Tkachenko A G, Pshenichnov M R, Salakhetdinova O Ia, Nesterova L Iu
Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Perm, Russia.
Mikrobiologiia. 1998 Sep-Oct;67(5):601-6.
The effect of a temperature increase to 52 degrees C or the addition of ethanol (6%) to an exponential Escherichia coli culture on putrescine and potassium transport was studied. The first stage of heat shock was accompanied by a decrease in the extent of DNA supercoiling, due to the dissociation of the putrescine-DNA complex. The loss of potassium ions at this phase produced a synergistic effect. The second phase of the heat shock was characterized by a reversal in the direction of putrescine and potassium transport, which was accompanied by restoration of the prestress extent of DNA supercoiling. An increase in the ATP pool and cell energy charge resulting from the uncoupling of the energy metabolism and synthetic processes also played an important role in the restoration of the DNA initial topology at the second phase of the heat shock via the activation of the energy-dependent gyrase or the heat shock protein DnaK. A mechanism is suggested that explains the involvement of putrescine in the regulation of DNA topology, which is a universal regulator of gene expression under stress, heat shock in particular.
研究了将指数生长的大肠杆菌培养物温度升至52摄氏度或添加乙醇（6%）对腐胺和钾转运的影响。热休克的第一阶段伴随着DNA超螺旋程度的降低，这是由于腐胺-DNA复合物的解离。此阶段钾离子的流失产生了协同效应。热休克的第二阶段的特征是腐胺和钾转运方向的逆转，同时伴随着DNA超螺旋预应力程度的恢复。能量代谢与合成过程解偶联导致的ATP库增加和细胞能量电荷增加，在热休克第二阶段通过激活能量依赖性促旋酶或热休克蛋白DnaK恢复DNA初始拓扑结构方面也发挥了重要作用。提出了一种机制，解释了腐胺参与DNA拓扑结构调控的过程（DNA拓扑结构是应激特别是热休克下基因表达的通用调节因子）。
