Plasmodium falciparum normocyte binding protein (PfNBP-1) peptides bind specifically to human erythrocytes

Plasmodium falciparum normocyte binding protein-1 (PfNBP-1), a Plasmodium vivax RBP-1 orthologue is expressed in the apical merozoite area. PfNBP-1 binds directly to human erythrocyte membrane in a sialic acid-dependent but trypsin-resistant way. Erythrocyte binding assays were done with synthetic peptides covering the sequence reported as PfNBP-1. Two specific erythrocyte high activity binding peptides were found: V-101 (F) under bar INDLDTYQY (E) under bar(Y) under bar FY (E) under bar(W) under bar(N) under barQ(120), peptide 26332, and (NTKETYLK)-N-181 (E) under bar($) under bar(L) under barN (K) under bar KKMLQNKK(200), peptide 26336. These two peptides' binding was saturable and presenting nanomolar affinity constants. The critical binding residues (those residues underlined and highlighted in bold) were determined by competition assays with glycine-scan analogue peptides. These peptides were able to block merozoite in vitro invasion of erythrocytes. (C) 2003 Elsevier Inc. All rights reserved.