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PMID:15743938

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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

Significance

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


See also

References

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