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Directed Protein Packaging within Outer Membrane Vesicles from Escherichia coli: Design, Production and Purification
Published on: November 16, 2016
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Distinctive Roles for Periplasmic Proteases in the Maintenance of Essential Outer Membrane Protein Assembly
Garner R Soltes1, Nicholas R Martin1, Eunhae Park1
1Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA.
Journal of Bacteriology
|August 9, 2017
Summary
Three periplasmic proteases, DegP, BepA, and YcaL, act as quality control factors, degrading outer membrane proteins (OMPs) with assembly defects at distinct stages of the biogenesis pathway in Escherichia coli.
Area of Science:
- Microbiology
- Molecular Biology
- Protein Folding
Background:
- Outer membrane protein (OMP) biogenesis is crucial for Gram-negative bacteria, facilitated by the β-barrel assembly machine (Bam) complex.
- Periplasmic chaperones and proteases ensure the integrity of OMP trafficking, but their substrate recognition mechanisms during assembly defects remain unclear.
Purpose of the Study:
- To investigate how periplasmic proteases recognize and degrade OMP substrates with compromised assembly.
- To determine if different proteases target OMP substrates at distinct stages of the assembly pathway.
Main Methods:
- Utilized well-defined, assembly-defective mutants of the lipopolysaccharide translocon LptD in Escherichia coli.
- Analyzed the degradation roles of periplasmic proteases DegP, BepA, and the outer membrane lipoprotein YcaL in response to specific LptD assembly defects.
Main Results:
- DegP degrades LptD mutants with early assembly defects, preventing Bam complex interaction.
- BepA targets LptD mutants that have engaged Bam and formed nearly complete barrels.
- YcaL degrades LptD mutants engaged with Bam but stalled at an earlier stage than BepA targets.
Conclusions:
- Multiple periplasmic proteases surveil OMP assembly at distinct stages, ensuring pathway integrity.
- These proteases act as crucial quality control factors, clearing misfolded OMPs and maintaining the bacterial permeability barrier.
- Understanding these mechanisms provides insights into antibiotic resistance in Gram-negative bacteria.
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