GLUCOKINASE OF ESCHERICHIA-COLI - INDUCTION IN RESPONSE TO THE STRESS OF OVEREXPRESSING FOREIGN PROTEINS
GLUCOKINASE OF ESCHERICHIA-COLI - INDUCTION IN RESPONSE TO THE STRESS OF OVEREXPRESSING FOREIGN PROTEINS
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DOI：
10.1006/abbi.1995.1333
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发表时间：
1995-06-01
影响因子：
3.9
通讯作者：
PEDERSEN, PL
中科院分区：
文献类型：
--
作者：
ARORA, KK;PEDERSEN, PL
已知多种应激条件，例如热休克、乙醇、渗透压休克、葡萄糖剥夺和氧化应激，诱导特定蛋白质的合成。在这里，我们报告了在大肠杆菌中诱导一种蛋白质，该蛋白质是响应于迄今为止未鉴定的应激条件而引起的，即，外源蛋白的过度表达。被鉴定为葡糖激酶（EC 2.7.1.2）的诱导蛋白质的产生水平比野生型E.当外源蛋白在碱性磷酸酶（phoA）启动子的控制下表达时，用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳原位复性活性染色法测定，该细菌葡萄糖激酶的分子量约为47 kDa，对葡萄糖磷酸化具有高度的特异性。大肠杆菌酶是低K-m葡萄糖己糖激酶。该酶与高等真核生物己糖激酶的兔抗血清发生交叉反应，表明与哺乳动物己糖激酶有一定的序列相似性。在正常条件下，E.大肠杆菌葡萄糖激酶在葡萄糖代谢中起次要作用，然而，在合成代谢应激条件下，可能需要这种糖酵解酶来补充葡萄糖6-磷酸水平。或者，类似于其它利用己糖的激酶预测具有hsp 70特征性结构折叠的葡糖激酶本身或与其它E.大肠杆菌蛋白质，在稳定新合成的蛋白质中起作用。(C)出版社：Academic Press
A variety of stressful conditions, such as heat shock, ethanol, osmotic shock, glucose deprivation, and oxidative stress, are known to induce the synthesis of specific proteins. Here, we report the induction in Escherichia coli of a protein elicited in response to a hitherto unidentified stress condition, i.e., the overexpression of foreign proteins. The induced protein identified as glucokinase (EC 2.7.1.2) is produced at a level greater than or equal to 20-fold higher than the level in wild-type E. coli when foreign proteins are expressed under the control of the alkaline phosphatase (phoA) promoter. The bacterial glucokinase is shown to have a mass of approximately 47 kDa determined by a ''renaturation activity stain assay'' in situ following sodium dodecyl sulfate-polyacrylamide gel electrophoresis and exhibits a high specificity for the phosphorylation of glucose, The apparent K-m values for glucose and ATP for the enzyme are 0.15 and 0.50 mM, respectively, indicating that the E. coli enzyme is a low K-m glucose hexokinase. The enzyme cross-reacts with rabbit antisera raised against hexokinase hom higher eukaryotes, implicating some sequence similarity with mammalian hexokinases. Under normal conditions, E. coli glucokinase plays a minor role in glucose metabolism, However, under anabolic stress conditions, this glycolytic enzyme may be required to supplement levels of glucose 6-phosphate. Alternatively, glucokinase, which is predicted in analogy to other hexose-utilizing kinases to have structural folds characteristic of hsp 70, may itself, or in combination with other E. coli proteins, function in the stabilization of newly synthesized proteins. (C) 1995 Academic Press, Inc.