RESUMEN
Incubation of Candida albicans yeast cells with human luteinizing hormone (hLH), human chorionic gonadotrophin (hCG) or glucagon produced a significant rise in cAMP total levels. The effect of these hormones in permeabilized cells of the fungus produced a 2-3 fold increase in the Mg2+, GTP-dependent adenylyl cyclase activity as well as full activation of the cAMP-dependent protein kinase (PKA) activity. These results indicate that the interaction of the mammalian hormones with the fungus triggered the cAMP activation cascade in a similar way to that found in higher eukaryotic organisms.
Asunto(s)
Candida albicans/metabolismo , Gonadotropina Coriónica/farmacología , AMP Cíclico/metabolismo , Glucagón/farmacología , Hormona Luteinizante/farmacología , Adenilil Ciclasas/metabolismo , Permeabilidad de la Membrana Celular/efectos de los fármacos , AMP Cíclico/análisis , AMP Cíclico/biosíntesis , Humanos , Magnesio/análisis , Magnesio/metabolismo , Proteínas Quinasas/metabolismo , Sistemas de Mensajero Secundario , Tolueno/farmacologíaRESUMEN
GTP, GTP-gamma-S and Gpp(NH)p produced a significant activation of Mg2(+)-dependent adenylyl cyclase in permeabilized cells of Candida albicans. This activation was inhibited by GDP-beta-S. Maximal stimulation (4-6 fold) was obtained when Mg2+ and GTP-gamma-S were added during permeabilization. The guanine nucleotide-stimulated activity could be further activated by glucagon in a dose dependent manner being the maximal stimulation (4-5 fold) attained at 10(-6) M glucagon. Addition of the hormone to yeast cells incubated under conditions conducive to produce germ tubes blocked hyphal development and promoted multibudded cell morphology.
Asunto(s)
Adenilil Ciclasas/metabolismo , Candida albicans/enzimología , Glucagón/farmacología , Guanosina Trifosfato/análogos & derivados , Guanosina Trifosfato/farmacología , Guanilil Imidodifosfato/farmacología , Tionucleótidos/farmacología , Candida albicans/citología , Candida albicans/efectos de los fármacos , Activación Enzimática , Guanosina 5'-O-(3-Tiotrifosfato) , Cinética , Magnesio/farmacologíaRESUMEN
Intracellular levels of cAMP and specific activities of adenylate cyclase, cAMP phosphodiesterase and cAMP-dependent protein kinase were measured during filamentation in the dimorphic fungus Candida albicans. Enzymatic assays were performed in permeabilized cells under conditions prevented endogenous proteolysis. The variations observed in cAMP levels were mainly accounted for by variations in the specific activities of adenylate cyclase and cAMP phosphodiesterase at different stages during germ tube formation. cAMP-dependent protein kinase, measured with kemptide as exogenous substrate, was developmental regulated. Some properties of the enzymatic activities from cell-free extracts are described.