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Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking
Published on: December 17, 2013
BamE modulates the Escherichia coli beta-barrel assembly machine component BamA
Nathan W Rigel1, Jaclyn Schwalm, Dante P Ricci
1Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA.
Journal of Bacteriology
|December 20, 2011
Summary
Outer membrane protein assembly in bacteria relies on the Bam complex. The study reveals BamE is crucial for stabilizing the BamA protein
Area of Science:
- Microbiology
- Bacterial Cell Biology
- Protein Assembly
Background:
- Outer membrane (OM) biogenesis is vital for Gram-negative bacteria.
- The Bam complex, comprising BamA, BamD, BamB, BamC, and BamE, assembles outer membrane proteins (OMPs).
- BamC and BamE stabilize the interaction between BamA and BamD.
Purpose of the Study:
- To elucidate the interplay between BamA and the BamCDE subcomplex.
- To investigate the specific role of BamE in outer membrane protein assembly.
Main Methods:
- Comprehensive genetic analysis was employed.
- Synthetic phenotypes were analyzed in various mutant backgrounds (e.g., ΔbamE, ΔbamC).
- Proteinase K sensitivity assays were used to assess BamA conformational states.
Main Results:
- Combining a ΔbamE allele with mutations in other OMP assembly factors caused severe synthetic phenotypes, highlighting BamE's critical function.
- Synthetic phenotypes were less severe in a ΔbamC background, indicating non-overlapping functions of BamC and BamE.
- In ΔbamE mutants, BamA was degraded upon proteinase K treatment, unlike in wild-type cells where BamA remained sensitive.
Conclusions:
- BamE plays a unique and critical role in outer membrane protein assembly.
- BamE likely modulates the conformation of BamA, potentially via interactions with BamD.
- These findings provide new insights into the regulatory mechanisms of the Bam complex.
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