Download or read book Analysis of Exported Proteins and Parasite induced Host Cell Rigidity Changes During the Plasmodium Falciparum Intraerythrocxytic Life Cycle written by Beatrice Schibler and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterisation of the Plasmodium Falciparum Export Complex written by Brendan Elsworth and published by . This book was released on 2015 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasmodium parasites extensively remodel the mammalian host cells they infect, namely the erythrocytes and hepatocytes. This is achieved through exporting hundreds of parasite proteins into the host where they play many virulence related roles including altering membrane permeability to acquire nutrients for rapid growth and for increasing immune evasion. Proteins are secreted from the parasite into the vacuole that surrounds them, where they must then pass across the parasitophorous vacuole membrane (PVM) to gain access to the host cytoplasm. It has previously been shown that a protein complex, the Plasmodium Translocon of EXported proteins (PTEX), is found on the PVM and is most likely the protein translocon responsible for this export process. To validate and further dissect PTEX function, a conditional expression system that utilizes the glmS riboswitch was employed to conditionally knockdown the levels of PTEX150 within parasites. Using this approach, even a relatively low level of PTEX150 knockdown lead to a significant decrease in the ability of the parasites to export proteins across the PVM. This failure of protein export across the PVM arrested growth and eventually caused parasite death. Interestingly, the export of all classes of protein cargoes tested, including PfEMP1, were blocked upon PTEX150 knockdown suggesting PTEX may serve as a single portal for export. This demonstrates the importance of PTEX to the malaria parasite and validates it as a potent drug target, since blocking it would prevent hundreds of exported proteins from reaching their functional destinations. To further investigate the specific function of PTEX150 we performed C-terminal truncations in order to generate a parasite line with a partially defective protein. These lines showed destabilisation of the PTEX complex, suggesting that the C-terminus of PTEX150, while not essential for PTEX function or the absolute binding of the other components, is required for stabilising the PTEX complex. Interestingly, these parasites did not show a defect in either their ability to grow or export proteins. To further investigate the effect of PTEX150 knockdown on parasite health the new permeability pathways (NPPs) were investigated. To do this a novel method was developed to investigate NPP function using luciferase. This method is highly sensitive, reducing the amount of parasites required as well as removing the need to purify parasites from culture. The effect of PTEX150 knockdown on NPPs was unclear using this method. Due to the high sensitivity and ease of this method it was developed as a HTS to discover NPP inhibitors. Using this method the malaria box of 400 compounds was screened. Importantly, two compounds, MMV020439and MMV007571, showed inhibitory activity significantly higher than the control compound NPPB.

Download or read book An Alternative Secretory Pathway in the Malaria Parasite Plasmodium falciparum written by Thuvaraka Thavayogarajah and published by GRIN Verlag. This book was released on 2017-08-31 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: Doctoral Thesis / Dissertation from the year 2014 in the subject Biology - Diseases, Health, Nutrition, grade: 1.3, University of Marburg (European virtual Institute for Malaria Research), language: English, abstract: This study focuses on the discovery of an alternative secretory pathway to the ER/Golgi route in the malaria parasite P. falciparum in infected RBCs. Two proteins appeared to be promising candidates of an alternative secretory pathway: the PfADP-ribosylation factor 1 (ARF1) and the Pfadenylate kinase 2 (AK2). Both proteins contained an N-myristoylation site at their N-terminus, which is indicative for N-myristoylation. N-myristoylation is a co-translational modification of a protein, whereby a fatty acid (myristate) is irreversibly attached to the glycine residue at the N-terminus of a protein via the PfN-myristoyltransferase (NMT). A preceding proteomic analysis of the parasitophorous vacuole and a reporter construct study proposed for both PfARF1 (determined by a proteomic study) and PfAK2 (determined by a reporter construct study) PV localization although both proteins lacked a signal peptide. That’s why it was hypothesized whether or not N-myristoylation would drive protein secretion across the parasite plasma membrane (PPM). The subcellular localization of the PfARF1/GFP parasites and the PfAK2/GFP parasites, respectively, were analyzed via epifluorescence microscopy and biochemical methods. In parallel, another batch of reporter constructs were generated and analyzed, where the N-myristoylation site of PfARF1 (this study) and PfAK2 (Ma et al., 2012), respectively, was removed (PfARF1G2A/GFP and PfAK2G2A/GFP). Live cell imaging showed that the fusion protein ARF1/GFP was localized as dot-like structures in the parasite. In contrast, the phenotype of the fusion protein of the PfARF1G2A/GFP parasites showed an evenly distributed signal in the parasite cytosol. Further analysis of the subcellular localization of the PfARF1 strongly supports its localization to compartments of the early secretory pathway of the parasite, but no localization in the PV. In contrast, the fusion protein PfAK2/GFP localized to a ring-like structure around the parasite indicating PV localization. The PfAK2G2A/GFP parasites showed a cytosolic localization of the fusion protein (Ma et al., 2012). Biochemical analyses revaled that the fusion protein PfAK2/GFP was secreted into the PV when the N-myristoylation site was present. Furthermore, it could be shown that the N-terminus of the PfAK2 protein is sufficient for parasite plasma membrane targeting, stable membrane anchoring and subsequent protein translocation across the PPM.

Download or read book Characterization of the Protein Export Steps at the Parasite host Cell Interface of the Human Malaria Parasite Plasmodium Falciparum Welch 1897 written by Paolo Mesén-Ramírez and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Plasmodium Falciparum Exported Protein 1 A Blood Stage Antigen is Expressed in Liver Stage Parasites written by and published by . This book was released on 1994 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: After inoculation by Anopheles sp. mosquitoes, Plasmodium falciparum sporozoites rapidly make their way to the liver where a single, uninucleate sporozoite develops during a minimum of 5-6 days to a mature liver stage schizont with 1-3 x 10(exp 4) uninucleate merozoites. There are no clinical or pathological manifestations associated with this stage of the parasite's life cycle, and thus the parasite developing within the liver is an attractive target for vaccine-induced protective immune responses. Infected hepatocytes are the target of protective immune responses induced by immunization with irradiated sporozoites, sporozoites that develop only partially in hepatocytes. However, so-called 'erythrocytic stage' parasite proteins such as the P. falciparum major merozoite protein-1 (PfMSP-1) are also expressed in infected hepatocytes. As such, they also could be the targets of cellular or humoral immune responses that prevent the release of infectious merozoites from the liver. The current studies were undertaken to determine whether the erythrocytic stage P. falciparum exported protein 1 (Exp-1) is expressed in infected hepatocytes.