Progress on AmpC hyperproduction in Escherichia coli / 医学研究生学报

ABSTRACT

The ampC ?-lactamases gene in Escherichia coli(E.coli) is different from other Gram-negative bacteria.E.coli contains a chromosomal ampC gene which has a weak promoter as well as a transcriptional attenuator.The promoter of the ampC gene in E.coli is part of the preceding frd operon,the attenuator of the ampC gene is a transcription terminator for the frd operon.The ampC regulatory gene,ampR,is absent.Strains carrying the wild-type gene produce a low basal amount of AmpC.Studies on the molecular basis of AmpC overproduction in E.coli have shown that some hyperproducers contain mutation in the promoter region and/or attenautor and/or ampC-coding region of ampC,while others contain more than one copy of ampC.Acquisition of a stronger promoter or insertion of an insertion element containing promoter sequences or regulatory gene ampR has also been proposed as the molecular basis of hyperproduction of AmpC in some E.coli strains.Plasmid-mediated AmpC ?-lactamases have been discovered frequently in E.coli strains.This is another reason for hyperproduction of AmpC ?-lactamases.