Biology subjects

Partridge, A.

Publications and source records attributed to Partridge, A..

3 recordsLinked to original sources

bioRxiv2026

Mutations within and outside the PfFNT transport pathway drive MMV007839 resistance in Plasmodium falciparum

Plasmodium falciparum, the parasite responsible for the majority of malaria cases and deaths worldwide, poses a major global health challenge due to its ability to rapidly develop resistance to antimalarial drugs. To circumvent existing resistance pathways, it is of interest to identify both new inhibitors and new therapeutic targets within the parasite. One such target is the Plasmodium falciparum Formate-Nitrite Transporter (PfFNT), which mediates essential lactate and proton (H+) export from the parasite cytosol during the intra-erythrocytic stage. Several inhibitors of PfFNT have been identified that block lactate/H transport and/or kill parasites in vitro, including MMV007839, which binds within the substrate transport pathway as revealed by cryo- EM structures. However, three resistance-conferring mutations have previously been identified following prolonged in vitro exposure of parasites to PfFNT inhibitors. Here, we performed further in vitro evolution experiments with MMV007839 in P. falciparum and identified two additional mutations in PfFNT, V200L and L198M, the latter of which is located outside the substrate transport pathway. These mutations are associated with 6-fold and 13-fold changes in the IC50 of MMV007839. Using molecular dynamics simulations, and thermodynamic integration, we show that these mutations, together with previously identified resistance mutations, destabilise inhibitor binding within the transport pathway; and we suggest the molecular mechanisms underlying this destabilisation. Finally, using both molecular docking and additional simulations, we suggest new sites where additional mutations that confer resistance to PfFNT inhibitors may arise. Author SummaryMalaria parasites are becoming resistant to existing drugs, creating an urgent need for new treatments. One promising drug target is the Plasmodium falciparum Formate-Nitrite Transporter (PfFNT), which the parasite needs to remove waste products and survive during infection. Although some compounds that block PfFNT have been identified, several mutations in the protein can make these compounds ineffective. To better understand how resistance might develop, we exposed malaria parasites to the PfFNT inhibitor MMV007839 in the laboratory and identified two new resistance-related mutations, one of which lies outside the MMV007839-binding site. We also used computer models to predict other regions where resistance-conferring mutations could occur. These findings help assess PfFNT as a drug target and provide guidance for designing new drugs that are less likely to be undermined by resistance.

biophysics↗

bioRxiv2021

Identification of an inhibitory pocket in falcilysin bound by chloroquine provides a new avenue for malaria drug development

Despite their widespread use, our understanding of how many antiparasitic drugs work remains limited. We used mass-spectrometry based cellular thermal shift assay (MS-CETSA) to identify possible protein targets of several malaria drugs and drug candidates. We found that falcilysin (FLN) is a common target for several quinoline drugs including chloroquine and mefloquine, as well as drug candidates MK-4815, MMV000848 and MMV665806. At pH 7.5, these compounds all inhibit FLN proteolytic activity with IC50 values ranging from 1.6 to 67.9 {micro}M. Their interaction with FLN was systematically probed by isothermal titration calorimetry and X-ray crystallography, revealing a shared hydrophobic pocket in the catalytic chamber of the enzyme. Characterization of transgenic cell lines with depleted FLN expression demonstrated statistically significant increases in susceptibility towards chloroquine, mefloquine, MK-4815 and MMV000848. Taken together, our findings point to a multimodal mechanism of action for several commonly used anti-malaria drugs. Importantly, a common allosteric pocket of FLN appears amenable to inhibition, providing a structural basis to guide the development of novel drugs against malaria.

microbiology↗

bioRxiv2019

Macrocyclization of an all-D linear peptide improves target affinity and imparts cellular activity: A novel stapled α-helical peptide modality

Peptide-based inhibitors hold great potential for targeted modulation of intracellular protein-protein interactions (PPIs) by leveraging vast chemical space relative to primary structure via sequence diversity as well as conformationally through varying secondary and tertiary structures. However, the development of peptide therapeutics has been hindered because of their limited conformational stability, proteolytic sensitivity and cell permeability. Several contemporary peptide design strategies address these issues to varying degrees. Strategic macrocyclization through optimally placed chemical braces such as olefinic hydrocarbon crosslinks, commonly referred to as staples, may address these issues by i) restricting conformational freedom to improve target affinities, ii) improving proteolytic resistance, and iii) enhancing cell permeability. Conversely, molecules constructed entirely from D-amino acids are hyper-resistant to proteolytic cleavage, but generally lack conformational stability and membrane permeability. Since neither approach is a complete solution, we have combined these strategies to identify the first examples of all-D -helical stapled and stitched peptides. As a template, we used a recently reported all D-linear peptide that is a potent inhibitor of the p53-Mdm2 interaction, but is devoid of cellular activity. To design both stapled and stitched all-D-peptide analogues, we used computational modelling to predict optimal staple placement. The resultant novel macrocyclic all D-peptide was determined to exhibit increased -helicity, improved target binding, complete proteolytic stability and, most notably, cellular activity.

biochemistry↗