Adjustment of conformational flexibility of glyceraldehyde-3-phosphate dehydrogenase as a means of thermal adaptation and allosteric regulation
Adjustment of conformational flexibility of glyceraldehyde-3-phosphate dehydrogenase as a means of thermal adaptation and allosteric regulation
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DOI：
10.1007/s00249-008-0332-x
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发表时间：
2008-09-01
影响因子：
2
通讯作者：
Zavodszky, Peter
中科院分区：
文献类型：
--
作者：
Hajdu, Istvan;Bothe, Csaba;Zavodszky, Peter
来自海栖热袍菌的 3-磷酸甘油醛脱氢酶 (GAPDH) (TmGAPDH) 是一种热稳定酶 (T-m = 102 摄氏度)，在接近 80 摄氏度的温度下完全活跃，但在室温下活性非常低。为了寻找对此行为的解释，我们通过氢-氘交换测量了蛋白质的构象灵活性，并将结果与用兔肌肉 GAPDH (RmGAPDH) 获得的结果进行了比较。在室温下，TmGAPDH的构象灵活性远低于RmGAPDH，但随着温度的升高而增加，并且在海栖热袍菌生理温度附近变得与RmGAPDH相当。利用两种酶现有的三维结构，我们比较了反映蛋白质原子局部迁移率的 B 因子。 B 因子的最大差异出现在辅酶和 NAD 结合区域。 TmGAPDH 在室温下活性低的可能原因是酶功能所需的运动受到限制。这些发现支持“相应状态”的观点，该观点声称，在进化的时间跨度中，蛋白质的整体构象灵活性在其相应的生理温度下得到了保留。
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from Thermotoga maritima (TmGAPDH) is a thermostable enzyme (T-m = 102 degrees C), which is fully active at temperatures near 80 degrees C but has very low activity at room temperature. In search for an explanation of this behavior, we measured the conformational flexibility of the protein by hydrogen-deuterium exchange and compared the results with those obtained with GAPDH from rabbit muscle (RmGAPDH). At room temperature, the conformational flexibility of TmGAPDH is much less than that of RmGAPDH, but increases with increasing temperature and becomes comparable to that of RmGAPDH near the physiological temperature of Thermotoga maritima. Using the available three-dimensional structures of the two enzymes, we compared the B factors that reflect the local mobility of protein atoms. The largest differences in B factors are seen in the coenzyme and NAD binding regions. The likely reason for the low activity of TmGAPDH at room temperature is that the motions required for enzyme functions are restricted. The findings support the idea of "corresponding states" which claims that over the time span of evolution, the overall conformational flexibility of proteins has been preserved at their corresponding physiological temperatures.