title: Fine mapping of Plasmodium falciparum ribosomal phosphoprotein PfP0 revealed sequences with highly specific binding activity to human red blood cells.
abstract: The Plasmodium falciparum P0 ribosomal phosphoprotein (PfP0) was identified for the first time by screening a cDNA expression library of P. falciparum parasites with sera from malaria-immune individuals. Due to its localization on the surface of different parasite life-cycle stages (merozoites and gametocytes) and its recognition by invasion-blocking antibodies, PfP0 has been considered a potential malaria-vaccine component. In this study, 16 20-mer-long synthetic peptides spanning the entire PfP0 sequence were evaluated by means of receptor-ligand assays with human red blood cells (RBCs) in order to determine the role played by these peptides in the invasion process. Four RBC high-activity binding peptides (HABPs), located mostly toward the N-terminal region, were identified: HABP 33898 ((1)MAKLSKQQKKQMYIEKLSSL(20)), HABP 33900 ((41)ASVRKSLRGKATILMGKNTRY(60)), HABP 33901 ((61)IRTALKKNLQAVPQIEKLLPY (80)), and HABP 33906 ((161)LIKQGEKVTASSATLLRKFNY(180)). The binding pattern of HABPs 33898 and 33906 to enzyme-treated RBCs suggests receptors of protein nature for these two HABPs, one of which could correspond to a common 58-kDa RBC membrane protein, as indicated by results of cross-linking assays. Both HABPs exhibited high content of alpha-helical features and prevented P. falciparum merozoite invasion to RBCs in vitro by up to 91%. The invasion-blocking ability reported here for these PfP0 HABPs supports their inclusion in immunological studies with the aim of assessing their potential as candidates for a vaccine against P. falciparum malaria.
authors.affiliation: Fundación Instituto de Inmunología de Colombia FIDIC, Cra. 50 No 26-20, Bogotá, Colombia.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Arevalo-Pinzon
authors.forename: Hernando
authors.initials: H
authors.lastname: Curtidor
authors.forename: Claudia
authors.initials: C
authors.lastname: Reyes
authors.forename: Martha
authors.initials: M
authors.lastname: Pinto
authors.forename: Carolina
authors.initials: C
authors.lastname: Vizcaíno
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Patarroyo
authors.forename: Manuel E
authors.initials: ME
authors.lastname: Patarroyo
mesh_terms: D000595:Amino Acid Sequence; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D015800:Protozoan Proteins; D012269:Ribosomal Proteins; C054675:ribosomal protein P0