RESUMEN
Small molecule inhibitors provide powerful tools to characterize highly dynamic and complex eukaryotic cell pathways such as those mediating membrane traffic. However, a lack of easy and generalizable assays has constrained identification of novel inhibitors despite availability of diverse chemical libraries. Here, we report a facile growth-based strategy in yeast to screen for pathway-specific inhibitors. The approach uses well characterized synthetic genetic growth defects to guide design of cells genetically sensitized for inhibition of chosen pathways. With this strategy, we identified a family of piperazinyl phenylethanone compounds as inhibitors of traffic between the trans-Golgi network (TGN) and endosomes that depends on the clathrin adaptor complex AP-1. The compounds did not significantly alter other trafficking pathways involving the TGN or endosomes, indicating specificity. Compound treatment also altered localization of AP-1 in mammalian cells. These previously uncharacterized inhibitors will be useful for future studies of clathrin-mediated transport in yeast, and potentially in other organisms. Furthermore, the easily automated technology should be adaptable for identification of inhibitors of other cellular processes.
Asunto(s)
Complejo 1 de Proteína Adaptadora/antagonistas & inhibidores , Proteínas Adaptadoras del Transporte Vesicular/genética , Endosomas/metabolismo , Compuestos Orgánicos/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Red trans-Golgi/metabolismo , Complejo 1 de Proteína Adaptadora/metabolismo , Supervivencia Celular , Quitina/metabolismo , Genes Letales/genética , Estructura Molecular , Mutación/genética , Transporte de Proteínas/fisiología , LevadurasRESUMEN
The hindered diene 1 reacts with 3-methylcyclohexenone 6 catalyzed by triflimide to produce the Mukaiyama Michael product 7 (low-temperature quenching) or the [4+2] cycloadduct 8 (quenching at 0 degrees C). Reaction of the hindered diene 23 with 2-methylcyclohexenone 12 with 5:1 AlBr3:AlMe3 afforded a 71% yield of a 1.9:1 mixture of two cycloadducts. Hydrolysis of the major isomer gave the dione 27', a model for the BCD ring system of pentacyclic triterpenes. [reaction: see text].
Asunto(s)
Alcadienos/química , Ciclohexanonas/química , Imidas/química , Triterpenos/síntesis química , Compuestos de Aluminio/química , Catálisis , Ciclización , Hidrólisis , Estructura Molecular , Estereoisomerismo , Triterpenos/químicaRESUMEN
We prepared the primary adduct for the reaction of singlet dioxygen (1O2) with an arylphosphine by using the sterically hindered arylphosphine tris(o-methoxyphenyl)phosphine. The resulting phosphadioxirane has a dioxygen molecule triangularly bound to the phosphorus atom. Olefin trapping experiments show that the phosphadioxirane can undergo nonradical oxygen atom-transfer reactions. Under protic conditions, two different intermediates are formed during the reaction of singlet dioxygen with tris(o-methoxyphenyl)phosphine, namely, the corresponding hydroperoxy arylphosphine and a hydroxy phosphorane. Experiments with other arylphosphines possessing different electronic and steric properties demonstrate that the relative stability of the tris(o-methoxyphenyl)phosphadioxirane is due to both steric and electronic effects.
Asunto(s)
Compuestos Epoxi/química , Compuestos Heterocíclicos con 1 Anillo/química , Compuestos Organofosforados/química , Peróxidos/química , Fenómenos Químicos , Química Física , Cinética , Espectroscopía de Resonancia Magnética , Estructura Molecular , Oxidación-Reducción , Oxígeno/química , Fosfinas/química , Fósforo , Oxígeno Singlete/química , TemperaturaRESUMEN
We report the singlet oxygen sensitization properties of a series of bis-cyclometalated Ir(III) complexes (i.e., (bt)2Ir(acac), (bsn)2Ir(acac), and (pq)2Ir(acac); bt = 2-phenylbenzothiazole, bsn = 2-(1-naphthyl)benzothiazole, pq = 2-phenylquinoline, and acac = acetylacetonate). Complexes with acetylacetonate ancillary ligands give singlet oxygen quantum yields near unity (PhiDelta = (0.7-1.0) +/- 0.1), whether exciting the ligand-based state or the lowest energy excited state (MLCT + 3LC). The singlet oxygen quenching rates for these beta-diketonate complexes were found to be small [(5 +/- 2) x 105 to (6 +/- 0.2) x 106 M-1 s-1], roughly 3 orders of magnitude slower than the corresponding phosphorescence quenching rate. Similar complexes were prepared with glycine or pyridine tethered to the Ir(III) center (i.e., (bsn)2Ir(gly) and (bt)2Ir(py)Cl; gly = glycine and py = pyridine). The glycine and pyridine derivatives give high singlet oxygen yields (PhiDelta = (0.7-1.0) +/- 0.1).
Asunto(s)
Iridio/química , Compuestos Organometálicos/química , Fármacos Fotosensibilizantes/química , Oxígeno Singlete/químicaRESUMEN
Singlet oxygen reacts with Ir(I) and Rh(I) thiolato complexes to form the corresponding Ir(III) and Rh(III) peroxo thiolato complexes which do not undergo intramolecular oxidation of the thiolate moiety.