an effective partner drug, ART administration alone can fail because of the ability of small populations of blood-stage malaria parasites to enter into a dormant state and survive repeated treatments for a week or more. Understanding the nature of parasites in dormancy (persisters) and their ability to wake and reestablish actively propagating parasitemias (recrudesce) after ART exposure may suggest strategies to improve treatment outcomes and counter the threats posed by parasites that develop resistance to partner drugs. Here, we show that persisters have dramatically altered mitochondria and mitochondrial-nuclear interactions associated with features of metabolic quiescence. Restructured associations between the mitochondria and nuclei may support signaling pathways that enable the ART survival responses of dormancy.
Topics: Antimalarials; Artemisinins; Cell Nucleus; Erythrocytes; Humans; Malaria, Falciparum; Mitochondria; Plasmodium falciparum
PubMed: 34044591
DOI: 10.1128/mBio.00753-21 -
Trends in Biochemical Sciences Feb 2022The difficulty of faithfully recapitulating malarial protein complexes in heterologous expression systems has long impeded structural study for much of the Plasmodium... (Review)
Review
The difficulty of faithfully recapitulating malarial protein complexes in heterologous expression systems has long impeded structural study for much of the Plasmodium falciparum proteome. However, recent advances in single-particle cryo electron microscopy (cryoEM) now enable structure determination at atomic resolution with significantly reduced requirements for both sample quantity and purity. Combined with recent developments in gene editing, these advances open the door to structure determination and structural proteomics of macromolecular complexes enriched directly from P. falciparum parasites. Furthermore, the combination of cryoEM with the rapidly emerging use of in situ cryo electron tomography (cryoET) to directly visualize ultrastructures and protein complexes in the native cellular context will yield exciting new insights into the molecular machinery underpinning malaria parasite biology and pathogenesis.
Topics: Animals; Cryoelectron Microscopy; Malaria; Malaria, Falciparum; Parasites; Plasmodium falciparum
PubMed: 34887149
DOI: 10.1016/j.tibs.2021.10.006 -
Malaria Journal Dec 2019Malaria continues to be endemic in the coast and Amazon regions of Ecuador. Clarifying current Plasmodium falciparum resistance in the country will support malaria...
BACKGROUND
Malaria continues to be endemic in the coast and Amazon regions of Ecuador. Clarifying current Plasmodium falciparum resistance in the country will support malaria elimination efforts. In this study, Ecuadorian P. falciparum parasites were analysed to determine their drug resistance genotypes and phenotypes.
METHODS
Molecular analyses were performed to search for mutations in known resistance markers (Pfcrt, Pfdhfr, Pfdhps, Pfmdr1, k13). Pfmdr1 copy number was determined by qPCR. PFMDR1 transporter activity was characterized in live parasites using live cell imaging in combination with the Fluo-4 transport assay. Chloroquine, quinine, lumefantrine, mefloquine, dihydroartemisinin, and artemether sensitivities were measured by in vitro assays.
RESULTS
The majority of samples from this study presented the CVMNT genotype for Pfcrt (72-26), NEDF SDFD mutations in Pfmdr1 and wild type genotypes for Pfdhfr, Pfdhps and k13. The Ecuadorian P. falciparum strain ESM-2013 showed in vitro resistance to chloroquine, but sensitivity to quinine, lumefantrine, mefloquine, dihydroartemisinin and artemether. In addition, transport of the fluorochrome Fluo-4 from the cytosol into the digestive vacuole (DV) of the ESM-2013 strain was minimally detected in the DV. All analysed samples revealed one copy of Pfmdr1.
CONCLUSION
This study indicates that Ecuadorian parasites presented the genotype and phenotype for chloroquine resistance and were found to be sensitive to SP, artemether-lumefantrine, quinine, mefloquine, and dihydroartemisinin. The results suggest that the current malaria treatment employed in the country remains effective. This study clarifies the status of anti-malarial resistance in Ecuador and informs the P. falciparum elimination campaigns in the country.
Topics: Antimalarials; Drug Resistance; Ecuador; Genotype; Humans; Malaria, Falciparum; Parasitic Sensitivity Tests; Phenotype; Plasmodium falciparum; Protozoan Proteins
PubMed: 31822269
DOI: 10.1186/s12936-019-3044-z -
Trends in Parasitology Jun 2021Recent progress in genomics and molecular genetics has empowered novel approaches to study gene functions in disease-causing pathogens. In the human malaria parasite... (Review)
Review
Recent progress in genomics and molecular genetics has empowered novel approaches to study gene functions in disease-causing pathogens. In the human malaria parasite Plasmodium falciparum, the application of genome-based analyses, site-directed genome editing, and genetic systems that allow for temporal and quantitative regulation of gene and protein expression have been invaluable in defining the genetic basis of antimalarial resistance and elucidating candidate targets to accelerate drug discovery efforts. Using examples from recent studies, we review applications of some of these approaches in advancing our understanding of Plasmodium biology and illustrate their contributions and limitations in characterizing parasite genomic loci associated with antimalarial drug responses.
Topics: Antimalarials; Drug Resistance; Genome, Protozoan; Genomics; Humans; Malaria, Falciparum; Molecular Biology; Plasmodium falciparum
PubMed: 33715941
DOI: 10.1016/j.pt.2021.02.007 -
Indian Journal of Medical Microbiology 2020Prohibitins (PHBs) are evolutionarily conserved mitochondrial integral membrane proteins, shown to regulate mitochondrial structure and function, and can be classified...
Prohibitins (PHBs) are evolutionarily conserved mitochondrial integral membrane proteins, shown to regulate mitochondrial structure and function, and can be classified into PHB1 and PHB2. PHB1 and PHB2 have been shown to interact with each other, and form heterodimers in mitochondrial inner membrane. Plasmodium falciparum has orthologues of PHB1 and PHB2 in its genome, and their role is unclear. Here, by homology modelling and yeast two-hybrid analysis, we show that putative Plasmodium PHBs (Pf PHB1 and Pf PHB2) interact with each other, which suggests that they could form supercomplexes of heterodimers in Plasmodium, the functional form required for optimum mitochondrial function.
Topics: Membrane Proteins; Mitochondria; Models, Molecular; Plasmodium falciparum; Prohibitins; Protein Conformation; Protein Multimerization; Protozoan Proteins; Repressor Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Two-Hybrid System Techniques
PubMed: 32883936
DOI: 10.4103/ijmm.IJMM_20_28 -
Trends in Parasitology Sep 2020Occasionally, Plasmodium falciparum malaria is apparently precipitated by traumatic events (e.g., a landmine accident) or by noninfectious events (e.g., pregnancy). The... (Review)
Review
Occasionally, Plasmodium falciparum malaria is apparently precipitated by traumatic events (e.g., a landmine accident) or by noninfectious events (e.g., pregnancy). The authors reporting such cases often seem as baffled as many of their readers probably are. However, the case reports may contain important clues regarding malaria pathogenesis and immunity.
Topics: Humans; Malaria; Plasmodium falciparum; Spleen; Splenic Diseases; Wounds and Injuries
PubMed: 32507384
DOI: 10.1016/j.pt.2020.05.008 -
PloS One 2022Despite ongoing efforts to control malaria infection, progress in lowering the number of deaths and infections appears to have stalled. The continued high incidence of...
Despite ongoing efforts to control malaria infection, progress in lowering the number of deaths and infections appears to have stalled. The continued high incidence of malaria infection and mortality is in part due to emergence of parasites resistant to frontline antimalarials. This highlights the need for continued identification of novel protein drug targets. Mitochondrial functions in Plasmodium falciparum, the deadliest species of human malaria parasite, are targets of validated antimalarials including atovaquone and proguanil (Malarone). Thus, there has been great interest in identifying other essential mitochondrial proteins as candidates for novel drug targets. Garnering an increased understanding of the proteomic landscape inside the P. falciparum mitochondrion will also allow us to learn about the basic biology housed within this unique organelle. We employed a proximity biotinylation technique and mass spectrometry to identify novel P. falciparum proteins putatively targeted to the mitochondrion. We fused the leader sequence of a mitochondrially targeted chaperone, Hsp60, to the promiscuous biotin ligase TurboID. Through these experiments, we generated a list of 122 "putative mitochondrial" proteins. To verify whether these proteins were indeed mitochondrial, we chose five candidate proteins of interest for localization studies using ectopic expression and tagging of each full-length protein. This allowed us to localize four candidate proteins of unknown function to the mitochondrion, three of which have previously been assessed to be essential. We suggest that phenotypic characterization of these and other proteins from this list of 122 could be fruitful in understanding the basic mitochondrial biology of these parasites and aid antimalarial drug discovery efforts.
Topics: Antimalarials; Atovaquone; Biotinylation; Drug Combinations; Humans; Malaria; Malaria, Falciparum; Plasmodium falciparum; Proguanil; Proteomics
PubMed: 35984838
DOI: 10.1371/journal.pone.0273357 -
Proceedings of the National Academy of... Mar 20225-methylcytosine (mC) is an important epitranscriptomic modification involved in messenger RNA (mRNA) stability and translation efficiency in various biological...
5-methylcytosine (mC) is an important epitranscriptomic modification involved in messenger RNA (mRNA) stability and translation efficiency in various biological processes. However, it remains unclear if mC modification contributes to the dynamic regulation of the transcriptome during the developmental cycles of parasites. Here, we characterize the landscape of mC mRNA modifications at single nucleotide resolution in the asexual replication stages and gametocyte sexual stages of rodent () and human () malaria parasites. While different representations of mC-modified mRNAs are associated with the different stages, the abundance of the mC marker is strikingly enhanced in the transcriptomes of gametocytes. Our results show that mC modifications confer stability to the transcripts and that a ortholog of NSUN2 is a major mRNA mC methyltransferase in malaria parasites. Upon knockout of (), marked reductions of mC modification were observed in a panel of gametocytogenesis-associated transcripts. These reductions correlated with impaired gametocyte production in the knockout rodent malaria parasites. Restoration of the gene in the knockout parasites rescued the gametocyte production phenotype as well as mC modification of the gametocytogenesis-associated transcripts. Together with the mRNA mC profiles for two species of , our findings demonstrate a major role for NSUN2-mediated mC modifications in mRNA transcript stability and sexual differentiation in malaria parasites.
Topics: 5-Methylcytosine; Germ Cells; Plasmodium falciparum; Plasmodium yoelii; Protozoan Proteins; RNA, Messenger; Transcriptome
PubMed: 35210361
DOI: 10.1073/pnas.2110713119 -
Parasitology Oct 2020Plasmodium falciparum is the main cause of severe malaria in humans that can lead to death. There is growing evidence of drug-resistance in P. falciparum treatment, and... (Review)
Review
Plasmodium falciparum is the main cause of severe malaria in humans that can lead to death. There is growing evidence of drug-resistance in P. falciparum treatment, and the design of effective vaccines remains an ongoing strategy to control the disease. On the other hand, the recognition of specific diagnostic markers for P. falciparum can accelerate the diagnosis of this parasite in the early stages of infection. Therefore, the identification of novel antigenic proteins especially by proteomic tools is urgent for vaccination and diagnosis of P. falciparum. The proteome diversity of the life cycle stages of P. falciparum, the altered proteome of P. falciparum-infected human sera and altered proteins in P. falciparum-infected erythrocytes could be proposed as appropriate proteins for the aforementioned aims. Accordingly, this review highlights and proposes different proteins identified using proteomic approaches as promising markers in the diagnosis and vaccination of P. falciparum. It seems that most of the candidates identified in this study were able to elicit immune responses in the P. falciparum-infected hosts and they also played major roles in the life cycle, pathogenicity and key pathways of this parasite.
Topics: Animals; Antimalarials; Biomarkers; Drug Resistance; Erythrocytes; Genes, Protozoan; Humans; Life Cycle Stages; Malaria Vaccines; Malaria, Falciparum; Plasmodium falciparum; Proteome; Proteomics; Protozoan Proteins
PubMed: 32618524
DOI: 10.1017/S003118202000102X