| Research Abstract |
The chromosomal cephalosporinase gene of gram-negative bacteria cloned on a small plasmid in Escherichia coli is expressed rather poorly.
Expression of this cephalosporinase gene on the recombinant plasmid was strikingly improved by mutation of a chromosomal gene of E.coli, designated,ded, which map on chromosomal gene of E.coli genetic map. The host mutation did not affect chromosomal beta-lactamase activity of E.coli, but it caused more than 50-fold stimulation of cephalosporinase production in the strains carrying cloned plasmid. A deletion derivative of cloned plasmid, which had lost a DNA sequence necessary for induction of the cephalosporinase, was unaffected on its expression by the deb mutation.
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