Essential role of GEXP15, a specific Protein Phosphatase type 1 partner, in Plasmodium berghei in asexual erythrocytic proliferation and transmission

• Published in: PLoS pathogens 2019-07, Vol.15 (7), p.e1007973-e1007973
• Main Authors: Hollin, Thomas, De Witte, Caroline, Fréville, Aline, Guerrera, Ida Chiara, Chhuon, Cerina, Saliou, Jean-Michel, Herbert, Fabien, Pierrot, Christine, Khalife, Jamal
• Format: Article
• Language: English
• Subjects: Animals; Anopheles - parasitology; Aquatic insects; Binding sites; Biochemistry, Molecular Biology; Biology and Life Sciences; Blood parasites; Catalysis; Cell cycle; Control; Cost analysis; Depletion; Disease transmission; Erythrocytes; Erythrocytes - parasitology; Eukaryotes; Exports; Female; Fitness; Gametocytes; Gene expression; Genes; Genes, Protozoan; Genetic aspects; Host-Parasite Interactions - genetics; Host-Parasite Interactions - physiology; House mouse; Humans; Immunoprecipitation; Infections; Kinases; Life cycles; Life cycles (Biology); Life Sciences; Malaria; Malaria - parasitology; Malaria - transmission; Male; Mass spectrometry; Mass spectroscopy; Medicine and Health Sciences; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Microbiology and Parasitology; Mosquito Vectors - parasitology; Mutation; Oocysts; Parasites; Peptides; Phosphatase; Phosphatases; Phosphorylation; Plasmodium; Plasmodium berghei - genetics; Plasmodium berghei - growth & development; Plasmodium berghei - physiology; Proteasomes; Protein Binding; Protein Interaction Domains and Motifs; Protein phosphatase; Protein Phosphatase 1 - chemistry; Protein Phosphatase 1 - genetics; Protein Phosphatase 1 - physiology; Proteins; Proteomics; Protozoan Proteins - chemistry; Protozoan Proteins - genetics; Protozoan Proteins - physiology; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Reproductive fitness; Research and Analysis Methods; Risk factors; Schizonts; Sexuality; Spectroscopy; Sporozoites; Vector-borne diseases; Virulence
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1007973

The essential and distinct functions of Protein Phosphatase type 1 (PP1) catalytic subunit in eukaryotes are exclusively achieved through its interaction with a myriad of regulatory partners. In this work, we report the molecular and functional characterization of Gametocyte EXported Protein 15 (GEXP15), a Plasmodium specific protein, as a regulator of PP1. In vitro interaction studies demonstrated that GEXP15 physically interacts with PP1 through the RVxF binding motif in P. berghei. Functional assays showed that GEXP15 was able to increase PP1 activity and the mutation of the RVxF motif completely abolished this regulation. Immunoprecipitation assays of tagged GEXP15 or PP1 in P. berghei followed by immunoblot or mass spectrometry analyses confirmed their interaction and showed that they are present both in schizont and gametocyte stages in shared protein complexes involved in the spliceosome and proteasome pathways and known to play essential role in parasite development. Phenotypic analysis of viable GEXP15 deficient P. berghei blood parasites showed that they were unable to develop lethal infection in BALB/c mice or to establish experimental cerebral malaria in C57BL/6 mice. Further, although deficient parasites produced gametocytes they did not produce any oocysts/sporozoites indicating a high fitness cost in the mosquito. Global proteomic and phosphoproteomic analyses of GEXP15 deficient schizonts revealed a profound defect with a significant decrease in the abundance and an impact on phosphorylation status of proteins involved in regulation of gene expression or invasion. Moreover, depletion of GEXP15 seemed to impact mainly the abundance of some specific proteins of female gametocytes. Our study provides the first insight into the contribution of a PP1 regulator to Plasmodium virulence and suggests that GEXP15 affects both the asexual and sexual life cycle.