REVERSIBLE INACTIVATION OF ISOCITRATE DEHYDROGENASE OF ESCHERICHIA-COLI ML308 DURING GROWTH ON ACETATE
REVERSIBLE INACTIVATION OF ISOCITRATE DEHYDROGENASE OF ESCHERICHIA-COLI ML308 DURING GROWTH ON ACETATE
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DOI：
10.1099/00221287-87-1-37
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发表时间：
1975-01-01
期刊：
影响因子：
--
通讯作者：
HOLMS, WH
中科院分区：
文献类型：
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作者：
BENNETT, PM;HOLMS, WH
在需氧生长ofEscherichia coliML 308上的乙酸作为唯一的碳源，异柠檬酸脱氢酶的表观合成抑制相对于其他碳源，如葡萄糖，不采用乙醛酸旁路作为回补序列的文化。当从乙酸盐培养基中取出细胞时，或者当加入使乙醛酸旁路的操作不必要的化合物时，异柠檬酸脱氢酶的活性迅速增加3- 4倍，但在恢复到乙酸盐培养基时又下降。活性的变化是迅速的，而且，可以证明在蛋白质合成的情况下。因此，该机制不太可能涉及酶蛋白的降解或新合成。草酰乙酸和乙醛酸对异柠檬酸脱氢酶有协同抑制作用，透析可解除这种抑制作用。由于来自乙酸盐代谢细胞的低酶活性提取物不能通过透析或加入广泛的代谢物来刺激，因此低分子量，可自由解离的效应物负责刺激或抑制活性。控制异柠檬酸脱氢酶允许有效利用乙酸作为唯一的碳源和能量源，但保留了细胞的能力，对营养状况的改善迅速作出反应。一项有限的调查表明，该机制在E.大肠杆菌在产气克雷伯氏菌、鼠伤寒沙门氏菌和粘质沙雷氏菌中至少各存在一种菌株。
During aerobic growth ofEscherichia coliML308 on acetate as sole carbon source, the apparent synthesis of isocitrate dehydrogenase was repressed relative to cultures on other carbon sources, such as glucose, which do not employ the glyoxylate bypass as an anaplerotic sequence. When cells were removed from an acetate medium, or when compounds were added which made the operation of the glyoxylate bypass unnecessary, the activity of isocitrate dehydrogenase rapidly increased 3- to 4-fold but fell again on restoration to an acetate medium. Changes in activity were rapid and, furthermore, could be demonstrated in the absence of protein synthesis. It is thus improbable that the mechanism involved degradation orde novosynthesis of the enzyme protein. Oxaloacetate and glyoxylate showed concerted inhibition of isocitrate dehydrogenase which could be relieved by dialysis. Because extracts of low enzyme activity, derived from acetate-metabolizing cells, could not be stimulated by dialysis or by addition of a wide range of metabolites, it is unlikely that low molecular weight, freely dissociable effectors were responsible for stimulation or inhibition of activity.Control of isocitrate dehydrogenase permitted the efficient utilization of acetate as sole source of carbon and energy but preserved the capacity of the cell to respond rapidly to an improvement in nutritional conditions. A limited survey showed that the mechanism is common but not universal among strains ofE. coliand occurs in at least one strain each ofKlebsiella aerogenes, Salmonella typhimuriumandSerratia marcescens.