Diversity in structural consequences of MexZ mutations in Pseudomonas aeruginosa

Area of Science:

• Microbiology
• Structural Biology
• Computational Biology

Background:

• Pseudomonas aeruginosa is a primary cause of morbidity and mortality in cystic fibrosis (CF) patients.
• High antibiotic resistance in P. aeruginosa stems from its outer membrane permeability and multidrug resistance (MDR) efflux systems.
• MexZ, the negative regulator of the MexXY efflux pump, is frequently mutated in P. aeruginosa from CF lungs, highlighting its role in MDR.

Purpose of the Study:

• To investigate the structural consequences of specific MexZ mutations (L25P, G46V, P151L, S202F) in P. aeruginosa.
• To elucidate how these mutations affect MexZ's function, particularly its interaction with DNA.

Main Methods:

• Utilized molecular modeling and molecular dynamics simulations based on the known MexZ structure.
• Analyzed the impact of four distinct MexZ mutations on protein structure and dynamics.

Main Results:

• The G46V mutation was identified as completely abolishing MexZ's DNA binding ability.
• This critical G46V mutation is located within an evolutionarily conserved region of MexZ.
• Significant fluctuations were observed in the DNA-binding domain and Helix4, indicating altered protein dynamics.

Conclusions:

• Structural analysis reveals diverse consequences of MexZ mutations in P. aeruginosa.
• The G46V mutation's disruption of DNA binding is a key mechanism contributing to antibiotic resistance in CF.
• These findings provide insights into the molecular basis of MDR in P. aeruginosa and potential therapeutic targets.