Nejvíce citovaný článek - PubMed ID 32603116
Effect of Helical Kink on Peptide Translocation across Phospholipid Membranes
Despite ongoing research on antimicrobial peptides (AMPs) and cell-penetrating peptides (CPPs), their precise translocation mechanism remains elusive. This includes Buforin 2 (BF2), a well-known AMP, for which spontaneous translocation across the membrane has been proposed but a high barrier has been calculated. Here, we used computer simulations to investigate the effect of a nonequilibrium situation where the peptides are adsorbed on one side of the lipid bilayer, mimicking experimental conditions. We demonstrated that the asymmetric membrane adsorption of BF2 enhances its translocation across the lipid bilayer by lowering the energy barrier by tens of kJ mol-1. We showed that asymmetric membrane adsorption also reduced the free energy barrier of lipid flip-flop but remained unlikely even at BF2 surface saturation. These results provide insight into the driving forces behind membrane translocation of cell-penetrating peptides in nonequilibrium conditions, mimicking experiments.
- MeSH
- adsorpce MeSH
- antimikrobiální peptidy chemie farmakologie MeSH
- buněčná membrána metabolismus chemie MeSH
- kationické antimikrobiální peptidy chemie farmakologie metabolismus MeSH
- lipidové dvojvrstvy * chemie metabolismus MeSH
- penetrační peptidy chemie metabolismus MeSH
- proteiny MeSH
- simulace molekulární dynamiky MeSH
- termodynamika MeSH
- terpeny chemie farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antimikrobiální peptidy MeSH
- buforin II MeSH Prohlížeč
- kationické antimikrobiální peptidy MeSH
- lipidové dvojvrstvy * MeSH
- penetrační peptidy MeSH
- proteiny MeSH
- terpeny MeSH
Cell membranes act as semi-permeable barriers, often restricting the entry of large or hydrophilic molecules. Nonetheless, certain amphiphilic molecules, such as antimicrobial and cell-penetrating peptides, can cross these barriers. In this study, we demonstrate that specific properties of transmembrane proteins/peptides can enhance membrane permeation of amphiphilic peptides. Using coarse-grained molecular dynamics with free-energy calculations, we identify key translocation-enhancing attributes of transmembrane proteins/peptides: a continuous hydrophilic patch, charged residues preferably in the membrane center, and aromatic hydrophobic residues. By employing both coarse-grained and atomistic simulations, complemented by experimental validation, we show that these properties not only enhance peptide translocation but also speed up lipid flip-flop. The enhanced flip-flop reinforces the idea that proteins such as scramblases and insertases not only share structural features but also operate through identical biophysical mechanisms enhancing the insertion and translocation of amphiphilic molecules. Our insights offer guidelines for the designing of translocation-enhancing proteins/peptides that could be used in medical and biotechnological applications.
- MeSH
- buněčná membrána metabolismus chemie MeSH
- hydrofobní a hydrofilní interakce * MeSH
- lipidové dvojvrstvy chemie metabolismus MeSH
- membránové proteiny * chemie metabolismus MeSH
- simulace molekulární dynamiky * MeSH
- transport proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- lipidové dvojvrstvy MeSH
- membránové proteiny * MeSH
The transport of molecules across cell membranes is vital for proper cell function and effective drug delivery. While most cell membranes naturally possess an asymmetric lipid composition, research on membrane transport predominantly uses symmetric lipid membranes. The permeation through the asymmetric membrane is then calculated as a sum of the inverse permeabilities of leaflets from symmetric bilayers. In this study, we examined how two types of amphiphilic molecules translocate across both asymmetric and symmetric membranes. Using computer simulations with both coarse-grained and atomistic force fields, we calculated the free energy profiles for the passage of model amphiphilic peptides and a lipid across various membranes. Our results consistently demonstrate that while the free energy profiles for asymmetric membranes with a small differential stress concur with symmetric ones in the region of lipid headgroups, the profiles differ around the center of the membrane. In this region, the free energy for the asymmetric membrane transitions between the profiles for two symmetric membranes. In addition, we show that peptide permeability through an asymmetric membrane cannot always be predicted from the permeabilities of the symmetric membranes. This indicates that using symmetric membranes falls short in providing an accurate depiction of peptide translocation across asymmetric membranes.
Cell membranes are phospholipid bilayers with a large number of embedded transmembrane proteins. Some of these proteins, such as scramblases, have properties that facilitate lipid flip-flop from one membrane leaflet to another. Scramblases and similar transmembrane proteins could also affect the translocation of other amphiphilic molecules, including cell-penetrating or antimicrobial peptides. We studied the effect of transmembrane proteins on the translocation of amphiphilic peptides through the membrane. Using two very different models, we consistently demonstrate that transmembrane proteins with a hydrophilic patch enhance the translocation of amphiphilic peptides by stabilizing the peptide in the membrane. Moreover, there is an optimum amphiphilicity because the peptide could become overstabilized in the transmembrane state, in which the peptide-protein dissociation is hampered, limiting the peptide translocation. The presence of scramblases and other proteins with similar properties could be exploited for more efficient transport into cells. The described principles could also be utilized in the design of a drug-delivery system by the addition of a translocation-enhancing peptide that would integrate into the membrane.
