title: Mapping binding residues in the Plasmodium vivax domain that binds Duffy antigen during red cell invasion.
abstract: Summary Plasmodium vivax depends on interaction with the Duffy antigen/receptor for chemokines (DARC) for invasion of human erythrocytes. The 140 kDa P. vivax Duffy-binding protein (PvDBP) mediates interaction with DARC. The receptor-binding domain of PvDBP maps to its N-terminal, cysteine-rich region, region II (PvRII), which contains approximately 300 amino acid residues including 12 conserved cysteines. Using surface plasmon resonance, we show that binding of PvRII to DARC is a high-affinity interaction with a binding constant (K(D)) of 8.7 nM. The minimal binding domain of PvRII has been previously mapped to a central 170-amino-acid stretch that includes cysteines 5-8. Here, we have used site-directed mutagenesis and quantitative binding assays to map amino acid residues within PvRII that make contact with DARC. Of the seven alanine replacement mutations that had an effect on binding, five were mutations in hydrophobic residues suggesting that hydrophobic interactions play a major role in the interaction of PvDBP with DARC. Genetic diversity studies have shown that six of the seven binding residues identified in PvRII are conserved in P. vivax field isolates, which provides support for their role in interaction with DARC.
authors.affiliation: Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110067, India.
authors.forename: Dhiraj
authors.initials: D
authors.lastname: Hans
authors.forename: Priyabrata
authors.initials: P
authors.lastname: Pattnaik
authors.forename: Arindam
authors.initials: A
authors.lastname: Bhattacharyya
authors.forename: Ahmad Rushdi
authors.initials: AR
authors.lastname: Shakri
authors.forename: Syed Shams
authors.initials: SS
authors.lastname: Yazdani
authors.forename: Monal
authors.initials: M
authors.lastname: Sharma
authors.forename: Hyeryun
authors.initials: H
authors.lastname: Choe
authors.forename: Michael
authors.initials: M
authors.lastname: Farzan
authors.forename: Chetan E
authors.initials: CE
authors.lastname: Chitnis
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000378:metabolism; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D018925:Chemokines / Q000378:metabolism*; D004375:Duffy Blood-Group System / Q000378:metabolism*; D010966:Plasmodium vivax / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: C473745:ACKR1 protein, human; D000953:Antigens, Protozoan; D002352:Carrier Proteins; D018925:Chemokines; D004375:Duffy Blood-Group System; C066001:Duffy antigen binding protein, Plasmodium; D015800:Protozoan Proteins; D011956:Receptors, Cell Surface