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Membrane interaction and cellular internalization of penetratin peptides
Bart Christiaens1, Johan Grooten, Michael Reusens
1Department of Biochemistry of the Ghent University, Belgium. bartchrist@hotmail.com
European Journal of Biochemistry
|March 11, 2004
Summary
Positively charged residues in penetratin are crucial for initial vesicle interaction, while Trp48 specifically aids endocytosis-independent cellular uptake. Variants showed altered membrane insertion but maintained low toxicity.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Penetratin, a peptide derived from the Antennapedia homeodomain, facilitates cellular internalization of molecules.
- Understanding its membrane translocation mechanism is key for developing effective drug delivery vectors.
Purpose of the Study:
- To investigate the roles of charged and tryptophan residues in penetratin's membrane interaction and cellular uptake.
- To synthesize and characterize novel penetratin variants to elucidate its translocation mechanism.
Main Methods:
- Synthesis of penetratin variants with specific amino acid substitutions (Lys/Arg to Ala, Trp to Phe).
- Utilized tryptophan fluorescence titrations and quenching experiments to study peptide-lipid interactions.
- Assessed membrane interaction using calcein leakage and vesicle aggregation assays.
- Evaluated cellular internalization in MDCK cells via flow cytometry and endocytosis-independent uptake studies.
Main Results:
- Positively charged residues mediate initial electrostatic interaction with negatively charged vesicles.
- Penetratin localizes near the water-lipid interface in a tilted orientation, with increased alpha-helical structure upon lipid binding.
- Specific charged variants (R53A/K57A, R52A/K55A) exhibited deeper membrane insertion and altered vesicle interactions.
- Tryptophan substitutions (W48F, W56F) had minimal impact on membrane insertion and destabilization.
- Cellular uptake of most variants was similar to wild-type penetratin.
- Trp48 was identified as critical for endocytosis-independent internalization.
Conclusions:
- Penetratin's charged residues are vital for initial membrane binding, while specific tryptophan residues influence internalization pathways.
- Modified penetratin variants can be designed for targeted cellular delivery with retained efficacy and safety.
- This research provides insights into peptide-based drug delivery systems and their interaction with cell membranes.