AcrD of Escherichia coli Is an Aminoglycoside Efflux Pump

AcrD, a transporter belonging to the resistance-nodulation-division family, was shown to participate in the efflux of aminoglycosides. Deletion of the acrD gene decreased the MICs of amikacin, gentamicin, neomycin, kanamycin, and tobramycin by a factor of two to eight, and ΔacrD cells accumulated higher levels of [(3)H]dihydrostreptomycin and [(3)H]gentamicin than did the parent strain.