RESUMO
The abuse of antibacterial drugs imposes a selection pressure on bacteria that has driven the evolution of multidrug resistance in many pathogens. Our efforts to discover novel classes of antibiotics to combat these pathogens resulted in the discovery of amycolamicin (AMM). The absolute structure of AMM was determined by NMR spectroscopy, X-ray analysis, chemical degradation, and modification of its functional groups. AMM consists of trans-decalin, tetramic acid, two unusual sugars (amycolose and amykitanose), and dichloropyrrole carboxylic acid. The pyranose ring named as amykitanose undergoes anomerization in methanol. AMM is a potent and broad-spectrum antibiotic against Gram-positive pathogenic bacteria by inhibiting DNA gyrase and bacterial topoisomerase IV. The target of AMM has been proved to be the DNA gyrase B subunit and its binding mode to DNA gyrase is different from those of novobiocin and coumermycin, the known DNA gyrase inhibitors.
Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , DNA Topoisomerase IV/antagonistas & inibidores , DNA Topoisomerase IV/química , Glucosídeos/química , Glucosídeos/farmacologia , Pirróis/química , Pirróis/farmacologia , Inibidores da Topoisomerase II , Bactérias/efeitos dos fármacos , Espectroscopia de Ressonância Magnética , Testes de Sensibilidade MicrobianaRESUMO
A new teleocidin analog was isolated from the fermentation medium of Streptomyces sp. MM216-87F4 and its structure was elucidated as 14-O-(N-acetylglucosaminyl) teleocidin A (GlcNAc-TA). GlcNAc-TA induces the translocation of protein kinases Calpha and theta fused with enhanced green fluorescent protein (PKCalpha-EGFP and PKCtheta-EGFP) to the plasma membrane in stable transfectants, and reduces intracellular calcium mobilization induced by agonists of G-protein coupled receptors in various cell lines without causing irritation of the mouse ear. Further, GlcNAc-TA sensitizes the release of excitatory neuropeptides substance P induced by capsaicin from primary-cultured dorsal root ganglion (DRG) neurons of the rat and GlcNAc-TA alone also triggers substance P release in a dose-dependent manner. This study provides the first observation that a teleocidin analog without a free hydroxyl group at C-14 acts as a PKC activator and directly induces the release of excitatory neuropeptide.
Assuntos
Gânglios Espinais/metabolismo , Irritantes/farmacologia , Toxinas de Lyngbya/farmacologia , Neurônios/metabolismo , Streptomyces/metabolismo , Substância P/metabolismo , Animais , Células CHO , Cálcio/metabolismo , Capsaicina/farmacologia , Fenômenos Químicos , Físico-Química , Cricetinae , Feminino , Fermentação , Gânglios Espinais/citologia , Gânglios Espinais/efeitos dos fármacos , Isoenzimas/metabolismo , Toxinas de Lyngbya/biossíntese , Toxinas de Lyngbya/química , Espectroscopia de Ressonância Magnética , Camundongos , Camundongos Endogâmicos ICR , Microscopia Confocal , Neurônios/efeitos dos fármacos , Plasmídeos/genética , Proteína Quinase C/metabolismo , Ratos , Ratos Sprague-Dawley , Streptomyces/genética , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
Migrastatin and its analogs have various biological activities such as inhibition of cell migration and anchorage-independent growth of cancer cells. Although its biosynthesis and chemical synthesis have been under investigation, little is known about the biological target of migrastatin. Here, we found that migrastatin inhibited intracellular calcium mobilization induced by carbachol in neuroblastoma SK-N-SH cells without affecting Ca2+ mobilization and cAMP accumulation induced by ligands of other receptors. The binding of [3H] N-methylscopolamine, an antagonist for muscarinic receptor was also inhibited by migrastain. Functionally, migrastatin inhibited Ca2+ mobilization induced by carbachol in primary cultures of smooth muscle cells of rat bladder. This study reveals that migrastatin acts as a muscarinic acetylcholine receptor antagonist.