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Updated: Feb 24, 2026

Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance
Published on: May 2, 2018
Role of AmpR in the High Expression of the Plasmid-Encoded AmpC β-Lactamase CFE-1
Ryuichi Nakano1, Akiyo Nakano1, Hisakazu Yano1
1Department of Microbiology and Infectious Diseases, Nara Medical University, Kashihara, Nara, Japan.
Abstract:
CFE-1 is a unique plasmid-encoded AmpC β-lactamase with the regulator gene ampR. It imparts high resistance to most cephalosporins with constitutive high-level β-lactamase activity. Here, the β-lactamase activities and expression levels of ampC with or without ampR were investigated. Results suggested that the resistance of CFE-1 to cephalosporins is caused by a substitution in AmpR, in which the Asp at position 135 is modified to Ala to allow the constitutive high-level expression (derepression) of ampC.
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