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Characterizing Multidrug Efflux Systems in Acinetobacter baumannii Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System
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Drug-induced conformational changes in multidrug efflux transporter AcrB from Haemophilus influenzae

Vishakha Dastidar1, Weimin Mao, Olga Lomovskaya

  • 1Department of Chemistry and Biochemistry, 620 Parrington Oval, Norman, OK 73019, USA.

Journal of Bacteriology
|May 29, 2007
PubMed

Insights

Multidrug efflux pumps in gram-negative bacteria, like AcrB(HI) from Haemophilus influenzae, confer resistance. Substrate binding induces conformational changes in these transporters, impacting their function.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Gram-negative bacteria utilize Resistance-Nodulation-Cell Division (RND) superfamily transporters for intrinsic multidrug resistance.
  • Haemophilus influenzae produces the AcrB(HI) multidrug efflux transporter, which functions with AcrA(HI) and TolC(HI).

Purpose of the Study:

  • To investigate the in vivo dynamics and substrate-induced conformational changes of the AcrAB(HI) multidrug efflux transporter.
  • To determine if AcrAB(HI) expressed in Escherichia coli requires E. coli's TolC (TolC(EC)) for activity.

Main Methods:

  • Constructed single cysteine mutations in AcrB(HI) at substrate recognition sites.
  • Assessed in vivo accessibility of these cysteines to fluorescein-5-maleimide (FM) in the presence/absence of substrates, AcrA(HI), and TolC(EC).

Main Results:

  • AcrAB(HI) expressed in E. coli conferred multidrug resistance, dependent on TolC(EC).
  • The reactivity of specific cysteines with FM was altered by certain substrates, indicating substrate-specific conformational changes in AcrB(HI).

Conclusions:

  • Substrates induce conformational changes within the AcrB(HI) multidrug efflux transporter.
  • Understanding these dynamics is crucial for developing strategies to combat bacterial multidrug resistance.

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