PMID:15743938

Citation	Aires, JR and Nikaido, H (2005) Aminoglycosides are captured from both periplasm and cytoplasm by the AcrD multidrug efflux transporter of Escherichia coli. J. Bacteriol. 187:1923-9
Abstract	To understand better the mechanisms of resistance-nodulation-division (RND)-type multidrug efflux pumps, we examined the Escherichia coli AcrD pump, whose typical substrates, aminoglycosides, are not expected to diffuse spontaneously across the lipid bilayer. The hexahistidine-tagged AcrD protein was purified and reconstituted into unilamellar proteoliposomes. Its activity was measured by the proton flux accompanying substrate transport. When the interior of the proteoliposomes was acidified, the addition of aminoglycosides to the external medium stimulated proton efflux and the intravesicular accumulation of radiolabeled gentamicin, suggesting that aminoglycosides can be captured and transported from the external medium in this system (corresponding to cytosol). This activity required the presence of AcrA within the proteoliposomes. Interestingly, the increase in proton efflux also occurred when aminoglycosides were present only in the intravesicular space. This result suggested that AcrD can also capture aminoglycosides from the periplasm to extrude them into the medium in intact cells, acting as a "periplasmic vacuum cleaner."
Links	PubMed PMC1064028 Online version:10.1128/JB.187.6.1923-1929.2005
Keywords	Acids/metabolism; Aminoglycosides/metabolism; Anti-Bacterial Agents/pharmacokinetics; Cytoplasm/metabolism; Cytoplasmic Vesicles/metabolism; Drug Resistance, Multiple, Bacterial/physiology; Escherichia coli K12/metabolism; Escherichia coli Proteins/metabolism; Gentamicins/pharmacokinetics; Lipoproteins/metabolism; Membrane Transport Proteins/metabolism; Periplasm/metabolism; Proteolipids/metabolism; Streptomycin/pharmacokinetics; Tritium/diagnostic use
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOLI:TOLC	located_in	GO:0098567: periplasmic side of plasma membrane	ECO:0005547: biological system reconstruction evidence based on inference from background scientific knowledge used in manual assertion		C		Seeded From UniProt	complete
ECOLI:TOLC	located_in	GO:1990281: efflux pump complex	ECO:0005547: biological system reconstruction evidence based on inference from background scientific knowledge used in manual assertion		C		Seeded From UniProt	complete
ECOLI:TOLC	involved_in	GO:0140330: xenobiotic detoxification by transmembrane export across the cell outer membrane	ECO:0005547: biological system reconstruction evidence based on inference from background scientific knowledge used in manual assertion		P		Seeded From UniProt	complete
ECOLI:ACRA	located_in	GO:0098567: periplasmic side of plasma membrane	ECO:0005547: biological system reconstruction evidence based on inference from background scientific knowledge used in manual assertion		C		Seeded From UniProt	complete
ECOLI:ACRA	located_in	GO:1990281: efflux pump complex	ECO:0005547: biological system reconstruction evidence based on inference from background scientific knowledge used in manual assertion		C		Seeded From UniProt	complete
ECOLI:ACRA	involved_in	GO:0140330: xenobiotic detoxification by transmembrane export across the cell outer membrane	ECO:0005547: biological system reconstruction evidence based on inference from background scientific knowledge used in manual assertion		P		Seeded From UniProt	complete
ECOLI:ACRD	acts_upstream_of_or_within	GO:0042908: xenobiotic transport	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
ECOLI:ACRD	located_in	GO:0016020: membrane	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete
ECOLI:ACRD	located_in	GO:0098567: periplasmic side of plasma membrane	ECO:0005547: biological system reconstruction evidence based on inference from background scientific knowledge used in manual assertion		C		Seeded From UniProt	complete
ECOLI:ACRD	located_in	GO:1990281: efflux pump complex	ECO:0005547: biological system reconstruction evidence based on inference from background scientific knowledge used in manual assertion		C		Seeded From UniProt	complete
ECOLI:ACRD	involved_in	GO:0140330: xenobiotic detoxification by transmembrane export across the cell outer membrane	ECO:0005547: biological system reconstruction evidence based on inference from background scientific knowledge used in manual assertion		P		Seeded From UniProt	complete

References

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