Structure of the malaria vaccine candidate antigen CyRPA and its complex with a parasite invasion inhibitory antibody
Abstract
Invasion of erythrocytes by Plasmodial merozoites is a composite process involving the interplay of several proteins. Among them, the Plasmodium falciparum Cysteine-Rich Protective Antigen (PfCyRPA) is a crucial component of a ternary complex, including Reticulocyte binding-like Homologous protein 5 (PfRH5) and the RH5-interacting protein (PfRipr), essential for erythrocyte invasion. Here we present the crystal structure of PfCyRPA and of its complex with the antigen-binding fragment of a parasite growth inhibitory antibody. While PfCyRPA adopts a 6-bladed β-propeller structure with similarity to the classic sialidase fold, it possesses no sialidase activity, indicating that it fulfills a non-enzymatic function. Characterization of the epitope recognized by protective antibodies will facilitate design of peptidomimetics that focus vaccine responses on protective epitopes. Both in vitro and in vivo anti-PfCyRPA and anti-PfRH5 antibodies showed more potent parasite growth inhibitory activity in combination than on their own, supporting a combined delivery of PfCyRPA and PfRH5 in vaccines.
Data availability
-
Crystal Structure of Fab c12Publicly available at the RCSB Protein Data Bank (accession no: 5EZI).
-
Crystal Structure of Fab c12Publicly available at the RCSB Protein Data Bank (accession no: 5EZL).
-
Crystal Structure of Fab c12Publicly available at the RCSB Protein Data Bank (accession no: 5EZJ).
-
Crystal Structure of PfCyRPAPublicly available at the RCSB Protein Data Bank (accession no: 5EZN).
-
Crystal Structure of PfCyRPAPublicly available at the RCSB Protein Data Bank (accession no: 5EZO).
-
PlasmoDB: a functional genomic database for malaria parasites.The data at this site is provided freely for public use.
Article and author information
Author details
Funding
Uniscientia Stiftung
- Gerd Pluschke
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Stephen C. Harrison, Harvard Medical School, United States
Ethics
Animal experimentation: All procedures involving living animals were performed in strict accordance with the Rules and Regulations for the Protection of Animal Rights (Tierschutzverordnung) of the Swiss Federal Food Safety and Veterinary Office. The protocol was granted ethical approval by the Veterinary Office of the county of Basel-Stadt, Switzerland (Permit Numbers: 2375 and 2303).
Version history
- Received: August 8, 2016
- Accepted: February 6, 2017
- Accepted Manuscript published: February 14, 2017 (version 1)
- Version of Record published: March 14, 2017 (version 2)
Copyright
© 2017, Favuzza et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 3,027
- views
-
- 617
- downloads
-
- 50
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Further reading
-
- Structural Biology and Molecular Biophysics
Roco proteins entered the limelight after mutations in human LRRK2 were identified as a major cause of familial Parkinson’s disease. LRRK2 is a large and complex protein combining a GTPase and protein kinase activity, and disease mutations increase the kinase activity, while presumably decreasing the GTPase activity. Although a cross-communication between both catalytic activities has been suggested, the underlying mechanisms and the regulatory role of the GTPase domain remain unknown. Several structures of LRRK2 have been reported, but structures of Roco proteins in their activated GTP-bound state are lacking. Here, we use single-particle cryo-electron microscopy to solve the structure of a bacterial Roco protein (CtRoco) in its GTP-bound state, aided by two conformation-specific nanobodies: NbRoco1 and NbRoco2. This structure presents CtRoco in an active monomeric state, featuring a very large GTP-induced conformational change using the LRR-Roc linker as a hinge. Furthermore, this structure shows how NbRoco1 and NbRoco2 collaborate to activate CtRoco in an allosteric way. Altogether, our data provide important new insights into the activation mechanism of Roco proteins, with relevance to LRRK2 regulation, and suggest new routes for the allosteric modulation of their GTPase activity.
-
- Developmental Biology
- Structural Biology and Molecular Biophysics
A crucial event in sexual reproduction is when haploid sperm and egg fuse to form a new diploid organism at fertilization. In mammals, direct interaction between egg JUNO and sperm IZUMO1 mediates gamete membrane adhesion, yet their role in fusion remains enigmatic. We used AlphaFold to predict the structure of other extracellular proteins essential for fertilization to determine if they could form a complex that may mediate fusion. We first identified TMEM81, whose gene is expressed by mouse and human spermatids, as a protein having structural homologies with both IZUMO1 and another sperm molecule essential for gamete fusion, SPACA6. Using a set of proteins known to be important for fertilization and TMEM81, we then systematically searched for predicted binary interactions using an unguided approach and identified a pentameric complex involving sperm IZUMO1, SPACA6, TMEM81 and egg JUNO, CD9. This complex is structurally consistent with both the expected topology on opposing gamete membranes and the location of predicted N-glycans not modeled by AlphaFold-Multimer, suggesting that its components could organize into a synapse-like assembly at the point of fusion. Finally, the structural modeling approach described here could be more generally useful to gain insights into transient protein complexes difficult to detect experimentally.