3 research outputs found
Resistance to the antimicrobial agent fosmidomycin and an FR900098 prodrug through mutations in the deoxyxylulose phosphate reductoisomerase gene (dxr)
There is a pressing need for new antimicrobial therapies to combat globally important drug-resistant human pathogens, including Plasmodium falciparum malarial parasites, Mycobacterium tuberculosis, and Gram-negative bacteria, including Escherichia coli. These organisms all possess the essential methylerythritol phosphate (MEP) pathway of isoprenoid biosynthesis, which is not found in humans. The first dedicated enzyme of the MEP pathway, 1-deoxy-d-xylulose 5-phosphate reductoisomerase (Dxr), is inhibited by the phosphonic acid antibiotic fosmidomycin and its analogs, including the N-acetyl analog FR900098 and the phosphoryl analog fosfoxacin. In order to identify mutations in dxr that confer resistance to these drugs, a library of E. coli dxr mutants was screened at lethal fosmidomycin doses. The most resistant allele (with the S222T mutation) alters the fosmidomycin-binding site of Dxr. The expression of this resistant allele increases bacterial resistance to fosmidomycin and other fosmidomycin analogs by 10-fold. These observations confirm that the primary cellular target of fosmidomycin is Dxr. Furthermore, cell lines expressing Dxr-S222T will be a powerful tool to confirm the mechanisms of action of future fosmidomycin analogs
<i>Plasmodium</i> IspD (2-C-Methyl‑d‑erythritol 4‑Phosphate Cytidyltransferase), an Essential and Druggable Antimalarial Target
As
resistance to current therapies spreads, novel antimalarials are urgently
needed. In this work, we examine the potential for therapeutic intervention
via the targeting of <i>Plasmodium</i> IspD (2-C-methyl-d-erythritol 4-phosphate cytidyltransferase), the second dedicated
enzyme of the essential methylerythritol phosphate (MEP) pathway for
isoprenoid biosynthesis. Enzymes of this pathway represent promising
therapeutic targets because the pathway is not present in humans.
The Malaria Box compound, MMV008138, inhibits <i>Plasmodium falciparum</i> growth, and PfIspD has been proposed as a candidate intracellular
target. We find that PfIspD is the sole intracellular target of MMV008138
and characterize the mode of inhibition and target-based resistance,
providing chemical validation of this target. Additionally, we find
that the <i>PfISPD</i> genetic locus is refractory to disruption
in malaria parasites, providing independent genetic validation for
efforts targeting this enzyme. This work provides compelling support
for IspD as a druggable target for the development of additional,
much-needed antimalarial agents