Glucokinase of escherichia-coli: Induction in response to the stress of overexpressing foreign proteins

Krishan K. Arora, Peter L. Pedersen

Research output: Contribution to journalArticlepeer-review

Abstract

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 ≥ 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 Km 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 Km 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.

Original languageEnglish (US)
Pages (from-to)574-578
Number of pages5
JournalArchives of Biochemistry and Biophysics
Volume319
Issue number2
DOIs
StatePublished - Jun 10 1995

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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