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  1. Article ; Online: Regulation of Atg8 membrane deconjugation by cysteine proteases in the malaria parasite Plasmodium berghei.

    Mishra, Akancha / Varshney, Aastha / Mishra, Satish

    Cellular and molecular life sciences : CMLS

    2023  Volume 80, Issue 11, Page(s) 344

    Abstract: During macroautophagy, the Atg8 protein is conjugated to phosphatidylethanolamine (PE) in autophagic membranes. In Apicomplexan parasites, two cysteine proteases, Atg4 and ovarian tumor unit (Otu), have been identified to delipidate Atg8 to release this ... ...

    Abstract During macroautophagy, the Atg8 protein is conjugated to phosphatidylethanolamine (PE) in autophagic membranes. In Apicomplexan parasites, two cysteine proteases, Atg4 and ovarian tumor unit (Otu), have been identified to delipidate Atg8 to release this protein from membranes. Here, we investigated the role of cysteine proteases in Atg8 conjugation and deconjugation and found that the Plasmodium parasite consists of both activities. We successfully disrupted the genes individually; however, simultaneously, they were refractory to deletion and essential for parasite survival. Mutants lacking Atg4 and Otu showed normal blood and mosquito stage development. All mice infected with Otu KO sporozoites became patent; however, Atg4 KO sporozoites either failed to establish blood infection or showed delayed patency. Through in vitro and in vivo analysis, we found that Atg4 KO sporozoites invade and normally develop into early liver stages. However, nuclear and organelle differentiation was severely hampered during late stages and failed to mature into hepatic merozoites. We found a higher level of Atg8 in Atg4 KO parasites, and the deconjugation of Atg8 was hampered. We confirmed Otu localization on the apicoplast; however, parasites lacking Otu showed no visible developmental defects. Our data suggest that Atg4 is the primary deconjugating enzyme and that Otu cannot replace its function completely because it cleaves the peptide bond at the N-terminal side of glycine, thereby irreversibly inactivating Atg8 during its recycling. These findings highlight a role for the Atg8 deconjugation pathway in organelle biogenesis and maintenance of the homeostatic cellular balance.
    MeSH term(s) Animals ; Mice ; Cysteine Proteases/genetics ; Cysteine Proteases/metabolism ; Parasites/metabolism ; Plasmodium berghei ; Autophagy-Related Protein 8 Family/genetics ; Autophagy-Related Protein 8 Family/metabolism ; Autophagy ; Malaria ; Protozoan Proteins/metabolism
    Chemical Substances Cysteine Proteases (EC 3.4.-) ; Autophagy-Related Protein 8 Family ; Protozoan Proteins
    Language English
    Publishing date 2023-11-01
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 1358415-7
    ISSN 1420-9071 ; 1420-682X
    ISSN (online) 1420-9071
    ISSN 1420-682X
    DOI 10.1007/s00018-023-05004-2
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Stearoyl-CoA desaturase regulates organelle biogenesis and hepatic merozoite formation in Plasmodium berghei.

    Narwal, Sunil Kumar / Mishra, Akancha / Devi, Raksha / Ghosh, Ankit / Choudhary, Hadi Hasan / Mishra, Satish

    Molecular microbiology

    2024  Volume 121, Issue 5, Page(s) 940–953

    Abstract: Plasmodium is an obligate intracellular parasite that requires intense lipid synthesis for membrane biogenesis and survival. One of the principal membrane components is oleic acid, which is needed to maintain the membrane's biophysical properties and ... ...

    Abstract Plasmodium is an obligate intracellular parasite that requires intense lipid synthesis for membrane biogenesis and survival. One of the principal membrane components is oleic acid, which is needed to maintain the membrane's biophysical properties and fluidity. The malaria parasite can modify fatty acids, and stearoyl-CoA Δ9-desaturase (Scd) is an enzyme that catalyzes the synthesis of oleic acid by desaturation of stearic acid. Scd is dispensable in P. falciparum blood stages; however, its role in mosquito and liver stages remains unknown. We show that P. berghei Scd localizes to the ER in the blood and liver stages. Disruption of Scd in the rodent malaria parasite P. berghei did not affect parasite blood stage propagation, mosquito stage development, or early liver-stage development. However, when Scd KO sporozoites were inoculated intravenously or by mosquito bite into mice, they failed to initiate blood-stage infection. Immunofluorescence analysis revealed that organelle biogenesis was impaired and merozoite formation was abolished, which initiates blood-stage infections. Genetic complementation of the KO parasites restored merozoite formation to a level similar to that of WT parasites. Mice immunized with Scd KO sporozoites confer long-lasting sterile protection against infectious sporozoite challenge. Thus, the Scd KO parasite is an appealing candidate for inducing protective pre-erythrocytic immunity and hence its utility as a GAP.
    MeSH term(s) Plasmodium berghei/genetics ; Plasmodium berghei/growth & development ; Plasmodium berghei/metabolism ; Plasmodium berghei/enzymology ; Animals ; Mice ; Organelle Biogenesis ; Liver/parasitology ; Merozoites/growth & development ; Merozoites/metabolism ; Malaria/parasitology ; Stearoyl-CoA Desaturase/metabolism ; Stearoyl-CoA Desaturase/genetics ; Sporozoites/growth & development ; Sporozoites/metabolism ; Protozoan Proteins/metabolism ; Protozoan Proteins/genetics ; Anopheles/parasitology ; Female ; Endoplasmic Reticulum/metabolism
    Language English
    Publishing date 2024-02-28
    Publishing country England
    Document type Journal Article
    ZDB-ID 619315-8
    ISSN 1365-2958 ; 0950-382X
    ISSN (online) 1365-2958
    ISSN 0950-382X
    DOI 10.1111/mmi.15246
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Secreted protein with altered thrombospondin repeat (SPATR) is essential for asexual blood stages but not required for hepatocyte invasion by the malaria parasite Plasmodium berghei.

    Gupta, Roshni / Mishra, Akancha / Choudhary, Hadi Hasan / Narwal, Sunil Kumar / Nayak, Bandita / Srivastava, Pratik Narain / Mishra, Satish

    Molecular microbiology

    2019  Volume 113, Issue 2, Page(s) 478–491

    Abstract: Upon entering its mammalian host, the malaria parasite productively invades two distinct cell types, that is, hepatocytes and erythrocytes during which several adhesins/invasins are thought to be involved. Many surface-located proteins containing ... ...

    Abstract Upon entering its mammalian host, the malaria parasite productively invades two distinct cell types, that is, hepatocytes and erythrocytes during which several adhesins/invasins are thought to be involved. Many surface-located proteins containing thrombospondin Type I repeat (TSR) which help establish host-parasite molecular crosstalk have been shown to be essential for mammalian infection. Previous reports indicated that antibodies produced against Plasmodium falciparum secreted protein with altered thrombospondin repeat (SPATR) block hepatocyte invasion by sporozoites but no genetic evidence of its contribution to invasion has been reported. After failing to generate Spatr knockout in Plasmodium berghei blood stages, a conditional mutagenesis system was employed. Here, we show that SPATR plays an essential role during parasite's blood stages. Mutant salivary gland sporozoites exhibit normal motility, hepatocyte invasion, liver stage development and rupture of the parasitophorous vacuole membrane resulting in merosome formation. But these mutant hepatic merozoites failed to establish a blood stage infection in vivo. We provide direct evidence that SPATR is not required for hepatocyte invasion but plays an essential role during the blood stages of P. berghei.
    MeSH term(s) Animals ; Erythrocytes/parasitology ; Gene Knockout Techniques ; Hepatocytes/parasitology ; Host-Parasite Interactions ; Malaria/parasitology ; Membrane Proteins/genetics ; Membrane Proteins/metabolism ; Merozoites/metabolism ; Phylogeny ; Plasmodium berghei/genetics ; Plasmodium berghei/metabolism ; Protozoan Proteins/genetics ; Protozoan Proteins/metabolism ; Sporozoites/metabolism ; Thrombospondins/genetics ; Thrombospondins/metabolism
    Chemical Substances Membrane Proteins ; Protozoan Proteins ; SPATR protein, Plasmodium falciparum ; Thrombospondins
    Language English
    Publishing date 2019-12-11
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 619315-8
    ISSN 1365-2958 ; 0950-382X
    ISSN (online) 1365-2958
    ISSN 0950-382X
    DOI 10.1111/mmi.14432
    Database MEDical Literature Analysis and Retrieval System OnLINE

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