Suppression of Drug Resistance Reveals a Genetic Mechanism of Metabolic Plasticity in Malaria Parasites

Abstract

Unique and essential aspects of parasite metabolism are excellent targets for development of new antimalarials. An improved understanding of parasite metabolism and drug resistance mechanisms is urgently needed. The antibiotic fosmidomycin targets the synthesis of essential isoprenoid compounds from glucose and is a candidate for antimalarial development. Our report identifies a novel mechanism of drug resistance and further describes a family of metabolic regulators in the parasite. Using a novel forward genetic approach, we also uncovered mutations that suppress drug resistance in the glycolytic enzyme PFK9. Thus, we identify an unexpected genetic mechanism of adaptation to metabolic insult that influences parasite fitness and tolerance of antimalarials.

The Metabolite Repair Enzyme Phosphoglycolate Phosphatase Regulates Central Carbon Metabolism and Fosmidomycin Sensitivity in Plasmodium falciparum

“…The roles of two other P. falciparum HAD enzymes have also recently been examined (9, 10). HAD1, the first member of this class to be functionally characterized in P.…”

“…Loss-of-function mutations in this protein lead to increased parasite resistance to fosmidomycin, and it was proposed that HAD1 has a role in negatively regulating glycolytic flux by removing glycolytic intermediates (9). Similarly, HAD2 dephosphorylates a range of glycolytic intermediates in vitro and is linked to negative regulation of glycolysis, with mutations of this enzyme leading to increased resistance to fosmidomycin (10). In contrast, PGP is a positive regulator of glycolysis by preventing the accumulation of 4-PE and subsequent inhibition of PGI by 6-phosphogluconate.…”

“…Interestingly, a second HAD enzyme, HAD2, was identified in the same screen and exhibited in vitro phosphatase activity against glycolytic intermediates, suggesting that HAD enzymes regulate multiple pathways in P. falciparum central carbon metabolism (10).…”

The 3S Enantiomer Drives Enolase Inhibitory Activity in SF2312 and Its Analogues

“…Overall, the immense therapeutic potential of the collateral lethality paradigm [4,5] highlights the utility of MethylSF2312 for studying the stereochemical demands of active site Enolase inhibition. Beyond cancer, the significance of exploiting glycolytic vulnerabilities across various infectious diseases [4,7,8,9] is supported by the initial finding on the antimicrobial effects of SF2312 under anaerobic conditions [25]: that structural differences between the Trypanosoma and human Enolase exist and may present an opportunity for selective inhibition of the former over the latter. This is further substantiated by the uptake of phosphonate compounds through the G6P shuttle present in certain microorganisms (Figure 3; note the profound effect by MethylSF2312 sensitivity with the addition of G6P, which induces expression of the G6P transporter to increase permeation of MethylSF2312).…”

“…Glycolysis is a conserved catabolic pathway [1], with a set of essential glycolysis genes and corresponding enzymes present in most organisms [2,3]. Given that glycolytic deregulation has been implicated in a number of diseases, such as cancer [4,5,6,7], malaria [8,9], and Trypanosoma [10,11], makes the rarity of natural product inhibitors of glycolysis particularly striking. Within the context of cancer, many tumors exhibit a shift in metabolism, favoring glycolysis, in what is known as the Warburg Effect [12].…”