RESUMO
New drugs that target Plasmodium species, the causative agents of malaria, are needed. The enzyme N-myristoyltransferase (NMT) is an essential protein, which catalyzes the myristoylation of protein substrates, often to mediate membrane targeting. We screened â¼1.8 million small molecules for activity against Plasmodium vivax (P. vivax) NMT. Hits were triaged based on potency and physicochemical properties and further tested against P. vivax and Plasmodium falciparum (P. falciparum) NMTs. We assessed the activity of hits against human NMT1 and NMT2 and discarded compounds with low selectivity indices. We identified 23 chemical classes specific for the inhibition of Plasmodium NMTs over human NMTs, including multiple novel scaffolds. Cocrystallization of P. vivax NMT with one compound revealed peptide binding pocket binding. Other compounds show a range of potential modes of action. Our data provide insight into the activity of a collection of selective inhibitors of Plasmodium NMT and serve as a starting point for subsequent medicinal chemistry efforts.
Assuntos
Aciltransferases/antagonistas & inibidores , Antimaláricos/síntese química , Antimaláricos/farmacologia , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Plasmodium/efeitos dos fármacos , Plasmodium/enzimologia , Aciltransferases/química , Animais , Sítios de Ligação , Linhagem Celular , Cristalografia por Raios X , Descoberta de Drogas , Ensaios de Triagem em Larga Escala , Humanos , Malária/tratamento farmacológico , Modelos Moleculares , Plasmodium falciparum/efeitos dos fármacos , Plasmodium vivax/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas , Relação Estrutura-AtividadeRESUMO
The attachment of myristate to the N-terminal glycine of certain proteins is largely a co-translational modification catalyzed by N-myristoyltransferase (NMT), and involved in protein membrane-localization. Pathogen NMT is a validated therapeutic target in numerous infectious diseases including malaria. In Plasmodium falciparum, NMT substrates are important in essential processes including parasite gliding motility and host cell invasion. Here, we generated parasites resistant to a particular NMT inhibitor series and show that resistance in an in vitro parasite growth assay is mediated by a single amino acid substitution in the NMT substrate-binding pocket. The basis of resistance was validated and analyzed with a structure-guided approach using crystallography, in combination with enzyme activity, stability, and surface plasmon resonance assays, allowing identification of another inhibitor series unaffected by this substitution. We suggest that resistance studies incorporated early in the drug development process help selection of drug combinations to impede rapid evolution of parasite resistance.
