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From Constructs to Crystals – Towards Structure Determination of β-barrel Outer Membrane Proteins
Published on: July 4, 2016
Assembly factor Omp85 recognizes its outer membrane protein substrates by a species-specific C-terminal motif
Viviane Robert1, Elena B Volokhina, Freya Senf
1Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands.
Plos Biology
|November 9, 2006
Summary
Outer-membrane protein assembly relies on Omp85, which recognizes a C-terminal signature sequence on substrate proteins. This mechanism explains species-specific assembly and allows heterologous protein integration.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Integral beta-barrel proteins are crucial components of outer membranes in various cellular compartments.
- Omp85 is an evolutionarily conserved protein essential for the assembly of these beta-barrel proteins.
Purpose of the Study:
- To elucidate the molecular mechanism of Omp85-mediated protein assembly.
- To investigate the role of specific protein sequences in substrate recognition by Omp85.
Main Methods:
- Production and in vitro refolding of Omp85 from Escherichia coli.
- Lipid-bilayer experiments to study Omp85 channel formation and interaction with substrate proteins.
- Analysis of species-specific interactions using outer membrane proteins (OMPs) from different bacterial species.
Main Results:
- Omp85 forms channels in lipid bilayers, and its properties are modulated by unfolded OMPs and synthetic peptides.
- Species specificity was observed in Omp85-substrate interactions, explaining inefficient assembly of Neisseria OMPs in E. coli.
- Adapting the C-terminal signature sequence of Neisseria porin PorA enabled its assembly into E. coli outer membranes.
Conclusions:
- The Omp85 assembly machinery recognizes outer membrane proteins via their C-terminal signature sequence.
- This recognition mechanism dictates species specificity in protein assembly.
- The findings provide a basis for engineering heterologous protein assembly in bacterial outer membranes.
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