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Updated: Jul 15, 2025
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Evolutionary Engineering a Larger Porin Using a Loop-to-Hairpin Mechanism
Rik Dhar1, Alexander M Bowman2, Brunojoel Hatungimana2
1Department of Molecular Biosciences, The University of Kansas, Lawrence, KS 66045, USA. Electronic address: https://twitter.com/Rik_Skywalker.
Journal of Molecular Biology
|September 28, 2023
Summary
Protein evolution can occur through novel mechanisms beyond gene duplication. This study provides the first experimental evidence for a loop to beta-hairpin transition in outer membrane beta-barrel evolution.
Area of Science:
- Protein evolution
- Structural biology
- Biochemistry
Background:
- Protein diversification is typically driven by genetic duplication, with repeating units like beta-hairpins evident in outer membrane beta-barrels.
- A computational study proposed an alternative evolutionary pathway involving a loop to beta-hairpin transition for increasing strand numbers in these barrels.
Purpose of the Study:
- To experimentally test the hypothesis that outer membrane beta-barrels can evolve through a loop to beta-hairpin transition.
- To investigate the structural and functional implications of this proposed evolutionary mechanism.
Main Methods:
- Construction of a chimeric protein by replacing loop L3 of a 16-stranded beta-barrel with the corresponding beta-hairpin region from an 18-stranded beta-barrel.
- Analysis of the chimeric protein's stability and structural characteristics.
Main Results:
- The created chimeric protein was found to be stable.
- The chimeric protein exhibited characteristics indicative of an increased strand number, supporting the proposed transition.
Conclusions:
- This research provides the first experimental validation for the loop to beta-hairpin transition as a mechanism in outer membrane beta-barrel evolution.
- The findings expand our understanding of protein diversification beyond traditional gene duplication models.
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