title: Identification of a Plasmodium falciparum inhibitor-2 motif involved in the binding and regulation activity of protein phosphatase type 1.
abstract: The regulation of Plasmodium falciparum protein phosphatase type 1 (PfPP1) activity remains to be deciphered. Data from homologous eukaryotic type 1 protein phosphatases (PP1) suggest that several protein regulators should be involved in this essential process. One such regulator, named PfI2 based on its primary sequence homology with eukaryotic inhibitor 2 (I2), was recently shown to be able to interact with PfPP1 and to inhibit its phosphatase activity, mainly through the canonical 'RVxF' binding motif. The details of the structural and functional characteristics of this interaction are investigated here. Using NMR spectroscopy, a second site of interaction is suggested to reside between residues D94 and T117 and contains the 'FxxR/KxR/K' binding motif present in other I2 proteins. This site seems to play in concert/synergy with the 'RVxF' motif to bind PP1, because only mutations in both motifs were able to abolish this interaction completely. However, regarding the structure/function relationship, mutation of either the 'RVxF' or 'FxxR/KxR/K' motif is more drastic, because each mutation prevents the capacity of PfI2 to trigger germinal vesicle breakdown in microinjected Xenopus oocytes. This indicates that the tight association of the PfI2 regulator to PP1, mediated by a two-site interaction, is necessary to exert its function. Based on these results, the use of a peptide derived from the 'FxxR/KxR/K' PfI2 motif was investigated for its potential effect on Plasmodium growth. This peptide, fused at its N-terminus to a penetrating sequence, was shown to accumulate specifically in infected erythrocytes and to have an antiplasmodial effect.
authors.affiliation: Center for Infection and Immunity of Lille, Inserm U1019-CNRS UMR 8204, Université Lille Nord de France, Institut Pasteur de Lille, France.
authors.forename: Aline
authors.initials: A
authors.lastname: Fréville
authors.forename: Géraldine
authors.initials: G
authors.lastname: Tellier
authors.forename: Audrey
authors.initials: A
authors.lastname: Vandomme
authors.forename: Christine
authors.initials: C
authors.lastname: Pierrot
authors.forename: Jérôme
authors.initials: J
authors.lastname: Vicogne
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Cantrelle
authors.forename: Alain
authors.initials: A
authors.lastname: Martoriati
authors.forename: Katia
authors.initials: K
authors.lastname: Cailliau-Maggio
authors.forename: Jamal
authors.initials: J
authors.lastname: Khalife
authors.forename: Isabelle
authors.initials: I
authors.lastname: Landrieu
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D000962:Antimalarials / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D002478:Cells, Cultured; D004353:Drug Evaluation, Preclinical; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D004912:Erythrocytes / Q000469:parasitology; D006801:Humans; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000187:drug effects / Q000201:enzymology*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D054645:Protein Phosphatase 1 / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000502:physiology; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000502:physiology; D014982:Xenopus laevis
chemical_list: D000962:Antimalarials; D004791:Enzyme Inhibitors; D015800:Protozoan Proteins; D054645:Protein Phosphatase 1
keywords: NMR spectroscopy; PP1 inhibitor 2; Plasmodium falciparum; protein phosphatase type 1; protein-protein interaction