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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
PubMed
Summary
This summary is machine-generated.

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.

Keywords:
loop-to-hairpinmolecular evolutionneisserial porinouter membrane proteinsβ-barrel

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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.