RESUMO
Malaria continues to be one of the most devastating human diseases despite many efforts to limit its spread by prevention of infection or by pharmaceutical treatment of patients. We have conducted a screen for antiplasmodial compounds by using a natural product library. Here we report on cyclomarinâ A as a potent growth inhibitor of Plasmodium falciparum and the identification of its molecular target, diadenosine triphosphate hydrolase (PfAp3Aase), by chemical proteomics. Using a biochemical assay, we could show that cyclomarinâ A is a specific inhibitor of the plasmodial enzyme but not of the closest human homologue hFHIT. Co-crystallisation experiments demonstrate a unique binding mode of the inhibitor. One molecule of cyclomarinâ A binds a dimeric PfAp3Aase and prevents the formation of the enzymeâ substrate complex. These results validate PfAp3Aase as a new drug target for the treatment of malaria. We have previously elucidated the structurally unrelated regulatory subunit ClpC1 of the ClpP protease as the molecular target of cyclomarinâ A in Mycobacterium tuberculosis. Thus, cyclomarinâ A is a rare example of a natural product with two distinct and specific modes of action.
Assuntos
Produtos Biológicos/química , Oligopeptídeos/química , Hidrolases Anidrido Ácido/antagonistas & inibidores , Hidrolases Anidrido Ácido/metabolismo , Antimaláricos/química , Antimaláricos/metabolismo , Antimaláricos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Produtos Biológicos/metabolismo , Produtos Biológicos/farmacologia , Endopeptidase Clp/antagonistas & inibidores , Endopeptidase Clp/metabolismo , Humanos , Concentração Inibidora 50 , Simulação de Dinâmica Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/enzimologia , Proteínas de Neoplasias/antagonistas & inibidores , Proteínas de Neoplasias/metabolismo , Oligopeptídeos/metabolismo , Oligopeptídeos/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/enzimologia , Plasmodium falciparum/crescimento & desenvolvimento , Ligação Proteica , Estrutura Terciária de ProteínaRESUMO
Cultivation of myxobacteria of the Nannocystis genus led to the isolation and structure elucidation of a class of novel cyclic lactone inhibitors of elongation factorâ 1. Whole genome sequence analysis and annotation enabled identification of the putative biosynthetic cluster and synthesis process. In biological assays the compounds displayed anti-fungal and cytotoxic activity. Combined genetic and proteomic approaches identified the eukaryotic translation elongation factor 1α (EF-1α) as the primary target for this compound class. Nannocystinâ A (1) displayed differential activity across various cancer cell lines and EEF1A1 expression levels appear to be the main differentiating factor. Biochemical and genetic evidence support an overlapping binding site of 1 with the anti-cancer compound didemninâ B on EF-1α. This myxobacterial chemotype thus offers an interesting starting point for further investigations of the potential of therapeutics targeting elongation factorâ 1.