Role of AmpR in the High Expression of the Plasmid-Encoded AmpC β-Lactamase CFE-1

Ryuichi Nakano; Akiyo Nakano; Hisakazu Yano; Ryoichi Okamoto

doi:10.1128/mSphere.00192-17

Role of AmpR in the High Expression of the Plasmid-Encoded AmpC β-Lactamase CFE-1

mSphere. 2017 Aug 9;2(4):e00192-17. doi: 10.1128/mSphere.00192-17. eCollection 2017 Jul-Aug.

Authors

Ryuichi Nakano¹, Akiyo Nakano¹, Hisakazu Yano¹, Ryoichi Okamoto²

Affiliations

¹ Department of Microbiology and Infectious Diseases, Nara Medical University, Kashihara, Nara, Japan.
² Department of Microbiology, Kitasato University School of Medicine, Sagamihara, Kanagawa, 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.

Keywords: AmpR; antibiotic resistance; plasmid-encoded AmpC β-lactamase; regulation.