Argüelles J C, Carrillo D, Vicente-Soler J, García-Carmona F, Gacto M
Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Spain.
Curr Genet. 1993 May-Jun;23(5-6):382-7. doi: 10.1007/BF00312622.
The rise in cAMP level that follows the addition of glucose or 2,4-dinitrophenol (DNP) to stationary-phase cells of Saccharomyces cerevisiae was accompanied by a marked activation of trehalase (3-fold increase) and a concomitant deactivation of trehalose-6 phosphate synthase (50% of the basal levels). In glucose-grown exponential cells, which are deficient in glucose-induced cAMP signalling, the addition of glucose also prompted a decrease in trehalose-6 phosphate synthase, but had no effect on trehalase activity. Mutants defective in the RAS-adenylate cyclase pathway (ras1 ras2 bcy1 strain), as well as mutants containing greatly reduced protein kinase activity either cAMP-dependent (tpkw1 BCY1 strains) or cAMP-independent (tpk1w1 bcy1 strains), were unable to show glucose- or DNP-induced trehalase activation but still displayed a clear decrease in trehalose-6 phosphate synthase activity upon addition of these compounds. These data suggest that the activity of trehalose-6 phosphate synthase, as opposed to that of trehalase, is not controlled by the cAMP signalling pathway "in vivo". Trehalose-6 phosphate synthase was competitively inhibited by glucose (Ki = 15 mM) and resulted unaffected by ATP in assays performed "in vitro".
向酿酒酵母的静止期细胞中添加葡萄糖或2,4-二硝基苯酚（DNP）后，细胞内cAMP水平升高，同时海藻糖酶显著激活（增加3倍），海藻糖-6-磷酸合酶随之失活（降至基础水平的50%）。在葡萄糖培养的指数生长期细胞中，由于缺乏葡萄糖诱导的cAMP信号传导，添加葡萄糖也会促使海藻糖-6-磷酸合酶减少，但对海藻糖酶活性没有影响。RAS-腺苷酸环化酶途径缺陷的突变体（ras1 ras2 bcy1菌株），以及蛋白激酶活性大幅降低的突变体，无论是cAMP依赖性的（tpkw1 BCY1菌株）还是cAMP非依赖性的（tpk1w1 bcy1菌株），都无法表现出葡萄糖或DNP诱导的海藻糖酶激活，但在添加这些化合物后，海藻糖-6-磷酸合酶活性仍明显降低。这些数据表明，与海藻糖酶不同，海藻糖-6-磷酸合酶的活性在“体内”不受cAMP信号通路的控制。在“体外”实验中，海藻糖-6-磷酸合酶受到葡萄糖的竞争性抑制（Ki = 15 mM），且不受ATP的影响。
