Efflux of chloramphenicol by the Cm1A1 protein

The cmlA1 gene cassette contains the cmlA1 gene, that confers resistance to chloramphenicol, as well as a promoter and translational attenuation signals, and expression of cmlA1 is inducible by low concentrations of chloramphenicol. The CmlA1 protein encoded by cmlA1 was localised in the inner membrane. Active efflux of chloramphenicol, additional to the endogenous efflux from Escherichia coli cells, was observed when the cmlA1 gene was present and the production of CmlA1 had been preinduced with subinhibitory concentrations of chloramphenicol. Both endogenous and CmlA1-mediated export of chloramphenicol was driven by the proton-motive force. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.