REGULATION OF AN ENZYME BY PHOSPHORYLATION AT THE ACTIVE-SITE
REGULATION OF AN ENZYME BY PHOSPHORYLATION AT THE ACTIVE-SITE
复制标题
DOI：
10.1126/science.2204109
复制
发表时间：
1990-08-31
期刊：
影响因子：
56.9
通讯作者：
STROUD, RM
中科院分区：
文献类型：
--
作者：
HURLEY, JH;DEAN, AM;STROUD, RM
大肠杆菌的异柠檬酸脱氢酶是一类普遍存在的受共价修饰调节的酶的例子。在酶-底物复合物的三维结构中，异柠檬酸与调节性磷酸化位点 Ser113 形成氢键。 Asp113 和 Glu113 突变体的结构模拟了磷酸化酶的失活，与野生型相比，其构象变化极小，与磷酸化酶一样。 基于观察到的结构的计算表明，当通过磷酸化或定点诱变引入负电荷时，静电势的变化足以使酶失活。因此，配体结合位点的直接相互作用是通过磷酸化调节蛋白质活性中从变构位点诱导构象变化的另一种机制。
The isocitrate dehydrogenase of Escherichia coli is an example of a ubiquitous class of enzymes that are regulated by covalent modification. In the three-dimensional structure of the enzyme-substrate complex, isocitrate forms a hydrogen bond with Ser113, the site of regulatory phosphorylation. The structures of Asp113 and Glu113 mutants, which mimic the inactivation of the enzyme by phosphorylation, show minimal conformational changes from wild type, as in the phosphorylated enzyme. Calculations based on observed structures suggest that the changes in electrostatic potential when a negative charge is introduced either by phosphorylation or site-directed mutagenesis is sufficient to inactivate the enzyme. Thus, direct interaction at a ligand binding site is an alternative mechanism to induced conformational changes from an allosteric site in the regulation of protein activity by phosphorylation.