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Conformational and topological requirements of cell-permeable peptide function
1Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2363, USA.
Summary
Cell-permeable peptides use a carrier sequence for cell entry. Their helical structure in membrane environments is key, but not sufficient, for import, requiring specific side-chain arrangements for effective cellular delivery.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Biology
Background:
- Cell-permeable peptides facilitate synthetic peptide delivery into living cells.
- Import relies on an N-terminal carrier sequence, typically a hydrophobic signal peptide region.
Purpose of the Study:
- Investigate peptide conformation changes upon interaction with membrane mimetics.
- Determine topological requirements for efficient cell-permeable peptide function.
- Identify structural factors beyond helical propensity critical for cellular import.
Main Methods:
- Circular dichroism analysis to study peptide conformations.
- Interaction studies with sodium dodecyl sulfate (SDS) micelles and trifluoroethanol (TFE).
- Functional assays assessing cellular import efficiency with modified carrier sequences.
Main Results:
- Cell-permeable peptides adopt alpha-helical structures in SDS micelles and TFE.
- Helical structure formation is more potent in amphiphilic (SDS) than hydrophobic (TFE) environments.
- Carrier sequences at the C-terminus enable efficient cellular import.
- Retro carrier sequences lose translocating ability despite maintaining helical structure.
Conclusions:
- Amphiphilic membrane components may aid peptide import.
- Carrier sequence placement (N- or C-terminus) is flexible for efficient import.
- Helical propensity is necessary but insufficient; side-chain topology is crucial for cell-permeable peptide function.
- Findings enable more rational design of cell-permeable peptides.