Control and DNA Structure of the ampC β-Lactamase Gene of Escherichia coli
Escherichia coli K-12 is coding for a β-lactamase which hydrolyzes the β-lactam ring of both cephalosporins and penicillins including ampicillin. Its structural gene, ampC, has been mapped to 93.8 min on the E. coli chromosome (Burman et al., 1973; Grundström et al., 1980). The level of ampC β-lactamase is stric — ly proportional to the gene dosage, and to the ampicillin resistance (Normark et al., 1977) These features enabled us to directly select for ColEl ampC hybrid clones within the collection of ColEl hybrids prepared by Clarke and Carbon (Clarke and Carbon, 1976; Edlund et al., 1979). One ColEl ampC hybrid plasmid was physically mapped and the location of ampC within this plasmid was deduced by subcloning (Grundstrom et al., 1980). We could thereby demonstrate that the ampC gene was present on a 1,370 bp DNA segment. by selecting for various degrees of ampicillin resistance a number of IS. coli mutants have been i-solated that hyperproduce the ampC β-lactamase due to mutations in ampA, a control sequence region for ampC (Grundström et al., 1980).
KeywordsAmino Acid Sequence Homology Control Sequence Region Swedish Natural Science Research Council Dyad Symmetry ampC Gene
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