RND efflux pumps: structural information translated into function and inhibition mechanisms

Area of Science:

• Microbiology
• Structural Biology
• Biochemistry

Background:

• Efflux pumps, particularly the Resistance Nodulation Division (RND) superfamily, are critical for intrinsic and acquired antibiotic resistance in Gram-negative pathogens.
• These pumps are a primary cause of multi-drug resistance (MDR) in bacteria, posing significant challenges to infectious disease treatment.
• The AcrAB-TolC efflux pump, featuring the RND transporter AcrB, is a major focus due to its role in expelling diverse noxious agents.

Purpose of the Study:

• To review recent experimental and computational studies on the functional mechanisms of RND efflux pumps.
• To highlight the central role of AcrB in bacterial multi-drug resistance.
• To summarize advances in understanding AcrB's interactions with substrates, inhibitors, and its assembly into a functional pump.

Main Methods:

• Review of experimental data from structural biology and biochemical assays.
• Analysis of computational studies, including molecular dynamics simulations.
• Synthesis of findings on AcrB's dynamics, proton translocation, and protein-protein interactions.

Main Results:

• Detailed insights into the dynamical interactions between AcrB and its substrates/inhibitors.
• Elucidation of proton translocation mechanisms driving substrate efflux.
• Understanding of AcrB's assembly with other components to form the complete AcrAB-TolC efflux system.

Conclusions:

• AcrB is a crucial component of the AcrAB-TolC efflux pump, central to multi-drug resistance in Gram-negative bacteria.
• Recent research has significantly advanced our understanding of AcrB's structure-function relationship and mechanism of action.
• Further studies on AcrB and related RND efflux pumps are vital for developing novel strategies to combat antibiotic resistance.