Experimental Evolution of Escherichia coli K-12 in the Presence of Proton Motive Force (PMF) Uncoupler Carbonyl Cyanide m-Chlorophenylhydrazone Selects for Mutations Affecting PMF-Driven Drug Efflux Pumps.

ABSTRACT: Experimental evolution of Escherichia coli K-12 with benzoate, a partial uncoupler of the proton motive force (PMF), selects for mutations that decrease antibiotic resistance. We conducted experimental evolution in the presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP), a strong uncoupler. Cultures were serially diluted daily 1:100 in LBK medium containing 20 to 150 µM CCCP buffered at pH 6.5 or at pH 8.0. After 1,000 generations, the populations tolerated up to 150 µM CCCP. Sequenced isolates had mutations in mprA (emrR), which downregulates the EmrAB-TolC pump that exports CCCP. A mprA::kanR deletion conferred growth at 60 μM CCCP, though not at the higher levels resisted by evolved strains (150 µM). Some mprA mutant strains also had point mutations affecting emrA, but deletion

SUBMITTER: Griffith JM 

PROVIDER: S-EPMC6384104 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature