Energy Metabolism Response to Low-Temperature and Frozen Conditions in Psychrobacter cryohalolentis
Energy Metabolism Response to Low-Temperature and Frozen Conditions in Psychrobacter cryohalolentis
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DOI：
10.1128/aem.02193-08
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发表时间：
2009-02-01
影响因子：
4.4
通讯作者：
Christner, Brent C.
中科院分区：
文献类型：
--
作者：
Amato, Pierre;Christner, Brent C.
对低温活性酶的研究提供了有关嗜冷菌分子和生化特性的基本信息;然而，补偿低温代谢的生理策略仍然知之甚少。我们研究了在22 ° C和-80 ° C之间的八个温度下孵育的低温嗜盐嗜冷杆菌K5中ATP和ADP的细胞池。细胞ATP和ADP浓度随着温度的降低而增加，并且在作为冷冻悬浮液（< -5 ° C）孵育的细胞中观察到最显著的增加。呼吸解偶联显着降低这种温度依赖性的反应，表明质子动力所需的能量适应冻结条件。由于ATP和ADP是代谢和能量守恒反应中的关键底物，增加它们的浓度可以提供抵消动力学温度效应的策略，从而在低温下保持反应速率。腺苷酸水平在冷冻后< 1小时显著增加，并且当细胞被电击以模拟在冰的液体部分中遇到的升高的溶质浓度时也显著增加。总之，这些数据表明，细胞能量代谢的实质性变化是细胞适应冷冻过程中遇到的低温和水活度条件所必需的。这种生理反应可能代表了低温下的一种重要的生化补偿机制，与冷冻过程中的细胞存活有关，并且对微生物在冰冷环境中的持久性很重要。
Studies of cold-active enzymes have provided basic information on the molecular and biochemical properties of psychrophiles; however, the physiological strategies that compensate for low-temperature metabolism remain poorly understood. We investigated the cellular pools of ATP and ADP in Psychrobacter cryohalolentis K5 incubated at eight temperatures between 22 degrees C and -80 degrees C. Cellular ATP and ADP concentrations increased with decreasing temperature, and the most significant increases were observed in cells that were incubated as frozen suspensions (< -5 degrees C). Respiratory uncoupling significantly decreased this temperature-dependent response, indicating that the proton motive force was required for energy adaptation to frozen conditions. Since ATP and ADP are key substrates in metabolic and energy conservation reactions, increasing their concentrations may provide a strategy for offsetting the kinetic temperature effect, thereby maintaining reaction rates at low temperature. The adenylate levels increased significantly < 1 h after freezing and also when the cells were osmotically shocked to simulate the elevated solute concentrations encountered in the liquid fraction of the ice. Together, these data demonstrate that a substantial change in cellular energy metabolism is required for the cell to adapt to the low temperature and water activity conditions encountered during freezing. This physiological response may represent a critical biochemical compensation mechanism at low temperature, have relevance to cellular survival during freezing, and be important for the persistence of microorganisms in icy environments.