Biology subjects

de Souza, M. L.

Publications and source records attributed to de Souza, M. L..

4 recordsLinked to original sources

bioRxiv2025

Shared Binding Site but Divergent Resistance Profiles Uncover Novel Resistance Mechanisms in Plasmodium HSP90 Inhibitors

Drug resistance is a widespread problem across therapeutic areas including malaria, but what accounts for resistance propensity remains poorly understood. Here, we reveal that two HSP90 inhibitors targeting the identical ATP-binding site exhibit dramatically different resistance profiles in P. falciparum. Geldanamycin readily selected 10 distinct resistance mutations conferring up to 22-fold resistance, while AUY-922 required 44 weeks to yield a single A41S mutation with only 2-fold resistance to AUY-922 but not to geldanamycin. Resistance mapping in parasites and yeast revealed geldanamycin resistance mutations distributed throughout the binding pocket whereas AUY-922 resistance mutations localized close to the ATP-binding site. Unexpectedly, the A41S mutation enhanced AUY-922 binding affinity without changing geldanamycin binding. In silico analysis suggested this enhancement occurs through additional hydrogen bonding, yet stronger binding correlated with resistance. In yeast, A41S had opposite effects, hypersensitizing cells to all HSP90 inhibitors tested. Additionally, conditional HSP90 knockdown increased geldanamycin sensitivity but left AUY-922 activity unaffected, indicating different target dependencies despite shared binding sites. Based on these data, we propose a multi-target hypothesis where AUY-922s lower resistance risk stems from engaging multiple HSP90 family members. Our findings reveal how enhanced drug-target binding can paradoxically correlate with resistance and demonstrate that resistance risk cannot be predicted from binding site identity alone, providing insights for developing more durable drugs across therapeutic areas.

microbiology↗

bioRxiv2025

Targeting Aurora kinases as essential cell cycle regulators to deliver multi-stage antimalarials against Plasmodium falciparum

Kinases that play critical roles in the development and adaptation of Plasmodium falciparum present novel opportunities for chemotherapeutic intervention. Of particular interest are mitotic kinases that regulate the proliferation of the parasites by controlling nuclear division, segregation and cytokinesis. We evaluated the potential of human Aurora kinase (Aur) inhibitors to inhibit P. falciparum development by targeting members of the Aurora-related kinase (Ark) family in this parasite. Several human AurB inhibitors exhibited multistage potency (<250 nM) against all proliferative stages of parasite development, including asexual blood stages, liver schizonts and male gametes. Among the most potent compounds, hesperadin and AT83 exhibit >1000x selectivity towards the parasite without concerns about mammalian cell toxicity. Importantly, we identified PfArk1 as the principal vulnerable Ark family member, with specific inhibition of PfArk1 as the primary target for hesperadin and the human anaplastic lymphoma kinase (ALK) inhibitor TAE684. Hesperadins whole-cell and protein activity validates it as a unique PfArk1 tool compound. Inhibition of PfArk1 results in the parasites inability to complete mitotic processes, presenting with unsegregated, multi-lobed nuclei caused by aberrant microtubule organization. This suggests that PfArk1 is the main Aur mitotic kinase in proliferative stages of Plasmodium, characterized by bifunctional AurA and B activity. This paves the way for drug discovery campaigns based on hesperadin targeting PfArk1.

molecular biology↗

bioRxiv2021

Discovery of imidazole-based inhibitors of P. falciparum cGMP-dependent protein kinase

The discovery of new targets for treatment of malaria and in particular those aimed at the pre-erythrocytic stage in the life cycle, advanced with the demonstration that orally administered inhibitors of Plasmodium falciparum cGMP-dependent protein kinase (PfPKG) could clear infection in a murine model. This enthusiasm was tempered by unsatisfactory safety and/or pharmacokinetic issues found with these chemotypes. To address the urgent need for new scaffolds, this manuscript presents initial structure-activity relationships in an imidazole scaffold at four positions, representative in vitro ADME, hERG characterization and cell-based anti-parasitic activity. This series of PfPKG inhibitors has good in vitro PfPKG potency, low hERG activity and cell-based anti-parasitic activity against multiple Plasmodium species that appears to correlate with in vitro potency.

pharmacology and toxicology↗

bioRxiv2021

Discovery of novel potent, cell-permeable inhibitors of P. falciparum cGMP-dependent protein kinase.

The discovery of new targets for treatment of malaria advanced with the demonstration that orally administered inhibitors of Plasmodium falciparum cGMP-dependent protein kinase (PfPKG) could clear infection in a murine model. This enthusiasm was tempered by unsatisfactory safety and/or pharmacokinetic issues found with these chemotypes. To address the urgent need for new scaffolds, we recently reported the discovery and optimization of novel, potent isoxazole-based PfPKG inhibitors that lacked any obvious safety warnings. This manuscript presents representative in vitro ADME, hERG characterization and cell-based antiparasitic activity of these PfPKG inhibitors. We also report the discovery and structure-activity relationships of a new series with good potency, low hERG activity and cell-based anti-parasitic activity comparable to a literature standard.

pharmacology and toxicology↗