COMMITMENT TO SPORULATION AND INDUCTION OF GLUCOSE-PHOSPHOENOLPYRUVATE-TRANSFERASE
COMMITMENT TO SPORULATION AND INDUCTION OF GLUCOSE-PHOSPHOENOLPYRUVATE-TRANSFERASE
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DOI：
10.1016/0304-4165(70)90115-7
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发表时间：
1970-01-01
期刊：
影响因子：
--
通讯作者：
GALLIERS, E
中科院分区：
文献类型：
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作者：
FREESE, E;KLOFAT, W;GALLIERS, E
当葡萄糖在营养产孢培养基中呈指数增长时，它会抑制枯草芽孢杆菌的产孢，而在t0之后的任何时间添加葡萄糖则不会，此时生长已开始从指数速度下降。在这之后，B。枯草细胞对葡萄糖产生孢子。虽然在生长末期，糖酵解酶的特定活性没有显著变化，这可以解释这种对葡萄糖抑制的抗性，但葡萄糖-磷酸烯醇丙酮酸-转移酶系统确实发生了巨大变化。后一种酶系统在指数生长阶段由葡萄糖诱导，葡萄糖的摄取也是如此，而atp依赖性葡萄糖激酶的比活性在整个生长过程中保持恒定，不受葡萄糖添加的影响。磷酸烯醇丙酮酸转移酶（而不是葡萄糖激酶）也磷酸化α-甲基葡萄糖苷，这可以更有利地用于分析酶。在生长末期，葡萄糖的摄取和葡萄糖-磷酸烯醇丙酮酸转移酶的活性下降，这与葡萄糖无法抑制承诺细胞的产孢有关。这种下降也发生在预诱导细胞中，这与预诱导细胞在葡萄糖从培养基中退出后仍能进入与葡萄糖有关的产孢过程有关。为了证实这些发现，一种突变体，不依赖果糖或葡萄糖胺生长，几乎不依赖甘油，在葡萄糖上生长缓慢，并且缺乏磷酸烯醇丙酮酸转移酶活性，当葡萄糖存在于整个生长和产孢过程中时，可以产孢。
Glucose suppresses sporulation ofBacillus subtiliswhen it is present during exponential growth in nutrient sporulation medium but not when it is added at any time afterT0, the time at which growth has started to decline from the exponential rate. After this time,B. subtiliscells are committed with respect to glucose to sporulate. While toward the end of growth no significant changes in the specific activities of the glycolytic enzymes occur which could explain this resistance to glucose suppression, the glucose-phosphoenolpyruvate-transferase system does change drastically. The latter enzyme system is inducible by glucose during the exponential growth phase and so is the uptake of glucose, whereas the specific activity of the ATP-dependent glucokinase remains constant throughout growth and is not influenced by glucose addition. The phosphoenolpyruvate-transferase (but not the glucokinase) also phosphorylates α-methylglucoside which can be more advantageously used for assaying the enzyme. Toward the end of growth, the uptake of glucose and the activity of glucose-phosphoenolpyruvate-transferase decline in correlation with the inability of glucose to suppress sporulation of committed cells. This decline occurs also in pre-induced cells, again in correlation with the fact that preinduced cells can still enter the commitment of sporulation with respect to glucose after glucose is withdrawn from the medium. In confirmation of these findings, a mutant, which grows not on fructose or glucosamine, scarcely on glycerol, and slowly on glucose, and which lacks phosphoenolpyruvate-transferase activity, can sporulate when glucose is present throughout growth and sporulation.