Akansha Pant
National Institute of Malaria Research, New Delhi, India
Title: Disruption of falcipains processing by blocking hotspot spot residues of domains in Malaria parasite
Biography
Biography: Akansha Pant
Abstract
Falcipains are among the critical enzymes required for parasite machinery in Malaria. Our previous study suggested that they have unique pro and mature domains that interact via salt bridge and hydrophobic interactions, which are essential for their activation. Designing small molecules that interfere at the hotspot residues of domains, would inhibit falcipains activation. Although multiple active site inhibitors exist for falcipains, specific inhibitors that halt processing without binding to active site remains unknown. Our study suggests that azapeptide compounds based on conformationally constrained disubstituted β- and γ-amino acids, inhibit the activation of falcipains. Among these, C-02 and C-07 hinders the falcipains activity by binding to intact pro-FP2 rather than mature active FP2 during hemoglobin hydrolysis and fluorogenic substrate assay. While these compounds did not affect the secondary structure of protein during circular dichroism spectroscopy, Surface Plasmon Resonance result demonstrated over the range of inhibitor concentration indicated specific interaction with FP3 and equilibrium constant~80nM. Moreover confirmation was done by MD simulations for ~5x130 ns confirms that compound-inhibitor complex provides rigidity to the pro domain to remain intact even at low pH preventing activation of the enzyme. For further authentication inhibitory concentration (IC50), of compound were examined on 3D7 strain of Plasmodium falciparum, parasite shows distorted trophozoite morphology with IC50~250nM. Further, we report a conserved histidine residue (His205) in pro domain of FP3, essential for pH sensing during auto-processing. Collectively, we provide a framework for targeting hotspot residues that can regulate falcipains in zymogen condition and halts its activation.