An exported protein of Plasmodium falciparum is synthesized as an integral membrane protein

Günther, Kathrin; Tümmler, Meike; Arnold, H.H.; Ridley, Robert G.; Goman, Michael; Scaife, John; Lingelbach, Klaus

doi:10.1016/0166-6851(91)90208-n

Cited by 112 publications

(90 citation statements)

References 19 publications

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“…1A), which localizes to the PVM (34,37). Because EXP-1 CT is known to be exposed to the host cell cytoplasm (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…It harbors a classical N-terminal signal peptide, and, upon trafficking via the endoplasmic reticulum-Golgi transport route, is inserted with its transmembrane domain into the PVM of both blood and liver parasite stages (29)(30)(31)(32)(33). It was shown later that the protein's N-terminal region faces the PV lumen, whereas its C terminus (CT) extends into the host-cell cytosol (34,35). The same membrane topology was reported for other small PVM-resident proteins of the ETRAMP family, which are, together with EXP-1, organized in nonoverlapping oligomeric arrays within the PVM (36,37).…”

Section: Significancementioning

confidence: 99%

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Plasmodium berghei EXP-1 interacts with host Apolipoprotein H during Plasmodium liver-stage development

Cunha

Nyboer

Heiß

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The first, obligatory replication phase of malaria parasite infections is characterized by rapid expansion and differentiation of single parasites in liver cells, resulting in the formation and release of thousands of invasive merozoites into the bloodstream. Hepatic Plasmodium development occurs inside a specialized membranous compartment termed the parasitophorous vacuole (PV). Here, we show that, during the parasite's hepatic replication, the C-terminal region of the parasitic PV membrane protein exported protein 1 (EXP-1) binds to host Apolipoprotein H (ApoH) and that this molecular interaction plays a pivotal role for successful Plasmodium liver-stage development. Expression of a truncated EXP-1 protein, missing the specific ApoH interaction site, or down-regulation of ApoH expression in either hepatic cells or mouse livers by RNA interference resulted in impaired intrahepatic development. Furthermore, infection of mice with sporozoites expressing a truncated version of EXP-1 resulted in both a significant reduction of liver burden and delayed blood-stage patency, leading to a disease outcome different from that generally induced by infection with wildtype parasites. This study identifies a host-parasite protein interaction during the hepatic stage of infection by Plasmodium parasites. The identification of such vital interactions may hold potential toward the development of novel malaria prevention strategies. malaria | Plasmodium liver stages | host-parasite interaction | ApoH | EXP-1

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“…1A), which localizes to the PVM (34,37). Because EXP-1 CT is known to be exposed to the host cell cytoplasm (Fig.…”

Section: Resultsmentioning

confidence: 99%

Section: Significancementioning

confidence: 99%

Plasmodium berghei EXP-1 interacts with host Apolipoprotein H during Plasmodium liver-stage development

Cunha

Nyboer

Heiß

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…A mAb specific for PfExp-1, mAbN1 (17), PfExp-1 polyclonal sera, and human sera from individuals resident in an endemic area recognize COS cells transfected with PyHEP17Ex1.2 plasmid DNA and react with P. yoelii-infected liver-stage and blood-stage parasites (data not presented). Although the minimal epitope on PfExp-1 has not been defined, mAbN1 recognizes an epitope between amino acids 23 and 75 (17). Given the antigenic cross-reactivity reported here, the mAbN1 epitope is likely to map between amino acids 44 and 65 of PfExp-1 where 16/22 amino acids are identical to the homologous region of PyHEP17 (Fig.…”

Section: Fig 4 Identity Between Pyhep17 and Pfexp-1 Revealed By Alimentioning

confidence: 91%

Identification and Characterization of the Protective Gene of homolog of Exported Protein 1

Doolan

Hedstrom

Rogers

et al. 1996

Journal of Biological Chemistry

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We recently reported the discovery of a 17-kDa Plasmodium yoelii protein expressed in infected hepatocytes and erythrocytes, P. yoelii hepatocyte erythrocyte protein 17 (PyHEP17), and have demonstrated that this protein is a target of protective antibodies and T cells. Here, we report the identification and characterization of the gene encoding this protein and reveal that it is composed of two exons. Immunization of mice with Py-HEP17 plasmid DNA induces antibodies, cytotoxic T lymphocytes, and protective immunity directed against the infected hepatocyte. Based on extensive sequence homology, expression pattern, and antigenic cross-reactivity, the Plasmodium falciparum homolog of PyHEP17 is identified as the protein known as exported protein-1 (PfExp-1), also called antigen 5.1, circumsporozoite related antigen, or QF116. Identity between PyHEP17 and PfExp-1 is 37% at the amino acid level (60/161 residues), mapping primarily to two regions within the second exon of 73% (16/22 residues) and 71% (25/35 residues) identity. On this basis, PfExp-1 is proposed as an important component of pre-erythrocytic human malaria vaccines.

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“…To investigate whether transport across the PVM requires sequences specific to exported parasite proteins, luciferase was fused to the 26 N-terminal amino acids of the precursor of EXP1, a protein that is anchored within the PVM via an internal stop transfer sequence (14,30). The secretory signal sequence was chosen because (i) it directs EXP1 into the secretory pathway in both the parasite and a reconstituted heterologous in vitro system (14) and (ii) N-terminal sequencing of the mature protein had revealed a signal peptidase cleavage site at Ala-22-Glu-23 (31).…”

Section: Table I Luciferase Activity In Different Subcellular Fractiomentioning

confidence: 99%

“…The secretory signal sequence was chosen because (i) it directs EXP1 into the secretory pathway in both the parasite and a reconstituted heterologous in vitro system (14) and (ii) N-terminal sequencing of the mature protein had revealed a signal peptidase cleavage site at Ala-22-Glu-23 (31). Thus, the N-terminal signal sequence is removed from the mature protein in the parasite endoplasmic reticulum where signal peptide cleavage occurs.…”

Section: Table I Luciferase Activity In Different Subcellular Fractiomentioning

confidence: 99%

Luciferase, When Fused to an N-terminal Signal Peptide, Is Secreted from Transfected Plasmodium falciparum and Transported to the Cytosol of Infected Erythrocytes

Burghaus

Lingelbach

2001

Journal of Biological Chemistry

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Plasmodium falciparum, a unicellular parasite that causes human malaria, infects erythrocytes where it develops within a vacuole. The vacuolar membrane separates the parasite from the erythrocyte cytosol. Some secreted parasite proteins remain inside the vacuole, and others are transported across the vacuolar membrane. To identify the protein sequences responsible for this distribution we investigated the suitability of the green fluorescent protein and luciferase as reporters in transiently transfected parasites. Because of the higher sensitivity of the enzymatic assay, luciferase was quantified 3 days after transfection, whereas reliable detection of green fluorescent protein required prolonged drug selection. Luciferase was confined to the parasite cytosol in subcellular fractions of infected erythrocytes. When parasites were transfected with a hybrid gene coding for the cleavable N-terminal signal peptide of a secreted parasite protein fused to luciferase, the reporter protein was secreted. It was recovered with the vacuolar content and the erythrocyte cytosol. The results suggest that no specific protein sequences are required for translocation across the vacuolar membrane. The high local concentration of luciferase within the vacuole argues against free diffusion, and thus transport into the erythrocyte cytosol must involve a ratelimiting step.Plasmodium falciparum, the parasite that causes the most severe form of malaria, spends part of its life cycle in human erythrocytes. Here it resides within the so-called parasitophorous vacuole, which is bound by the parasitophorous vacuolar membrane (PVM).1 The vacuole constitutes a separate compartment in the infected red blood cell (iRBC) that is distinct from the cytosol of the parasite and from the cytosol of the erythrocyte, respectively (1). Most proteins secreted from P. falciparum are not released into an extracellular space but are transported to various destinations within the iRBC: the parasitophorous vacuole or the erythrocyte cytosol. Membranebound proteins are found in the PVM and erythrocyte plasma membrane (2, 3). It is completely unknown which information within a polypeptide chain determines whether a protein is transported across the PVM. Recently we described experimental evidence for a transport pathway that involves the release of secreted parasite proteins into the vacuolar space and translocation across the PVM in a subsequent step (4). This model infers that a sorting mechanism must operate within the vacuole that discriminates between vacuolar resident proteins and proteins destined for a location beyond the PVM (5). Sorting could involve two different principles: the retention of vacuolar proteins or, alternatively, the recognition of protein signals that mediate translocation across the PVM.A widely used experimental approach for the identification of protein targeting and sorting signals in eukaryotic cells is the fusion of putative signal sequences to reporter proteins and their subsequent localization in the transfected cell. Although...

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An exported protein of Plasmodium falciparum is synthesized as an integral membrane protein

Cited by 112 publications

References 19 publications

Plasmodium berghei EXP-1 interacts with host Apolipoprotein H during Plasmodium liver-stage development

Plasmodium berghei EXP-1 interacts with host Apolipoprotein H during Plasmodium liver-stage development

Identification and Characterization of the Protective Gene of homolog of Exported Protein 1

Luciferase, When Fused to an N-terminal Signal Peptide, Is Secreted from Transfected Plasmodium falciparum and Transported to the Cytosol of Infected Erythrocytes

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