Dynamins, or dynamin-related proteins (DRPs), are large mechano-sensitive GTPases that mediate membrane dynamics or organellar fission/fusion events. encodes three dynamin-like proteins whose functions are poorly understood. Here, we demonstrate that one of these dynamin-related proteins, PfDyn2, is required to divide both the apicoplast and the mitochondrion, a striking divergence from the biology of related parasites.
View Article and Find Full Text PDFThe precise mode of action of ganaplacide (KAF156), a phase III antimalarial candidate, remains elusive. Here we employ omics-based methods with the closely related chemical analog, GNF179, to search for potential targets. Ranking potential targets derived from chemical genetics and proteomic affinity chromatography methodologies identifies , or Synthetic Enhancement of YOP1, which is predicted to encode an essential dynamin-like GTPase implicated in homotypic fusion of endoplasmic reticulum (ER) membranes.
View Article and Find Full Text PDFExamining host-pathogen interactions in animals can capture aspects of infection that are obscured in cell culture. Using CRISPR-based screens, we functionally profile the entire genome of the apicomplexan parasite Toxoplasma gondii during murine infection. Barcoded gRNAs enabled bottleneck detection and mapping of population structures within parasite lineages.
View Article and Find Full Text PDFAsexual replication of Plasmodium falciparum occurs via schizogony, wherein 16-36 daughter cells are produced within the parasite during one semi-synchronized cytokinetic event. Schizogony requires a divergent contractile ring structure known as the basal complex. Our lab has previously identified PfMyoJ (PF3D7_1229800) and PfSLACR (PF3D7_0214700) as basal complex proteins recruited midway through segmentation.
View Article and Find Full Text PDFUnlabelled: Condensin I is a pentameric complex that regulates the mitotic chromosome assembly in eukaryotes. The kleisin subunit CAP-H of the condensin I complex acts as a linchpin to maintain the structural integrity and loading of this complex on mitotic chromosomes. This complex is present in all eukaryotes and has recently been identified in spp.
View Article and Find Full Text PDFUnlabelled: Dynamins, or dynamin-related proteins (DRPs), are large mechano-sensitive GTPases mediating membrane dynamics or organellar fission/fusion events. encodes three dynamin-like proteins whose functions are poorly understood. Here, we demonstrate that PfDyn2 mediates both apicoplast and mitochondrial fission.
View Article and Find Full Text PDFCondensin I is a pentameric complex that regulates the mitotic chromosome assembly in eukaryotes. The kleisin subunit CAP-H of the condensin I complex acts as a linchpin to maintain the structural integrity and loading of this complex on mitotic chromosomes. This complex is present in all eukaryotes and has recently been identified in .
View Article and Find Full Text PDFArtemisinin (ART) combination therapies have been critical in reducing malaria morbidity and mortality, but these important drugs are threatened by growing resistance associated with mutations in and . Here, we describe the mechanism of -mediated ART resistance. Coronin interacts with Actin and localizes to the parasite plasma membrane (PPM), the digestive vacuole (DV) membrane, and membrane of a newly identified preDV compartment-all structures involved in the trafficking of hemoglobin from the RBC for degradation in the DV.
View Article and Find Full Text PDFApicomplexan parasites exhibit tremendous diversity in much of their fundamental cell biology, but study of these organisms using light microscopy is often hindered by their small size. Ultrastructural expansion microscopy (U-ExM) is a microscopy preparation method that physically expands the sample by ~4.5×.
View Article and Find Full Text PDFInfection by the parasite is responsible for the most severe form of human malaria. The asexual blood stage of the parasite, which occurs inside human red blood cells, is responsible for the symptoms of malaria and is the target of most antimalarial drugs. spp.
View Article and Find Full Text PDFDuring its asexual blood stage, P. falciparum replicates via schizogony, wherein dozens of daughter cells are formed within a single parent. The basal complex, a contractile ring that separates daughter cells, is critical for schizogony.
View Article and Find Full Text PDFTransmission of the deadly malaria parasite Plasmodium falciparum from humans to mosquitoes is achieved by specialized intraerythrocytic sexual forms called gametocytes. Though the crucial regulatory mechanisms leading to gametocyte commitment have recently come to light, networks of genes that control sexual development remain to be elucidated. Here, we report a pooled-mutant screen to identify genes associated with gametocyte development in P.
View Article and Find Full Text PDFApicomplexan parasites exhibit tremendous diversity in much of their fundamental cell biology, but study of these organisms using light microscopy is often hindered by their small size. Ultrastructural expansion microscopy (U-ExM) is a microscopy preparation method that physically expands the sample ~4.5x.
View Article and Find Full Text PDFWithin a host, pathogens encounter a diverse and changing landscape of cell types, nutrients, and immune responses. Examining host-pathogen interactions in animal models can therefore reveal aspects of infection absent from cell culture. We use CRISPR-based screens to functionally profile the entire genome of the model apicomplexan parasite during mouse infection.
View Article and Find Full Text PDFMalaria remains a global driver of morbidity and mortality. To generate new antimalarials, one must elucidate the fundamental cell biology of , the parasite responsible for the deadliest cases of malaria. A membranous and proteinaceous scaffold called the inner membrane complex (IMC) supports the parasite during morphological changes, including segmentation of daughter cells during asexual replication and formation of transmission-stage gametocytes.
View Article and Find Full Text PDFHuman malaria, caused by infection with parasites, remains one of the most important global public health problems, with the World Health Organization reporting more than 240 million cases and 600,000 deaths annually as of 2020 (). Our understanding of the biology of these parasites is critical for development of effective therapeutics and prophylactics, including both antimalarials and vaccines. is a protozoan organism that is intracellular for most of its life cycle.
View Article and Find Full Text PDFMicroscopic examination of blood smears remains the gold standard for laboratory inspection and diagnosis of malaria. Smear inspection is, however, time-consuming and dependent on trained microscopists with results varying in accuracy. We sought to develop an automated image analysis method to improve accuracy and standardization of smear inspection that retains capacity for expert confirmation and image archiving.
View Article and Find Full Text PDFPlasmodium falciparum, the Apicomplexan parasite that causes the most severe form of human malaria, divides via schizogony during the asexual blood stage of its life cycle. In this method of cell division, multiple daughter cells are generated from a single schizont by segmentation. During segmentation, the basal complex forms at the basal end of the nascent daughter parasites and likely facilitates cell shape and cytokinesis.
View Article and Find Full Text PDFFront Cell Infect Microbiol
July 2021
The actomyosin contractile ring is a key feature of eukaryotic cytokinesis, conserved across many eukaryotic kingdoms. Recent research into the cell biology of the divergent eukaryotic clade Apicomplexa has revealed a contractile ring structure required for asexual division in the medically relevant genera and ; however, the structure of the contractile ring, known as the basal complex in these parasites, remains poorly characterized and in the absence of a myosin II homolog, it is unclear how the force required of a cytokinetic contractile ring is generated. Here, we review the literature on the basal complex in Apicomplexans, summarizing what is known about its formation and function, and attempt to provide possible answers to this question and suggest new avenues of study by comparing the Apicomplexan basal complex to well-studied, established cytokinetic contractile rings and their mechanisms in organisms such as and .
View Article and Find Full Text PDFActivated Vγ9Vδ2 (γδ2) T lymphocytes that sense parasite-produced phosphoantigens are expanded in Plasmodium falciparum-infected patients. Although previous studies suggested that γδ2 T cells help control erythrocytic malaria, whether γδ2 T cells recognize infected red blood cells (iRBCs) was uncertain. Here we show that iRBCs stained for the phosphoantigen sensor butyrophilin 3A1 (BTN3A1).
View Article and Find Full Text PDFThe eukaryotic cell cycle is typically divided into distinct phases with cytokinesis immediately following mitosis. To ensure proper cell division, each phase is tightly coordinated via feedback controls named checkpoints. During its asexual replication cycle, the malaria parasite Plasmodium falciparum undergoes multiple asynchronous rounds of mitosis with segregation of uncondensed chromosomes followed by nuclear division with intact nuclear envelope.
View Article and Find Full Text PDFAsymptomatic carriers of parasites hamper malaria control and eradication. Achieving malaria eradication requires ultrasensitive diagnostics for low parasite density infections (<100 parasites per microliter blood) that work in resource-limited settings (RLS). Sensitive point-of-care diagnostics are also lacking for nonfalciparum malaria, which is characterized by lower density infections and may require additional therapy for radical cure.
View Article and Find Full Text PDFNew techniques for obtaining electron microscopy data through the cell volume are being increasingly utilized to answer cell biologic questions. Here, we present a three-dimensional atlas of Plasmodium falciparum ultrastructure throughout parasite cell division. Multiple wild type schizonts at different stages of segmentation, or budding, were imaged and rendered, and the 3D structure of their organelles and daughter cells are shown.
View Article and Find Full Text PDFMalaria caused by Plasmodium falciparum remains the leading single-agent cause of mortality in children, yet the promise of an effective vaccine has not been fulfilled. Here, using our previously described differential screening method to analyse the proteome of blood-stage P. falciparum parasites, we identify P.
View Article and Find Full Text PDFProtein kinases are important mediators of signal transduction in cellular pathways, and calcium-dependent protein kinases (CDPKs) compose a unique class of calcium-dependent kinases present in plants and apicomplexans, including parasites, the causative agents of malaria. During the asexual stage of infection, the human malaria parasite grows inside red blood cells, and calcium-dependent protein kinase 5 (PfCDPK5) is required for egress from the host cell. In this paper, we characterize the late-schizont-stage phosphoproteome by performing large-scale phosphoproteomic profiling on tightly synchronized parasites just prior to egress, identifying 2,704 phosphorylation sites on 919 proteins.
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