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A monodisperse transmembrane α-helical peptide barrel

Abstract

The fabrication of monodisperse transmembrane barrels formed from short synthetic peptides has not been demonstrated previously. This is in part because of the complexity of the interactions between peptides and lipids within the hydrophobic environment of a membrane. Here we report the formation of a transmembrane pore through the self-assembly of 35 amino acid α-helical peptides. The design of the peptides is based on the C-terminal D4 domain of the Escherichia coli polysaccharide transporter Wza. By using single-channel current recording, we define discrete assembly intermediates and show that the pore is most probably a helix barrel that contains eight D4 peptides arranged in parallel. We also show that the peptide pore is functional and capable of conducting ions and binding blockers. Such α-helix barrels engineered from peptides could find applications in nanopore technologies such as single-molecule sensing and nucleic-acid sequencing.

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Figure 1: Structure of E. coli Wza, peptide design and electrical properties of the cWza pore.
Figure 2: Electrical properties of mutant cWza pores.
Figure 3: Interaction of cWza peptide pores with cationic CDs.
Figure 4: Orientation and stoichiometry of the cWza-Y373C pore.
Figure 5: CD-templated barrel and its electrical properties.
Figure 6: Model for membrane insertion and pore formation by cWza peptides.

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Acknowledgements

The authors acknowledge a Biotechnology and Biological Sciences Research Council grant (BB/J009784/1) and the European Research Council (340764) for financial support. D.N.W. holds a Royal Society Wolfson Research Merit Award.

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K.R.M. performed and analysed the current recordings. A.N. synthesized peptides and determined their biophysical properties. L.K. produced the Wza protein and synthesized the CD derivatives. A.N. and A.R.T. performed the molecular modelling. A.N. and R.B.S. performed the molecular dynamics simulations. K.R.M., A.N., D.N.W. and H.B. designed experiments and wrote the paper.

Corresponding authors

Correspondence to Derek N. Woolfson or Hagan Bayley.

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The authors declare no competing financial interests.

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Mahendran, K., Niitsu, A., Kong, L. et al. A monodisperse transmembrane α-helical peptide barrel. Nature Chem 9, 411–419 (2017). https://doi.org/10.1038/nchem.2647

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