Limits...
The cytoplasmic domain of the Plasmodium falciparum ligand EBA-175 is essential for invasion but not protein trafficking.

Gilberger TW, Thompson JK, Reed MB, Good RT, Cowman AF - J. Cell Biol. (2003)

Bottom Line: The invasion of host cells by the malaria parasite Plasmodium falciparum requires specific protein-protein interactions between parasite and host receptors and an intracellular translocation machinery to power the process.In this report, we show that the cytoplasmic domain of EBA-175 encodes crucial information for its role in merozoite invasion, and that trafficking of this protein is independent of this domain.These results show that the parasite uses the same components of its cellular machinery for invasion regardless of the host cell type and invasive form.

View Article: PubMed Central - PubMed

Affiliation: The Walter and Eliza Hall Institute of Medical Research, Melbourne 3050, Australia.

ABSTRACT
The invasion of host cells by the malaria parasite Plasmodium falciparum requires specific protein-protein interactions between parasite and host receptors and an intracellular translocation machinery to power the process. The transmembrane erythrocyte binding protein-175 (EBA-175) and thrombospondin-related anonymous protein (TRAP) play central roles in this process. EBA-175 binds to glycophorin A on human erythrocytes during the invasion process, linking the parasite to the surface of the host cell. In this report, we show that the cytoplasmic domain of EBA-175 encodes crucial information for its role in merozoite invasion, and that trafficking of this protein is independent of this domain. Further, we show that the cytoplasmic domain of TRAP, a protein that is not expressed in merozoites but is essential for invasion of liver cells by the sporozoite stage, can substitute for the cytoplasmic domain of EBA-175. These results show that the parasite uses the same components of its cellular machinery for invasion regardless of the host cell type and invasive form.

Show MeSH

Related in: MedlinePlus

A proposed model of trafficking and function for EBA-175. (A) Schematic representation of a merozoite. Secretory proteins enter the lumen of the endoplasmic reticulum (ER) with their NH2-terminal signal peptide. The molecular mechanism of pre- and post-Golgi trafficking (TGN) and the differential sorting of microneme (MIC) and rhoptry (R) proteins to their final destination is unclear. (B) In a post-Golgi sorting event, EBA-175 is trafficked to the micronemes by an escorter protein. The protein–protein interaction may take place via the conserved 3′ cysteine-rich region. The information of neither microneme localization nor interaction with the escorter protein is encrypted in the cytoplasmic domain of EBA-175. Deletion of the cytoplasmic domain does not affect sorting to the micronemes. Sorting was disrupted by deletion of the transmembrane domain and the 3′ cysteine rich region. (C) The intracellular function of EBA-175 is dependent on the interaction of an adaptor protein with the cytoplasmic domain. The deletion of this region abolishes the binding of the adaptor protein and leads to disruption of its function. The cytoplasmic domain can be substituted by the cytoplasmic domain of the sporozoite protein TRAP, suggesting that EBA-175 and TRAP have functionally equivalent roles in the active invasion process.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2172798&req=5

fig6: A proposed model of trafficking and function for EBA-175. (A) Schematic representation of a merozoite. Secretory proteins enter the lumen of the endoplasmic reticulum (ER) with their NH2-terminal signal peptide. The molecular mechanism of pre- and post-Golgi trafficking (TGN) and the differential sorting of microneme (MIC) and rhoptry (R) proteins to their final destination is unclear. (B) In a post-Golgi sorting event, EBA-175 is trafficked to the micronemes by an escorter protein. The protein–protein interaction may take place via the conserved 3′ cysteine-rich region. The information of neither microneme localization nor interaction with the escorter protein is encrypted in the cytoplasmic domain of EBA-175. Deletion of the cytoplasmic domain does not affect sorting to the micronemes. Sorting was disrupted by deletion of the transmembrane domain and the 3′ cysteine rich region. (C) The intracellular function of EBA-175 is dependent on the interaction of an adaptor protein with the cytoplasmic domain. The deletion of this region abolishes the binding of the adaptor protein and leads to disruption of its function. The cytoplasmic domain can be substituted by the cytoplasmic domain of the sporozoite protein TRAP, suggesting that EBA-175 and TRAP have functionally equivalent roles in the active invasion process.

Mentions: The results presented here suggest a model for trafficking of EBA-175 that involves an escorter protein specifying the targeting information required for microneme localization (Fig. 6, A and B). We presume that EBA-175 and other microneme proteins are processed through the classical secretory pathway involving the ER and Golgi followed by unknown sorting machinery in the TGN (Fig. 6 A). The trafficking of EBA-175 to the micronemes is independent of the cytoplasmic domain, and we propose that an escorter protein forming a complex is required for this specific sorting event (Fig. 6 B). The inability of EBA-175Δ230 protein to be trafficked to the micronemes suggests that the cysteine-rich region and/or the transmembrane domain are involved in complex formation. It is likely that the 3′ cysteine-rich region is important in protein sorting, as it is conserved in other paralogues that function in merozoite invasion, and it is likely that these proteins are sorted and localized to the micronemes by identical mechanisms.


The cytoplasmic domain of the Plasmodium falciparum ligand EBA-175 is essential for invasion but not protein trafficking.

Gilberger TW, Thompson JK, Reed MB, Good RT, Cowman AF - J. Cell Biol. (2003)

A proposed model of trafficking and function for EBA-175. (A) Schematic representation of a merozoite. Secretory proteins enter the lumen of the endoplasmic reticulum (ER) with their NH2-terminal signal peptide. The molecular mechanism of pre- and post-Golgi trafficking (TGN) and the differential sorting of microneme (MIC) and rhoptry (R) proteins to their final destination is unclear. (B) In a post-Golgi sorting event, EBA-175 is trafficked to the micronemes by an escorter protein. The protein–protein interaction may take place via the conserved 3′ cysteine-rich region. The information of neither microneme localization nor interaction with the escorter protein is encrypted in the cytoplasmic domain of EBA-175. Deletion of the cytoplasmic domain does not affect sorting to the micronemes. Sorting was disrupted by deletion of the transmembrane domain and the 3′ cysteine rich region. (C) The intracellular function of EBA-175 is dependent on the interaction of an adaptor protein with the cytoplasmic domain. The deletion of this region abolishes the binding of the adaptor protein and leads to disruption of its function. The cytoplasmic domain can be substituted by the cytoplasmic domain of the sporozoite protein TRAP, suggesting that EBA-175 and TRAP have functionally equivalent roles in the active invasion process.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172798&req=5

fig6: A proposed model of trafficking and function for EBA-175. (A) Schematic representation of a merozoite. Secretory proteins enter the lumen of the endoplasmic reticulum (ER) with their NH2-terminal signal peptide. The molecular mechanism of pre- and post-Golgi trafficking (TGN) and the differential sorting of microneme (MIC) and rhoptry (R) proteins to their final destination is unclear. (B) In a post-Golgi sorting event, EBA-175 is trafficked to the micronemes by an escorter protein. The protein–protein interaction may take place via the conserved 3′ cysteine-rich region. The information of neither microneme localization nor interaction with the escorter protein is encrypted in the cytoplasmic domain of EBA-175. Deletion of the cytoplasmic domain does not affect sorting to the micronemes. Sorting was disrupted by deletion of the transmembrane domain and the 3′ cysteine rich region. (C) The intracellular function of EBA-175 is dependent on the interaction of an adaptor protein with the cytoplasmic domain. The deletion of this region abolishes the binding of the adaptor protein and leads to disruption of its function. The cytoplasmic domain can be substituted by the cytoplasmic domain of the sporozoite protein TRAP, suggesting that EBA-175 and TRAP have functionally equivalent roles in the active invasion process.
Mentions: The results presented here suggest a model for trafficking of EBA-175 that involves an escorter protein specifying the targeting information required for microneme localization (Fig. 6, A and B). We presume that EBA-175 and other microneme proteins are processed through the classical secretory pathway involving the ER and Golgi followed by unknown sorting machinery in the TGN (Fig. 6 A). The trafficking of EBA-175 to the micronemes is independent of the cytoplasmic domain, and we propose that an escorter protein forming a complex is required for this specific sorting event (Fig. 6 B). The inability of EBA-175Δ230 protein to be trafficked to the micronemes suggests that the cysteine-rich region and/or the transmembrane domain are involved in complex formation. It is likely that the 3′ cysteine-rich region is important in protein sorting, as it is conserved in other paralogues that function in merozoite invasion, and it is likely that these proteins are sorted and localized to the micronemes by identical mechanisms.

Bottom Line: The invasion of host cells by the malaria parasite Plasmodium falciparum requires specific protein-protein interactions between parasite and host receptors and an intracellular translocation machinery to power the process.In this report, we show that the cytoplasmic domain of EBA-175 encodes crucial information for its role in merozoite invasion, and that trafficking of this protein is independent of this domain.These results show that the parasite uses the same components of its cellular machinery for invasion regardless of the host cell type and invasive form.

View Article: PubMed Central - PubMed

Affiliation: The Walter and Eliza Hall Institute of Medical Research, Melbourne 3050, Australia.

ABSTRACT
The invasion of host cells by the malaria parasite Plasmodium falciparum requires specific protein-protein interactions between parasite and host receptors and an intracellular translocation machinery to power the process. The transmembrane erythrocyte binding protein-175 (EBA-175) and thrombospondin-related anonymous protein (TRAP) play central roles in this process. EBA-175 binds to glycophorin A on human erythrocytes during the invasion process, linking the parasite to the surface of the host cell. In this report, we show that the cytoplasmic domain of EBA-175 encodes crucial information for its role in merozoite invasion, and that trafficking of this protein is independent of this domain. Further, we show that the cytoplasmic domain of TRAP, a protein that is not expressed in merozoites but is essential for invasion of liver cells by the sporozoite stage, can substitute for the cytoplasmic domain of EBA-175. These results show that the parasite uses the same components of its cellular machinery for invasion regardless of the host cell type and invasive form.

Show MeSH
Related in: MedlinePlus