The porinACj is an
α-helical porin that spans the mycolic
acid outer membrane of Gram-positive mycolate, Corynebacterium
jeikeium. Here, we report that a 40-amino acid, synthetic
peptide, pPorA corresponding to porin PorACj, inserts into the lipid
bilayers and forms well-defined pores. By electrical recordings, we
measured the single-channel properties that revealed the autonomous
assembly of large conductance ion-selective synthetic pores. Further,
we characterized the functional properties by blocking the peptide
pores by cyclodextrins of different charge and symmetry. We deduced
the subunit stoichiometry and putative structure of the pore by site-specific
chemical modification in single-channel electrical recordings and
gel electrophoresis. On the basis of these findings, we suggest that
this is a large functional uniform transmembrane pore built entirely
from short synthetic α-helical peptides. Accordingly, we propose
a model demonstrating structural assembly of large α-helix-based
peptide pores for understanding the action of antimicrobial peptides
and for the design of pores with applications in biotechnology.
Synthetic alpha-helix based pores for selective sensing of peptides have not been characterized previously. Here, we report a large transmembrane pore, pPorA formed from short synthetic alpha-helical peptides of tunable...
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