title: Extensive differential protein phosphorylation as intraerythrocytic Plasmodium falciparum schizonts develop into extracellular invasive merozoites.
abstract: Pathology of the most lethal form of malaria is caused by Plasmodium falciparum asexual blood stages and initiated by merozoite invasion of erythrocytes. We present a phosphoproteome analysis of extracellular merozoites revealing 1765 unique phosphorylation sites including 785 sites not previously detected in schizonts. All MS data have been deposited in the ProteomeXchange with identifier PXD001684 (http://proteomecentral.proteomexchange.org/dataset/PXD001684). The observed differential phosphorylation between extra and intraerythrocytic life-cycle stages was confirmed using both phospho-site and phospho-motif specific antibodies and is consistent with the core motif [K/R]xx[pS/pT] being highly represented in merozoite phosphoproteins. Comparative bioinformatic analyses highlighted protein sets and pathways with established roles in invasion. Within the merozoite phosphoprotein interaction network a subnetwork of 119 proteins with potential roles in cellular movement and invasion was identified and suggested that it is coregulated by a further small subnetwork of protein kinase A (PKA), two calcium-dependent protein kinases (CDPKs), a phosphatidyl inositol kinase (PI3K), and a GCN2-like elF2-kinase with a predicted role in translational arrest and associated changes in the ubquitinome. To test this notion experimentally, we examined the overall ubiquitination level in intracellular schizonts versus extracellular merozoites and found it highly upregulated in merozoites. We propose that alterations in the phosphoproteome and ubiquitinome reflect a starvation-induced translational arrest as intracellular schizonts transform into extracellular merozoites.
authors.affiliation: School of Biomedical and Healthcare Sciences, Plymouth University, Drake Circus, Plymouth, Devon, UK.
authors.forename: Edwin
authors.initials: E
authors.lastname: Lasonder
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, UK.
authors.forename: Judith L
authors.initials: JL
authors.lastname: Green
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, UK.
authors.forename: Munira
authors.initials: M
authors.lastname: Grainger
authors.affiliation: Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, Faculté de Médicine, Université Paris Descartes - Sorbonne Paris Cité, France.|Inserm U1016, CNRS UMR8104, Institut Cochin, Paris, France.
authors.forename: Gordon
authors.initials: G
authors.lastname: Langsley
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, UK.
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Holder
mesh_terms: D004912:Erythrocytes / Q000469:parasitology*; D005110:Extracellular Space / Q000469:parasitology; D006790:Host-Parasite Interactions; D006801:Humans; D052940:Merozoites / Q000254:growth & development / Q000378:metabolism*; D010766:Phosphorylation; D010963:Plasmodium falciparum / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D020543:Proteome / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism*; D052939:Schizonts / Q000254:growth & development / Q000378:metabolism*
chemical_list: D020543:Proteome; D015800:Protozoan Proteins
keywords: Biomedicine; Malaria; P. falciparum merozoites; Phospho-motifs; Phosphoproteome