TY - JOUR
T1 - Conformational states of the cell-penetrating peptide penetratin when interacting with phospholipid vesicles
T2 - Effects of surface charge and peptide concentration
AU - Magzoub, Mazin
AU - Eriksson, L. E.Göran
AU - Gräslund, Astrid
N1 - Funding Information:
We would like to thank Mr. Torbjörn Astlind for expert instrumental assistance and Dr. Jüri Jarvet for valuable help with the CD spectral analysis. This study was supported by grants from the Swedish Natural Science Research Council and from the EU program contract No. MAS3-CT97-0156.
PY - 2002/6/13
Y1 - 2002/6/13
N2 - The most commonly studied of the cell-penetrating peptides (CPP) is "penetratin" (pAntp), which functions as a carrier (vector), even for large hydrophilic (cargo) molecules. pAntp originates from the third helix of the Antennapedia homeodomain protein. The peptide is known to interact with negatively charged phospholipid vesicles, which leads to induction of secondary structure. In the present study, circular dichroism (CD) spectroscopy has been used to characterize the different secondary structures induced upon interaction with small unilamellar vesicles (SUVs) from mixtures of zwitterionic 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and negatively charged 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG). The interaction was monitored using an electron paramagnetic resonance (EPR) spin probe attached to the peptide, and the intrinsic fluorophore (tryptophan). We measured the secondary structure as a function of surface charge density, total lipid-to-peptide (L/P) molar ratio, and salt concentration, for completely bound peptide. With vesicles from POPG/POPC in a molar ratio below 30:70, at a high L/P, the peptide adopts a mainly helical conformation. Increasing the charge density, at the same L/P, promotes a higher degree of β-structure. At a fixed charge density, reducing the L/P also results in an α→β structure conversion. Hence, low membrane surface charge density and low pAntp concentration both favor a mainly helical conformation, while high charge density and pAntp concentration promote a dominating β-structure. We conclude that pAntp, when residing at the surface of a membrane, is chameleon-like in terms of its induced structure.
AB - The most commonly studied of the cell-penetrating peptides (CPP) is "penetratin" (pAntp), which functions as a carrier (vector), even for large hydrophilic (cargo) molecules. pAntp originates from the third helix of the Antennapedia homeodomain protein. The peptide is known to interact with negatively charged phospholipid vesicles, which leads to induction of secondary structure. In the present study, circular dichroism (CD) spectroscopy has been used to characterize the different secondary structures induced upon interaction with small unilamellar vesicles (SUVs) from mixtures of zwitterionic 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and negatively charged 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG). The interaction was monitored using an electron paramagnetic resonance (EPR) spin probe attached to the peptide, and the intrinsic fluorophore (tryptophan). We measured the secondary structure as a function of surface charge density, total lipid-to-peptide (L/P) molar ratio, and salt concentration, for completely bound peptide. With vesicles from POPG/POPC in a molar ratio below 30:70, at a high L/P, the peptide adopts a mainly helical conformation. Increasing the charge density, at the same L/P, promotes a higher degree of β-structure. At a fixed charge density, reducing the L/P also results in an α→β structure conversion. Hence, low membrane surface charge density and low pAntp concentration both favor a mainly helical conformation, while high charge density and pAntp concentration promote a dominating β-structure. We conclude that pAntp, when residing at the surface of a membrane, is chameleon-like in terms of its induced structure.
KW - Interaction
KW - Penetratin
KW - Phospholipid vesicle
KW - Secondary structure
KW - Surface charge
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U2 - 10.1016/S0005-2736(02)00373-5
DO - 10.1016/S0005-2736(02)00373-5
M3 - Article
C2 - 12007625
AN - SCOPUS:0037071786
SN - 0005-2736
VL - 1563
SP - 53
EP - 63
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
IS - 1-2
ER -