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- Bárány-Wallje, Elsa, et al.
(författare)
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A critical reassessment of penetratin translocation across lipid membranes.
- 2005
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Ingår i: Biophys J. - 0006-3495. ; 89:4, s. 2513-21
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Tidskriftsartikel (refereegranskat)abstract
- Penetratin is a short, basic cell-penetrating peptide able to induce cellular uptake of a vast variety of large, hydrophiliccargos. We have reassessed the highly controversial issue of direct permeation of the strongly cationic peptide across negatively charged lipid membranes. Confocal laser scanning microscopy on rhodamine-labeled giant vesicles incubated with carboxyfluorescein-labeled penetratin yielded no evidence of transbilayer movement, in contradiction to previously reported results. Confocal fluorescence spectroscopy on black lipid membranes confirmed this finding, which was also not affected by application of a transmembrane electric potential difference.A novel dialysis assay based on tryptophan absorbance and fluorescence spectroscopy demonstrated that the permeability of small and large unilamellar vesicles to penetratin is,<10^-13m/s.Taken together, the results show that penetratin is not capable of overcoming model membrane systems irrespective of the bilayer curvature or the presence of a transmembrane voltage. Thus, direct translocation across the hydrophobic core of the plasmamembrane cannot account for the efficient uptake of penetratin into live cells, which is in accord with recent in vitro studies underlining the importance of endocytosis in the internalization process of cationic cell-penetrating peptides.
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| 2. |
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| 3. |
- Bárány-Wallje, Elsa, 1979-
(författare)
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Biophysical studies of cell-penetrating peptides and of the RNR inhibitor Sml1
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Several short peptides, so called cell-penetrating peptides, have the capability to transport large hydrophilic cargos through the cell membrane. The objective is to use these peptides as drug carriers and thereby enhance the uptake of drugs into cells.Three different cell-penetrating peptides are characterized in this thesis. Structure and dynamics of transportan when bound to phospholipid bicelles was determined using NMR. The hydrophobic peptide transportan and its deletion analogue Tp10 both bind to lipid head-group region of the membrane as amphipathic α-helices (papers I & II) and they were found to cause leakage in vesicles (paper IV). The membrane disturbing effect is probably part of how these peptides are translocated through the cell membrane, but also an explanation to why these peptides are found to be toxic in vivo. The high degree of toxicity limits their usefulness. We however also found that the membrane disturbing effect was significantly reduced when a large hydrophilic cargo was attached, which indicates that the properties of the whole peptide-cargo complex has to be taken into account (paper IV).The highly charged cell-penetrating peptide penetratin is not nearly as membrane disturbing as transportan (papers III and IV). Penetratin binds preferably to negatively charged membranes by electrostatic interactions. We used several different techniques to investigate if penetratin could be translocated through membrane model systems. All experiments consistently suggested that penetratin could not be translocated into model systems. It indicates an endocytotic uptake mechanism into cells rather than a direct membrane penetration (paper III). The ribonucleotide reductase inhibitor protein Sml1 was characterized using NMR and CD spectroscopy (paper V). Three different secondary structure elements were found, in agreement with previous NMR studies, but Sml1 does not have a well defined three-dimensional structure in solution. The N-terminus includes an α-helical region between residues 4-14 and we propose that this region interacts with the C-terminal part of the protein in the monomeric form. The N-terminus is also suggested to be a dimerization interface. Dimers are formed at concentrations above 10 µM in solution. The C-terminal region of Sml1 includes an α-helix between residues 61-80 that is crucial for binding and inhibition of RNR.
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| 4. |
- Bárány-Wallje, Elsa, et al.
(författare)
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Differential membrane perturbation caused by the cell penetrating peptide Tp10 depending on attached cargo
- 2007
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 581:13, s. 2389-2393
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Tidskriftsartikel (refereegranskat)abstract
- The membrane leakage caused by the cell penetrating peptide Tp10, a variant of transportan, was studied in large unilamellar vesicles with the entrapped fluorophore calcein. The vesicles were composed of zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. A significant decrease in membrane leakage was found when the 55 kDa streptavidin protein was attached to Tp10. When a 5.4 kDa peptide nucleic acid molecule was attached, the membrane leakage was comparable to that caused by Tp10 alone. The results suggest that direct membrane effects may cause membrane translocation of Tp10 alone and of smaller complexes, whereas these effects do not contribute for larger cargoes.
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| 5. |
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| 6. |
- Bárány-Wallje, Elsa, et al.
(författare)
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Dynamics of transportan in bicelles is surface charge dependent.
- 2006
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Ingår i: J Biomol NMR. - 0925-2738. ; 35:2, s. 137-47
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Tidskriftsartikel (refereegranskat)abstract
- In this study we investigated the dynamic behavior of the chimeric cell-penetrating peptide transportan in membrane-like environments using NMR. Backbone amide 15N spin relaxation was used to investigate the dynamics in two bicelles: neutral DMPC bicelles and partly negatively charged DMPG-containing bicelles.The structure of the peptide as judged from CD and chemical shifts is similar in the two cases. Both the overall motion as well as the local dynamics is, however, different in the two types of bicelles. The overall dynamics of the peptide is significantly slower in the partly negatively charged bicelle environment, as evidenced by longer global correlation times for all measured sites.The local motion, as judged from generalized order parameters, is for all sites in the peptide more restricted when bound to negatively charged bicelles than when bound to neutral bicelles (increase in S2 is on average 0.11±0.07). The slower dynamics of transportan in charged membrane model systems cause significant line broadening in the proton NMR spectrum, which in certain cases limits the observation of 1H signals for transportan when bound to the membrane. The effect of transportan on DMPC and DHPC motion in zwitterionic bicelles was also investigated, and the motion of both components in the bicelle was found to be affected.
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| 7. |
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| 8. |
- Bárány-Wallje, Elsa, et al.
(författare)
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NMR solution structure and position of transportan in neutral phospholipid bicelles.
- 2004
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Ingår i: FEBS Lett. - 0014-5793. ; 567:2-3, s. 265-9
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Tidskriftsartikel (refereegranskat)abstract
- Transportan is a chimeric cell-penetrating peptide constructed from the peptides galanin and mastoparan, which has the ability to internalize living cells carrying a hydrophilic load. In this study, we have determined the NMR solution structure and investigated the position of transportan in neutral bicelles. The structure revealed a well-defined -helix in the C-terminal mastoparan part of the peptide and a weaker tendency to form an -helix in the N-terminal domain. The position of the peptide in relation to the membrane, as studied by adding paramagnetic probes, shows that the peptide lies parallel to, and in the head-group region of the membrane surface. This result is supported by amide proton secondary chemical shifts.
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