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  • Title: The acrAB locus is involved in modulating intracellular acetyl coenzyme A levels in a strain of Escherichia coli CM2555 expressing the chloramphenicol acetyltransferase (cat) gene.
    Author: Potrykus J, Wegrzyn G.
    Journal: Arch Microbiol; 2003 Nov; 180(5):362-6. PubMed ID: 14614545.
    Abstract:
    Recently, an Escherichia coli CM2555 strain was described as sensitive to chloramphenicol when expressing the chloramphenicol resistance gene (cat) from a multicopy plasmid. This sensitivity was linked to dysfunction of the acrA gene, which encodes a component of the AcrAB-TolC multidrug efflux pump. Preliminary data indicate that the sensitivity phenotype might be due to a decline in intracellular acetyl coenzyme A concentration accompanying the reaction catalyzed by chloramphenicol acetyltransferase, the cat-encoded resistance protein. Here, we demonstrate that the acrA dysfunction is the factor impairing the intracellular acetyl coenzyme A levels in the cat-expressing CM2555 strain. This effect might be alleviated by the interplay of proteins constituting two homologous efflux systems: AcrAB-TolC and AcrEF-TolC. However, our results show also that this is a genetic background-specific phenomenon, as the decrease in acetyl coenzyme A level is not evident in a cat-bearing DeltaacrAB derivative of the commonly used strain C600.
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