Cryo-EM structure of the Pseudomonas aeruginosa MexY multidrug efflux pump
William D Gregor1, Rakesh Maharjan1, Zhemin Zhang1
1Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.
Abstract:
Pseudomonas aeruginosa, a Gram-negative pathogen, has emerged as one of the most highly antibiotic-resistant bacteria worldwide and subsequently has become a leading cause of healthcare-associated, life-threatening infections. P. aeruginosa multidrug efflux Y (MexY) is an efflux pump that belongs to the resistance-nodulation-cell division (RND) superfamily. It is a major determinant for resistance to aminoglycosides in this opportunistic pathogen. However, the detailed molecular mechanisms involved in aminoglycoside recognition and extrusion by MexY have not been elucidated. Here, we report the cryo-electron microscopy structure of MexY to a resolution of 3.63 Å. The structure directly indicates two plausible pathways for drug export. It also suggests that MexY is capable of picking up antibiotics via the ceiling of the central cavity formed by the MexY trimer. Molecular dynamics simulations depict that MexY is able to use a tunnel connecting the central cavity to the funnel of the trimer to export its substrates.
Importance:
Here, we report the cryo-electron microscopy structure of the MexY multidrug efflux pump, posing the possibility that this pump is capable of capturing antibiotics from both the central cavity and the periplasmic cleft of the pump. The results indicate that MexY may utilize charged residues to bind and export drugs, mediating resistance to these antibiotics.
Insights
Researchers visualized the Pseudomonas aeruginosa multidrug efflux Y (MexY) pump structure. This reveals how MexY captures and exports antibiotics, offering insights into bacterial drug resistance mechanisms.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Pseudomonas aeruginosa is a major cause of difficult-to-treat infections due to high antibiotic resistance.
- The multidrug efflux Y (MexY) pump, part of the RND superfamily, is crucial for aminoglycoside resistance in P. aeruginosa.
- The precise molecular mechanisms of MexY's drug recognition and export remain unclear.
Purpose of the Study:
- To determine the high-resolution structure of the MexY multidrug efflux pump.
- To elucidate the molecular mechanisms underlying antibiotic recognition and extrusion by MexY.
- To investigate potential drug binding and export pathways within the MexY structure.
Main Methods:
- Cryo-electron microscopy (cryo-EM) was used to obtain the MexY structure at 3.63 Å resolution.
- Molecular dynamics (MD) simulations were employed to analyze drug transport pathways.
Main Results:
- The cryo-EM structure revealed two potential drug export pathways.
- The MexY structure suggests antibiotic uptake via the ceiling of its central cavity.
- MD simulations indicated MexY utilizes an internal tunnel for substrate export.
Conclusions:
- The MexY structure provides a molecular basis for its function in antibiotic resistance.
- MexY may capture antibiotics from both the central cavity and periplasmic cleft.
- Charged residues likely play a role in MexY's drug binding and export mechanisms.
