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TtOmp85, a β-barrel assembly protein, functions by barrel augmentation
Luisa Estrada Mallarino1, Enguo Fan, Meike Odermatt
1Department of Biology, University of Konstanz , Universitätsstraße 10, 78457 Konstanz, Germany.
Biochemistry
|December 25, 2014
Summary
Outer membrane proteins are inserted by Omp85/BamA family proteins. TtoA protein insertion into liposomes by an Omp85 homologue suggests a compound channel model for protein transport.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Outer membrane proteins are essential for Gram-negative bacteria and their derived organelles.
- The Omp85/BamA protein family facilitates the insertion of proteins into the outer membrane.
Purpose of the Study:
- To investigate the insertion and folding mechanism of the outer membrane protein TtoA.
- To elucidate the role of Omp85 homologues in protein transport across membranes.
Main Methods:
- Studied the insertion and folding of TtoA into liposomes mediated by an Omp85 homologue.
- Measured channel conductance of Omp85 in black lipid membranes with and without TtoA peptides.
Main Results:
- An eight-stranded outer membrane protein, TtoA, was successfully inserted and folded into liposomes by an Omp85 homologue.
- Compound channels formed by Omp85 and TtoA peptides exhibited higher conductance than Omp85 alone.
- Data support a model of sequential augmentation of the Omp85 beta-barrel by incoming outer membrane proteins.
Conclusions:
- Omp85 homologues facilitate the insertion of outer membrane proteins like TtoA.
- A compound channel model involving sequential beta-strand augmentation is proposed for outer membrane protein biogenesis.
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