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Updated: Aug 19, 2026
Expression, Detergent Solubilization, and Purification of a Membrane Transporter, the MexB Multidrug Resistance Protein
Published on: December 3, 2010
Multidrug transporter MexB of Pseudomonas aeruginosa: overexpression, purification, and initial structural
Vladislav Mokhonov1, Ekaterina Mokhonova, Eisaku Yoshihara
1Department of Molecular Life Science, Tokai University, School of Medicine, 143 Shimokasuya, Isehara 259-1193, Japan.
Abstract:
Structural and functional characterization of the multidrug transporter, MexB, of Pseudomonas aeruginosa is significantly restricted due to a low yield of approximately 0.1 mg/L of culture from natural sources. To facilitate structural studies of this medically important transporter protein, we developed a large-scale system for expression of the genetically engineered recombinant, MexB, in the Escherichia coli cell. Using the system, the eventual yield of MexB attained was about 10mg/L of culture. The optimized purification protocol in the presence of dodecyl beta-D-maltoside allowed isolation of highly homogeneous MexB. The oligomeric state of the protein in detergent solution has been characterized to verify that the native state of the purified protein has been preserved. The molecular mass of the protein-detergent complex was found to be 380-450kDa. The MexB-dodecyl beta-d-maltoside mass ratio was determined to be 1.8 +/- 0.05. Taking into account the monomeric MexB molecular mass deduced from its amino acid sequence (112.8 kDa), we concluded that the purified MexB exists as the homotrimer in the surfactant solution. Circular dichroism analysis of MexB showed dominance of the alpha-helix structures. High yield, homogeneity, and stability of MexB position it as a good candidate for structural and functional characterization.
Insights
Researchers developed a large-scale system to produce the MexB multidrug transporter from Pseudomonas aeruginosa in Escherichia coli, achieving higher yields for structural studies. This optimized production and purification method yields stable, homogeneous MexB, suitable for further characterization.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- The multidrug transporter MexB from Pseudomonas aeruginosa is crucial for antibiotic resistance.
- Low natural yields of MexB hinder structural and functional studies, limiting understanding of its mechanism.
Purpose of the Study:
- To develop a scalable system for high-yield recombinant MexB expression in Escherichia coli.
- To establish an optimized purification protocol for homogeneous MexB suitable for structural analysis.
Main Methods:
- Genetically engineered recombinant MexB expression in Escherichia coli.
- Large-scale culture and optimized purification using dodecyl beta-D-maltoside.
- Oligomeric state determination via molecular mass and mass ratio analysis.
- Circular dichroism spectroscopy for secondary structure analysis.
Main Results:
- Achieved a MexB yield of approximately 10 mg/L, a significant increase from natural sources.
- Isolated highly homogeneous MexB protein, preserving its native state.
- Determined that purified MexB exists as a homotrimer in dodecyl beta-D-maltoside solution.
- Circular dichroism confirmed a high alpha-helix content in MexB structure.
Conclusions:
- The developed large-scale expression and purification system provides high-yield, homogeneous, and stable MexB.
- The purified MexB is well-suited for detailed structural and functional characterization.
- This advancement facilitates research into MexB's role in multidrug resistance and potential therapeutic targeting.
