Response dynamics of 26-, 34-, 39-, 54-, and 80-kDa proteases in induced cultures of recombinant Escherichia coli.
Several researchers have demonstrated that the presence of a heterologous protein in recombinant Escherichia coli elicits a response similar to the heat-shock response, which includes enhanced protease expression. The present work detects, quantifies, and characterizes intracellular protease activity in E. coli that are "shocked" by the induction of a recombinant protein, CAT, which is an endogenous protein in some E. coli strains. A novel, sodium dodecyl sulfate gelatin poly-acrylamide gel electrophoresis (SDS-GPAGE) method is used to detect, quantify, and characterize the presence of these proteases. A hypothesis is proposed which links the amplified protease activity to a temporary depletion of specific amino acid pools, and a stringent-like stress response.
Harcum
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Center for Agricultural Biotechnology, and Department of Chemical Engineering, University of Maryland, College Park, Maryland 20742, USA.
Bentley
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WE