ABSTRACT
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.
Subject(s)
Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , DNA Topoisomerase IV/antagonists & inhibitors , DNA Topoisomerase IV/chemistry , Glucosides/chemistry , Glucosides/pharmacology , Pyrroles/chemistry , Pyrroles/pharmacology , Topoisomerase II Inhibitors , Bacteria/drug effects , Magnetic Resonance Spectroscopy , Microbial Sensitivity TestsABSTRACT
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.
Subject(s)
Ganglia, Spinal/metabolism , Irritants/pharmacology , Lyngbya Toxins/pharmacology , Neurons/metabolism , Streptomyces/metabolism , Substance P/metabolism , Animals , CHO Cells , Calcium/metabolism , Capsaicin/pharmacology , Chemical Phenomena , Chemistry, Physical , Cricetinae , Female , Fermentation , Ganglia, Spinal/cytology , Ganglia, Spinal/drug effects , Isoenzymes/metabolism , Lyngbya Toxins/biosynthesis , Lyngbya Toxins/chemistry , Magnetic Resonance Spectroscopy , Mice , Mice, Inbred ICR , Microscopy, Confocal , Neurons/drug effects , Plasmids/genetics , Protein Kinase C/metabolism , Rats , Rats, Sprague-Dawley , Streptomyces/genetics , Tetradecanoylphorbol Acetate/pharmacologyABSTRACT
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.
