RESUMO
The discovery of Streptomyces-produced streptomycin founded the age of tuberculosis therapy. Despite the subsequent development of a curative regimen for this disease, tuberculosis remains a worldwide problem, and the emergence of multidrug-resistant Mycobacterium tuberculosis has prioritized the need for new drugs. Here we show that new optimized derivatives from Streptomyces-derived griselimycin are highly active against M. tuberculosis, both in vitro and in vivo, by inhibiting the DNA polymerase sliding clamp DnaN. We discovered that resistance to griselimycins, occurring at very low frequency, is associated with amplification of a chromosomal segment containing dnaN, as well as the ori site. Our results demonstrate that griselimycins have high translational potential for tuberculosis treatment, validate DnaN as an antimicrobial target, and capture the process of antibiotic pressure-induced gene amplification.
Assuntos
Antituberculosos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Terapia de Alvo Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Peptídeos Cíclicos/farmacologia , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Animais , Antituberculosos/química , Antituberculosos/uso terapêutico , Linhagem Celular Tumoral , Cristalografia por Raios X , DNA Polimerase Dirigida por DNA , Modelos Animais de Doenças , Desenho de Fármacos , Humanos , Camundongos , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Mycobacterium smegmatis/efeitos dos fármacos , Mycobacterium smegmatis/enzimologia , Mycobacterium tuberculosis/enzimologia , Peptídeos Cíclicos/química , Peptídeos Cíclicos/uso terapêutico , Estrutura Secundária de Proteína , Streptomyces/química , Streptomyces/efeitos dos fármacos , Streptomyces/metabolismo , Tuberculose Resistente a Múltiplos Medicamentos/microbiologiaRESUMO
Pau d'arco is a plant-derived traditional medicine that acts by poorly understood molecular mechanisms. Here, we studied the effect of pau d'arco on the cytoprotective transcription factor Nrf2. An aqueous extract of pau d'arco stimulated Nrf2-dependent gene expression and led to nuclear localization of Nrf2 in vitro. Chromatographic separation and mass spectrometry of the extract identified benzene trioles or benzene tetraoles within the active fractions. The extract stimulated the mitogen-activated protein kinase/extracellular-signal-regulated kinase kinase (MEK)/extracellular-signal-regulated kinase (ERK1/2) pathway. The pharmacological inhibition of MEK, but not of p38 mitogen-activated protein kinase, glycogen synthase kinase-3 or phosphoinositide 3-kinase was required for the activation of Nrf2-dependent gene expression by pau d'arco, but not for the nuclear translocation of Nrf2. In vivo pau d'arco increased the expression of Nrf2-target genes in the intestine. The results suggest that the activation of Nrf2 could mediate beneficial effects of pau d'arco, in particular in the intestine.