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Malaria Journal Nov 2017Post-translational modifications (PTMs) constitute a huge group of chemical modifications increasing the complexity of the proteomes of living beings. PTMs have been...
BACKGROUND
Post-translational modifications (PTMs) constitute a huge group of chemical modifications increasing the complexity of the proteomes of living beings. PTMs have been discussed as potential anti-malarial drug targets due to their involvement in many cell processes. O-GlcNAcylation is a widespread PTM found in different organisms including Plasmodium falciparum. The aim of this study was to identify O-GlcNAcylated proteins of P. falciparum, to learn more about the modification process and to understand its eventual functions in the Apicomplexans.
METHODS
The P. falciparum strain 3D7 was amplified in erythrocytes and purified. The proteome was checked for O-GlcNAcylation using different methods. The level of UDP-GlcNAc, the donor of the sugar moiety for O-GlcNAcylation processes, was measured using high-pH anion exchange chromatography. O-GlcNAcylated proteins were enriched and purified utilizing either click chemistry labelling or adsorption on succinyl-wheat germ agglutinin beads. Proteins were then identified by mass-spectrometry (nano-LC MS/MS).
RESULTS
While low when compared to MRC5 control cells, P. falciparum disposes of its own pool of UDP-GlcNAc. By using proteomics methods, 13 O-GlcNAcylated proteins were unambiguously identified (11 by click-chemistry and 6 by sWGA-beads enrichment; 4 being identified by the 2 approaches) in late trophozoites. These proteins are all part of pathways, functions and structures important for the parasite survival. By probing clicked-proteins with specific antibodies, Hsp70 and α-tubulin were identified as P. falciparum O-GlcNAc-bearing proteins.
CONCLUSIONS
This study is the first report on the identity of P. falciparum O-GlcNAcylated proteins. While the parasite O-GlcNAcome seems close to those of other species, the structural differences exhibited by the proteomes provides a glimpse of innovative therapeutic paths to fight malaria. Blocking biosynthesis of UDP-GlcNAc in the parasites is another promising option to reduce Plasmodium life cycle.
Topics: Acetylglucosamine; Glycosylation; Plasmodium falciparum; Protein Processing, Post-Translational; Proteome; Protozoan Proteins
PubMed: 29187233
DOI: 10.1186/s12936-017-2131-2 -
Parasitology Research Jun 2020RbAp46/RBBP7 and RbAp48/RBBP4 are WD40-repeat histone chaperones and chromatin adaptors that reside in multiple complexes involved in maintenance of chromatin structure....
RbAp46/RBBP7 and RbAp48/RBBP4 are WD40-repeat histone chaperones and chromatin adaptors that reside in multiple complexes involved in maintenance of chromatin structure. RbAp48 is the essential subunit of the chromatin assembly factor-1 (CAF-1) complex, therefore also named as CAF-1C. A detailed in silico sequence and structure analysis of homologs of RbAp46/48 in Plasmodium falciparum (PF3D7_0110700 and PF3D7_1433300) exhibited conservation of characteristic features in both the protein-seven-bladed WD40 β-propeller conformation and different binding interfaces. A comparative structural analysis highlighted species-specific features of the parasite, yeast, drosophila, and human RbAp46/48. In the present study, we report cloning, expression, and characterization of P. falciparum PF3D7_0110700, a putative RbAp46/48 (PfRbAp46/48). PfRbAp46/48 was cloned into pTEM11 vector in fusion with 6xHistidine tag and over-expressed in Escherichia coli B834 cells. The protein was purified by Ni-NTA followed by gel permeation chromatography. The protein expressed in all the three asexual blood stages and exhibited nuclear localization. We showed direct interaction of the purified rPfRbAp46/48 with the histone H4. These findings further our understanding of RbAp46/48 proteins and role of these proteins in the parasite biology.
Topics: Amino Acid Sequence; Cell Nucleus; Chromatin; Gene Expression; Histone Chaperones; Histones; Life Cycle Stages; Plasmodium falciparum; Protein Binding; Protein Conformation; Protozoan Proteins; Recombinant Fusion Proteins
PubMed: 32363442
DOI: 10.1007/s00436-020-06669-5 -
Malaria Journal Dec 2021The devastating public health impact of malaria has prompted the need for effective interventions. Malaria control gained traction after the introduction of... (Review)
Review
BACKGROUND
The devastating public health impact of malaria has prompted the need for effective interventions. Malaria control gained traction after the introduction of artemisinin-based combination therapy (ACT). However, the emergence of artemisinin (ART) partial resistance in Southeast Asia and emerging reports of delayed parasite sensitivity to ACT in African parasites signal a gradual trend towards treatment failure. Monitoring the prevalence of mutations associated with artemisinin resistance in African populations is necessary to stop resistance in its tracks. Mutations in Plasmodium falciparum genes pfk13, pfcoronin and pfatpase6 have been linked with ART partial resistance.
METHODS
Findings from published research articles on the prevalence of pfk13, pfcoronin and pfatpase6 polymorphisms in Africa were collated. PubMed, Embase and Google Scholar were searched for relevant articles reporting polymorphisms in these genes across Africa from 2014 to August 2021, for pfk13 and pfcoronin. For pfatpase6, relevant articles between 2003 and August 2021 were retrieved.
RESULTS
Eighty-seven studies passed the inclusion criteria for this analysis and reported 742 single nucleotide polymorphisms in 37,864 P. falciparum isolates from 29 African countries. Five validated-pfk13 partial resistance markers were identified in Africa: R561H in Rwanda and Tanzania, M476I in Tanzania, F446I in Mali, C580Y in Ghana, and P553L in an Angolan isolate. In Tanzania, three (L263E, E431K, S769N) of the four mutations (L263E, E431K, A623E, S769N) in pfatpase6 gene associated with high in vitro IC were reported. pfcoronin polymorphisms were reported in Senegal, Gabon, Ghana, Kenya, and Congo, with P76S being the most prevalent mutation.
CONCLUSIONS
This meta-analysis provides an overview of the prevalence and widespread distribution of pfk13, pfcoronin and pfatpase6 mutations in Africa. Understanding the phenotypic consequences of these mutations can provide information on the efficacy status of artemisinin-based treatment of malaria across the continent.
Topics: Adenosine Triphosphatases; Antimalarials; Artemisinins; Drug Resistance; Microfilament Proteins; Plasmodium falciparum; Protozoan Proteins
PubMed: 34856982
DOI: 10.1186/s12936-021-03987-6 -
The Biochemical Journal Aug 2014Despite a century of control and eradication campaigns, malaria remains one of the world's most devastating diseases. Our once-powerful therapeutic weapons are losing... (Review)
Review
Despite a century of control and eradication campaigns, malaria remains one of the world's most devastating diseases. Our once-powerful therapeutic weapons are losing the war against the Plasmodium parasite, whose ability to rapidly develop and spread drug resistance hamper past and present malaria-control efforts. Finding new and effective treatments for malaria is now a top global health priority, fuelling an increase in funding and promoting open-source collaborations between researchers and pharmaceutical consortia around the world. The result of this is rapid advances in drug discovery approaches and technologies, with three major methods for antimalarial drug development emerging: (i) chemistry-based, (ii) target-based, and (iii) cell-based. Common to all three of these approaches is the unique ability of structural biology to inform and accelerate drug development. Where possible, SBDD (structure-based drug discovery) is a foundation for antimalarial drug development programmes, and has been invaluable to the development of a number of current pre-clinical and clinical candidates. However, as we expand our understanding of the malarial life cycle and mechanisms of resistance development, SBDD as a field must continue to evolve in order to develop compounds that adhere to the ideal characteristics for novel antimalarial therapeutics and to avoid high attrition rates pre- and post-clinic. In the present review, we aim to examine the contribution that SBDD has made to current antimalarial drug development efforts, covering hit discovery to lead optimization and prevention of parasite resistance. Finally, the potential for structural biology, particularly high-throughput structural genomics programmes, to identify future targets for drug discovery are discussed.
Topics: Animals; Antimalarials; Drug Discovery; Drug Resistance, Multiple; Humans; Life Cycle Stages; Models, Biological; Molecular Structure; Plasmodium falciparum; Protozoan Proteins
PubMed: 25008945
DOI: 10.1042/BJ20140240 -
Malaria Journal May 2018In Thailand, artemisinin-based combination therapy (ACT) has been used to treat uncomplicated falciparum malaria since 1995. Unfortunately, artemisinin resistance has...
BACKGROUND
In Thailand, artemisinin-based combination therapy (ACT) has been used to treat uncomplicated falciparum malaria since 1995. Unfortunately, artemisinin resistance has been reported from Thailand and other Southeast Asian countries since 2003. Malarone, a combination of atovaquone-proguanil (ATQ-PG), has been used to cease artemisinin pressure in some areas along Thai-Cambodia border, as part of an artemisinin resistance containment project since 2009. This study aimed to determine genotypes and phenotypes of Plasmodium falciparum isolates collected from the Thai-Cambodia border after the artemisinin resistance containment project compared with those collected before.
RESULTS
One hundred and nine of P. falciparum isolates collected from Thai-Cambodia border from Chanthaburi and Trat provinces during 1988-2016 were used in this study. Of these, 58 isolates were collected after the containment. These parasite isolates were characterized for in vitro antimalarial sensitivities including chloroquine (CQ), quinine (QN), mefloquine (MQ), piperaquine (PPQ), artesunate (AS), dihydroartemisinin (DHA), ATQ and PG and genetic markers for drug resistance including the Kelch13 (k13), Plasmodium falciparum chloroquine resistance transporter (pfcrt), P. falciparum multidrug resistance 1 (pfmdr1) and cytochrome b (cytb) genes. Mean CQ, QN, MQ, PPQ and AS ICs of the parasite isolates collected from 2009 to 2016 exhibited significantly higher than those of parasites collected before 2009. Approximately 57% exhibited in vitro MQ resistance. Approximately 94% of the isolates collected from 2009 to 2016 contained the pfmdr1 184F allele. Mutations of the k13 gene were detected in approximately 90% of the parasites collected from 2009 to 2016 which were significantly higher than the parasite isolates collected before. No ATQ-resistant genotype and phenotype of P. falciparum were found among the isolates collected after the containment project.
CONCLUSIONS
Although the containment project had been implemented in this area, the expansion of artemisinin-resistant parasites did not decline. In addition, reduced sensitivity of the partner drugs of ACT including MQ and PPQ were identified.
Topics: Antimalarials; Artemisinins; Drug Resistance; Genotype; Phenotype; Plasmodium falciparum; Thailand
PubMed: 29764451
DOI: 10.1186/s12936-018-2347-9 -
Nucleic Acids Research Feb 2017For reasons that remain unknown, the Plasmodium falciparum genome has an exceptionally high AT content compared to other Plasmodium species and eukaryotes in general -...
For reasons that remain unknown, the Plasmodium falciparum genome has an exceptionally high AT content compared to other Plasmodium species and eukaryotes in general - nearly 80% in coding regions and approaching 90% in non-coding regions. Here, we examine how this phenomenon relates to genome-wide patterns of de novo mutation. Mutation accumulation experiments were performed by sequential cloning of six P. falciparum isolates growing in human erythrocytes in vitro for 4 years, with 279 clones sampled for whole genome sequencing at different time points. Genome sequence analysis of these samples revealed a significant excess of G:C to A:T transitions compared to other types of nucleotide substitution, which would naturally cause AT content to equilibrate close to the level seen across the P. falciparum reference genome (80.6% AT). These data also uncover an extremely high rate of small indel mutation relative to other species, primarily associated with repetitive AT-rich sequences, in addition to larger-scale structural rearrangements focused in antigen-coding var genes. In conclusion, high AT content in P. falciparum is driven by a systematic mutational bias and ultimately leads to an unusual level of microstructural plasticity, raising the question of whether this contributes to adaptive evolution.
Topics: Base Composition; Gene Expression Regulation; Genome, Protozoan; INDEL Mutation; Mutation; Mutation Rate; Phylogeny; Plasmodium falciparum; Polymorphism, Single Nucleotide; Recombination, Genetic; Reproducibility of Results
PubMed: 27994033
DOI: 10.1093/nar/gkw1259 -
Cells Apr 2022The global burden of malaria and toxoplasmosis has been limited by the use of efficacious anti-parasitic agents, however, emerging resistance in species and threatens...
The global burden of malaria and toxoplasmosis has been limited by the use of efficacious anti-parasitic agents, however, emerging resistance in species and threatens disease control worldwide, implying that new agents/therapeutic targets are urgently needed. Nuclear localization signal (NLS)-dependent transport into the nucleus, mediated by members of the importin (IMP) superfamily of nuclear transporters, has shown potential as a target for intervention to limit viral infection. Here, we show for the first time that IMPα from and have promise as targets for small molecule inhibitors. We use high-throughput screening to identify agents able to inhibit IMPα binding to a NLS, identifying a number of compounds that inhibit binding in the µM-nM range, through direct binding to IMPα, as shown in thermostability assays. Of these, BAY 11-7085 is shown to be a specific inhibitor of IMPα-NLS recognition. Importantly, a number of the inhibitors limited growth by both and . The results strengthen the hypothesis that apicomplexan IMPα proteins have potential as therapeutic targets to aid in identifying novel agents for two important, yet neglected, parasitic diseases.
Topics: High-Throughput Screening Assays; Nuclear Localization Signals; Plasmodium falciparum; Protein Binding; alpha Karyopherins
PubMed: 35406765
DOI: 10.3390/cells11071201 -
Microbiology Spectrum Feb 2022Cholesterol is the most abundant lipid in the erythrocyte. During its blood-stage development, the malaria parasite establishes an active cholesterol gradient across the...
Cholesterol is the most abundant lipid in the erythrocyte. During its blood-stage development, the malaria parasite establishes an active cholesterol gradient across the various membrane systems within the infected erythrocyte. Interestingly, some antimalarial compounds have recently been shown to disrupt cholesterol homeostasis in the intraerythrocytic stages of Plasmodium falciparum. These studies point to the importance of cholesterol for parasite growth. Previously, reduction of cholesterol from the erythrocyte membrane by treatment with methyl-β-cyclodextrin (MβCD) was shown to inhibit parasite invasion and growth. In addition, MβCD treatment of trophozoite-stage P. falciparum was shown to result in parasite expulsion from the host cell. We have revisited these phenomena by using live video microscopy, ultrastructural analysis, and response to antimalarial compounds. By using time-lapse video microscopy of fluorescently tagged parasites, we show that MβCD treatment for just 30 min causes dramatic expulsion of the trophozoite-stage parasites. This forceful expulsion occurs within 10 s. Remarkably, the plasma membrane of the host cell from which the parasite has been expelled does not appear to be compromised. The parasitophorous vacuolar membrane (PVM) continued to surround the extruded parasite, but the PVM appeared damaged. Treatment with antimalarial compounds targeting PfATP4 or PfNCR1 prevented MβCD-mediated extrusion of the parasites, pointing to a potential role of cholesterol dynamics underlying the expulsion phenomena. We also confirmed the essential role of erythrocyte plasma membrane cholesterol for invasion and growth of P. falciparum. This defect can be partially complemented by cholesterol and desmosterol but not with epicholesterol, revealing stereospecificity underlying cholesterol function. Overall, our studies advance previous observations and reveal unusual cell biological features underlying cholesterol depletion of the infected erythrocyte plasma membrane. Malaria remains a major challenge in much of the world. Symptoms of malaria are caused by the growth of parasites belonging to spp. inside the red blood cells (RBCs), leading to their destruction. The parasite depends upon its host for much of its nutritional needs. Cholesterol is a major lipid in the RBC plasma membrane, which is the only source of this lipid for malaria parasites. We have previously shown that certain new antimalarial compounds disrupt cholesterol homeostasis in P. falciparum. Here, we use live time-lapse video microscopy to show dramatic expulsion of the parasite from the host RBC when the cholesterol content of the RBC is reduced. Remarkably, this expulsion is inhibited by the antimalarials that disrupt lipid homeostasis. We also show stereospecificity of cholesterol in supporting parasite growth inside RBC. Overall, these results point to a critical role of cholesterol in the physiology of malaria parasites.
Topics: Antimalarials; Cholesterol; Erythrocyte Membrane; Erythrocytes; Humans; Malaria, Falciparum; Plasmodium falciparum; Protozoan Proteins; beta-Cyclodextrins
PubMed: 35196803
DOI: 10.1128/spectrum.00158-22 -
Scientific Reports Feb 2021Cytoskeletal structures of Apicomplexan parasites are important for parasite replication, motility, invasion to the host cell and survival. Apicortin, an Apicomplexan...
Cytoskeletal structures of Apicomplexan parasites are important for parasite replication, motility, invasion to the host cell and survival. Apicortin, an Apicomplexan specific protein appears to be a crucial factor in maintaining stability of the parasite cytoskeletal assemblies. However, the function of apicortin, in terms of interaction with microtubules still remains elusive. Herein, we have attempted to elucidate the function of Plasmodium falciparum apicortin by monitoring its interaction with two main components of parasite microtubular structure, α-tubulin-I and β-tubulin through in silico and in vitro studies. Further, a p25 domain binding generic drug Tamoxifen (TMX), was used to disrupt PfApicortin-tubulin interactions which led to the inhibition in growth and progression of blood stage life cycle of P. falciparum.
Topics: Adaptor Proteins, Signal Transducing; Microtubules; Plasmodium falciparum; Protein Binding; Protozoan Proteins; Tubulin
PubMed: 33633135
DOI: 10.1038/s41598-021-83513-5 -
Trends in Parasitology Sep 2022The recent study by Campelo Morillo et al. has shown that one of the small number of non-ApiAP2 DNA-binding proteins in the Plasmodium falciparum genome acts as a...
The recent study by Campelo Morillo et al. has shown that one of the small number of non-ApiAP2 DNA-binding proteins in the Plasmodium falciparum genome acts as a transcription factor in the gametocytogenesis cascade and is responsible for the gametocyte's distinctive morphology.
Topics: Gene Expression Regulation; Plasmodium falciparum; Transcription Factors
PubMed: 35871979
DOI: 10.1016/j.pt.2022.07.004