Production of an E. coli Toxin Protein; Colicin A in E. coli Using an Inducible System

The ultimate aim of biochemistry is to decipher how events occur inside of living cells or organisms. The living cell must also be regarded as the ideal model system for any biochemical application, as most physiological targets are found inside living cells. The cell envelope of the Gram-negative bacterium Escherichia coli is a complex structure and many of the proteins found in the bacterial envelope are involved in import mechanisms. A variety of bacterial toxins have taken advantage of some of these envelope proteins to enter the bacteria. Pore-forming toxins present the important challenge of the translocation process, and the study of the membrane insertion mechanism of pore-forming colicins has also become a very important subject. How these proteins pass through or integrate into membranes is still one of the fundamental unsolved problems in biochemistry. Colicins are plasmid-encoded toxin proteins produced by immune E. coli that are active against sensitive E. coli and closely related cells. Their toxic activities are of various types; some colicins form ion ∗Corresponding author