A METHOD OF CREATING AN EXPRESSION PLASMID

摘要

Novel plasmidic expression vehicles and methods of using them in the production of useful polypeptides by recombinant bacteria are described. The plasmids employ a tryptophan promoter-operator system from which the attenuator region ordinarily present has been deleted. Bacteria containing the plasmids can accordingly be repressed by the addition of tryptophan against expression of desired polypeptides coded for by inserted genes while they are grown to levels suitable for industrial-scale production. Additive tryptophan may then be withdrawn, essentially derepressing the pathway and permitting efficient production of the desired product in high yield.