Hydrophobicity drives the cellular uptake of short cationic peptide ligands

Anju Gupta, Deendayal Mandal, Yousef Ahmadibeni, Keykavous Parang, Geoffrey Bothun

Research output: Contribution to journalArticlepeer-review

Abstract

Short cationic linear peptide analogs (LPAs, prepared as Arg-C n -Arg-C n -Lys, where C n represents an alkyl linkage with n = 4, 7 or 11) were synthesized and tested in human breast carcinoma BT-20 and CCRF-CEM leukemia cells for their application as targeting ligands. With constant LPA charge (+4), increasing the alkyl linkage increases the hydrophobic/hydrophilic balance and provides a systematic means of examining combined electrostatic and hydrophobic peptide-membrane interactions. Fluorescently conjugated LPA-C11 (F-LPA-C11) demonstrated significant uptake, whereas there was negligible uptake of the shorter LPAs. By varying temperature (4°C and 37°C) and cell type, the results suggest that LPA-C11 internalization is nonendocytic and nonspecific. The effect of LPA binding on the phase behavior, structure, and permeability of model membranes composed of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylserine (DPPC/DPPS, 85/15) was studied using differential scanning calorimetry (DSC), cryogenic transmission electron microscopy (cryo-TEM), and fluorescence leakage studies to gain insight into the LPA uptake mechanism. While all LPAs led to phase separation, LPA-C11, possessing the longest alkyl linkage, was able to penetrate into the bilayer and caused holes to form, which led to membrane disintegration. This was confirmed by rapid and complete dye release by LPA-C11. We propose that LPA-C11 achieves uptake by anchoring to the membrane via hydrophobicity and forming transient membrane voids. LPAs may be advantageous as drug transporter ligands because they are small, water soluble, and easy to prepare.

Original languageEnglish (US)
Pages (from-to)727-736
Number of pages10
JournalEuropean Biophysics Journal
Volume40
Issue number6
DOIs
StatePublished - Jun 2011
Externally publishedYes

Keywords

  • Calorimetry
  • Cell-penetrating peptide
  • Lipid membrane
  • Phase separation
  • Pore formation

ASJC Scopus subject areas

  • Biophysics

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