RESUMO
The Plasmodium falciparum proteasome is a potential antimalarial drug target. We have identified a series of amino-amide boronates that are potent and specific inhibitors of the P. falciparum 20S proteasome (Pf20S) ß5 active site and that exhibit fast-acting antimalarial activity. They selectively inhibit the growth of P. falciparum compared with a human cell line and exhibit high potency against field isolates of P. falciparum and Plasmodium vivax They have a low propensity for development of resistance and possess liver stage and transmission-blocking activity. Exemplar compounds, MPI-5 and MPI-13, show potent activity against P. falciparum infections in a SCID mouse model with an oral dosing regimen that is well tolerated. We show that MPI-5 binds more strongly to Pf20S than to human constitutive 20S (Hs20Sc). Comparison of the cryo-electron microscopy (EM) structures of Pf20S and Hs20Sc in complex with MPI-5 and Pf20S in complex with the clinically used anti-cancer agent, bortezomib, reveal differences in binding modes that help to explain the selectivity. Together, this work provides insights into the 20S proteasome in P. falciparum, underpinning the design of potent and selective antimalarial proteasome inhibitors.
Assuntos
Compostos de Boro/farmacologia , Malária Falciparum/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma/química , Inibidores de Proteassoma/farmacologia , Administração Oral , Animais , Compostos de Boro/administração & dosagem , Compostos de Boro/química , Domínio Catalítico , Humanos , Malária Falciparum/enzimologia , Malária Falciparum/parasitologia , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Modelos Moleculares , Plasmodium falciparum/enzimologia , Inibidores de Proteassoma/administração & dosagem , Inibidores de Proteassoma/químicaRESUMO
Mitochondrial Carriers (MCs) are responsible for fluent traffic of a variety of compounds that need to be shuttled via mitochondrial inner membranes to maintain cell metabolism. The ADP/ATP Carriers (AACs) are responsible for the import of ADP inside the mitochondria and the export of newly synthesized ATP. In human, four different AACs isoforms are described which are expressed in tissue-specific manner. They are involved in different genetic diseases and play a role in cancerogenesis. Up to now only the structures of the bovine (isoform 1) and yeast (isoforms 2 and 3) AAC have been determined in one particular conformation, obtained in complex with the CATR inhibitor. Herein, we report that full-length human ADP/ATP Carriers isoform 1 and 3 were successfully expressed in cell-free system and purified in milligram amounts in detergent-solubilized state. The proteins exhibited the expected secondary structure content. Thermostability profiles showing stabilization by the CATR inhibitor suggest that the carriers are well folded.