Gene

Chlorpromazine

Acinetobacter baumannii

Staphylococcus aureus

Pseudomonas aeruginosa

Bacteria

Biology

Drug resistance

Multidrug Resistance-Associated Proteins

Biochemistry

Genetics

Transporter

Klebsiella pneumoniae

Salmonella enterica

Amitriptyline

Antibiotics

Microbiology

Escherichia coli

Pharmacology

Enterococcus faecium

Medicine

Chemistry

ATP-binding cassette transporter

Multiple drug resistance

Efflux

mBio

Efflux pumps of the resistance nodulation-cell division (RND) superfamily are major contributors to multidrug resistance for most of the Gram-negative ESKAPE ( Enterococcus faecium , Staphylococcus aureus , Klebsiella pneumoniae , Acinetobacter baumannii , Pseudomonas aeruginosa , and Enterobacter species) pathogens. The development of inhibitors of these pumps would be highly desirable; however, several issues have thus far hindered all efforts at designing new efflux inhibitory compounds devoid of adverse effects. An alternative route to de novo design relies on the use of marketed drugs, for which side effects on human health have been already assessed. In this work, we provide experimental evidence that the antipsychotic drugs chlorpromazine and amitriptyline are inhibitors of the AcrB transporter, the engine of the major RND efflux pumps in Escherichia coli and Salmonella enterica serovar Typhimurium. Furthermore, in silico calculations have provided a molecular-level picture of the inhibition mechanism, allowing rationalization of experimental data and paving the way for similar studies with other classes of marketed compounds.

Chlorpromazine and Amitriptyline Are Substrates and Inhibitors of the AcrB Multidrug Efflux Pump