L-Asparaginase of Leishmania donovani: Metabolic target and its role in Amphotericin B resistance

Abstract

Emergence of Amphotericin B (AmB) resistant Leishmania donovani has posed major therapeutic challenge against the parasite. Consequently, combination therapy aimed at multiple molecular targets, based on proteome wise network analysis has been recommended. In this regard we had earlier identified and proposed L-asparaginase of Leishmania donovani (LdAI) as a crucial metabolic target. Here we report that both LdAI overexpressing axenic amastigote and promastigote forms of L. donovani survives better when challenged with AmB as compared to wild type strain. Conversely, qRT-PCR analysis showed an upregulation of LdAI in both forms upon AmB treatment. Our data demonstrates the importance of LdAI in imparting immediate protective response to the parasite upon AmB treatment. In the absence of structural and functional information, we modeled LdAI and validated its solution structure through small angle X-ray scattering (SAXS) analysis. We identified its specific inhibitors through ligand and structure-based approach and characterized their effects on enzymatic properties (Km, Vmax, Kcat) of LdAI. We show that in presence of two of the inhibitors L1 and L2, the survival of L. donovani is compromised whereas overexpression of LdAI in these cells restores viability. Taken together, our results conclusively prove that LdAI is a crucial metabolic enzyme conferring early counter measure against AmB treatment by Leishmania.

Identification of trans-2-cis-8-Matricaria-ester from the Essential Oil of Erigeron multiradiatus and Evaluation of Its Antileishmanial Potential by in Vitro and in Silico Approaches

“…33 DNA topoisomerases are the key enzymes that facilitate high precision DNA transactions inside the parasite, 34 and l -asparginases are associated with the survival of the parasite. 35 The major EO component, trans -2- cis -8-matricaria ester represents a good inhibitory effect on the four major essential parasite proteins with nontoxic properties. So these enzymes could be used as a potential drug target against the pathogen Leishmania .…”

SARS-CoV-2 ORF8 can fold into human factor 1 catalytic domain binding site on complement C3b: Predict functional mimicry

“…Ionic concentrations was kept at 0.1 M NaCl followed by system minimization by Steepest descent protocol. Equilibration and production runs (25 ns) were carried using parameters detailed in our previous reports [22,23]. Images were constructed using PyMol while data was analysed using standard gromacs tools.…”

Slow pace of antileishmanial drug development

“…Particular enzymes which are present in the parasite and absent from mammalian cells are of great interest. However, still, mammalian enzymes, which have structural homology, might also provide objectives for antileishmanial therapy because report showed favorable interactions of inhibitors with the active pocket of parasite enzyme, without adversely affecting human enzyme (Singh et al 2017) and this is the rationale of the listed potential target in Leishmania . They could be interesting and promising for future antileishmanial drug development.…”

“…The presence of genes coding for putative l-asparaginase enzymes in the L. donovani genome has given a hin towards the specific role of this enzyme in the survival of the parasite. Singh et al (2017) have advocated that L-asparaginases could be a potential drug target against the pathogen Leishmania .…”