title: Characterisation of Plasmodium falciparum RESA-like protein peptides that bind specifically to erythrocytes and inhibit invasion.
abstract: The Plasmodium falciparum ring-erythrocyte surface antigen (RESA)-like putative protein was identified and characterised. PCR and RT-PCR assays revealed that the gene encoding this protein was both present and being transcribed in P. falciparum strain FCB-2 16 h after erythrocyte invasion. Indirect immunofluorescence studies detected this protein in infected erythrocyte (IE) cytosol in dense fluorescent granules similar to Maurer's clefts at 16-20 h (parasites in ring and trophozoite stages) and very strongly on IE membranes at 22 h, suggesting that it is synthesised during early ring stages (16 h) and transported to the infected red blood cell (RBC) membrane surface during the trophozoite stage (22 h). Western blotting showed that antisera produced against polymerised synthetic peptides of this protein recognised a 72-kDa band in P. falciparum schizont lysate. P. falciparum RESA-like peptides used in normal RBC binding assays revealed that peptides 30326 ((101)NAEKI LGFDD KNILE ALDLFY(120)), 30334 ((281)RVTWK KLRTK MIKAL KKSLTY(300)) and 30342 ((431)SSPQR LKFTA GGGFC GKLRNY(450)) bind with high activity and saturability, presenting nM affinity constants. These peptides contain alpha-helical structural elements, as determined by circular dichroism, and inhibit P. falciparum in vitro invasion of normal RBCs by up to 91%, suggesting that some RESA-like protein regions are involved in intra-erythrocyte stage P. falciparum invasion.
authors.affiliation: Fundación Instituto de Inmunologia de Colombia and Universidad Nacional de Colombia, Carrera 50 No. 26-00, Bogotá, Colombia.
authors.forename: Luis Eduardo
authors.initials: LE
authors.lastname: Rodriguez
authors.forename: Ricardo
authors.initials: R
authors.lastname: Vera
authors.forename: John
authors.initials: J
authors.lastname: Valbuena
authors.forename: Hernando
authors.initials: H
authors.lastname: Curtidor
authors.forename: Javier
authors.initials: J
authors.lastname: Garcia
authors.forename: Alvaro
authors.initials: A
authors.lastname: Puentes
authors.forename: Marisol
authors.initials: M
authors.lastname: Ocampo
authors.forename: Ramses
authors.initials: R
authors.lastname: Lopez
authors.forename: Jaiver
authors.initials: J
authors.lastname: Rosas
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Lopez
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; D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000954:Antigens, Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002918:Chymotrypsin / Q000378:metabolism; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000378:metabolism* / Q000469:parasitology; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D052940:Merozoites / Q000187:drug effects / Q000254:growth & development; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism* / Q000494:pharmacology; D010963:Plasmodium falciparum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D014158:Transcription, Genetic; D014357:Trypsin / Q000378:metabolism
chemical_list: D000953:Antigens, Protozoan; D000954:Antigens, Surface; D010455:Peptides; D002918:Chymotrypsin; D014357:Trypsin