Periplasmic protein quality control at atomic level in live cells.

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• The periplasm is vital for gram-negative bacteria, supporting functions like nutrient uptake, cell wall metabolism, antibiotic resistance, and virulence.
• Effective protein quality control within the periplasm is essential for bacterial survival and fitness.
• The periplasm's confined space presents challenges for detailed mechanistic studies of its complex processes.

Purpose of the Study:

• To investigate the mechanism of periplasmic protein quality control in live bacteria.
• To elucidate the roles of proteases Prc and DegP in degrading the metallo-β-lactamase NDM-1 under zinc-deficient conditions.

Main Methods:

• Utilized in-cell NMR spectroscopy to achieve high-resolution analysis within the periplasmic compartment.
• Studied the destabilization and degradation of NDM-1 under zinc starvation to probe quality control pathways.

Main Results:

• Demonstrated that zinc starvation destabilizes the native structure of NDM-1, marking it for degradation.
• Showed that the protease Prc specifically targets membrane-bound NDM-1 at distinct residues and secondary structure elements.
• Revealed that the protease DegP further processes peptide fragments generated by Prc.

Conclusions:

• Disclosed the coordinated action of Prc and DegP in periplasmic protein degradation at atomic resolution in living cells.
• Highlighted the importance of protease concert in maintaining protein homeostasis within the bacterial periplasm.
• Provided novel insights into bacterial survival mechanisms under nutrient stress through protein quality control.