Cloning and Protein Structure Prediction of DBL2β-PfEMP1 Recombinant Protein from Indonesian Plasmodium falciparum Isolate

Abstract

The DBL2β-PfEMP1 is an adhesive domain of Plasmodium falciparum, which is important for malaria pathogenesis. In this study, the DBL2βPfEMP1 from the Indonesian isolate of Plasmodium

falciparum was cloned and the protein structure prediction of the DBL2β recombinant protein as well as its ligand binding sites was carried out. The DBL2β recombinant protein consists of 1674 nucleotides which are translated into 558 amino

acids. Analysis using Expasy ProtParam tool showed

that the protein had a MW of 64.69 kDa with an

isoelectric point of 8.82. It had 83 negatively

charged residues (Asp + Glu) and 98 positively

charged residues (Arg + Lys). It was classified as

an unstable protein because it had an instability index of 40.01. Protein structure prediction of the

DBL2β recombinant protein and its binding sites

was carried out using the I-TASSER program. It

showed that the DBL2β recombinant protein had

the highest significant alignment with the DBLβ domain of PF11_0521 PfEMP1, which is bound to the human ICAM-1, but the protein had the closest structural similarity with the of EBA-175 Region II (RII) of P. falciparum, where the protein functions as the cell invasion molecule. The highest C-score of ligand-binding site was 0.10 for the PEPTIDE ligand (GLN, LEU, ASP, PHE, GLU, ASP, VAL, TRP, ASN, SER, SER, TYR), and the ligand-binding site residues were at 84, 87, 88, 91, 92, 95, 99, 196, 199, 200, 203, 206. It is likely that the DBL2β recombinant protein has the major function as an adhesion molecule for invasion to the host. Further studies on its role in in vivo models are needed to develop a definite conclusion.