title: Plasmodium falciparum: binding studies of peptide derived from the sporozoite surface protein 2 to Hep G2 cells.
abstract: Plasmodium falciparum sporozoite surface protein 2 (Pf SSP2), also called thrombospondin related anonymous protein (TRAP), is involved in the process of sporozoite invasion of hepatocytes. Pf SSP2/TRAP possesses two different adhesion domains sharing sequences and structural homology with von Willebrand factor A-domains and human repeat I thrombospondin (TSP). Pf SSP2/TRAP has also been implicated in sporozoite mobility and in mosquito salivary gland invasion processes. We tested 15-mer long synthetic peptides having five overlapping residues covering the complete protein Pf SSP2 sequence in binding assays to Hep G2 cells. In these 57 peptides, 21 high-activity binding peptides (HABPs) were identified; five were in the adhesion domains already described and 16 were in two regions toward the protein's carboxy and middle terminal part. Six HABPs showed conserved amino acid sequences: 3243 (21FLVNGRDVQNNIVDE35), 3279 (201FLVGCHPSDGKCNLY215), 3287 (241TASCGVWDEWSPCSV255), 3289 (251SPCSVTCGKGTRSRK265), 3327 (441ERKQSDPQSQDNNGNY455) and 3329 (451DNNGNRHVPNSEDREY465). The HABPs show saturable binding and dissociation constants between 140 and 900 nm with 40 000-855 000 binding sites per cell. The 3279 (201FLVGCHPSDGKCNLY215), 3323 (421NDKSDRYIPYSPLSP435) and 3331 (461SEDRETRPHGRNNENY475) HABPs have B epitopes in their sequences; these have previously been recognized by antibodies partially inhibiting hepatocyte invasion and development of the hepatic state. The 3287 (241TASCGVWDEWSPCSV255) and 3289 (251SPCSVTCGKGTRSRK265) HABPs share common sequences with the Pf SSP2/TRAP region II plus, which is present in a great number of adhesion proteins. Based on this information, six new peptides covering the high binding regions identified previously were synthesized and, using a competition assay, the amino acid involved in the binding were determined.
authors.affiliation: Instituto de Inmunología, Hospital San Juan de Dios, Universidad Nacional de Colombia, Avda. Calle 26 No. 51-60 Bogotá, Colombia. ramseslopez@hotmail.com
authors.forename: R
authors.initials: R
authors.lastname: López
authors.forename: H
authors.initials: H
authors.lastname: Curtidor
authors.forename: M
authors.initials: M
authors.lastname: Urquiza
authors.forename: J
authors.initials: J
authors.lastname: Garcia
authors.forename: A
authors.initials: A
authors.lastname: Puentes
authors.forename: J
authors.initials: J
authors.lastname: Suarez
authors.forename: M
authors.initials: M
authors.lastname: Ocampo
authors.forename: R
authors.initials: R
authors.lastname: Vera
authors.forename: L E
authors.initials: LE
authors.lastname: Rodriguez
authors.forename: F
authors.initials: F
authors.lastname: Castillo
authors.forename: G
authors.initials: G
authors.lastname: Cifuentes
authors.forename: M E
authors.initials: ME
authors.lastname: Patarroyo
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000378:metabolism*; D017124:Conserved Sequence / Q000235:genetics; D006801:Humans; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D010963:Plasmodium falciparum; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism*; D017385:Sequence Homology; D014407:Tumor Cells, Cultured / Q000378:metabolism; D014841:von Willebrand Factor / Q000235:genetics
chemical_list: D015815:Cell Adhesion Molecules; D010455:Peptides; D015800:Protozoan Proteins; D014841:von Willebrand Factor; C069428:thrombospondin-related adhesive protein, protozoan