Walrant Astrid, Vogel Alexander, Correia Isabelle, Lequin Olivier, Olausson Bjoern E S, Desbat Bernard, Sagan Sandrine, Alves Isabel D
UPMC-Paris 06, UMR 7203 CNRS, ENS, Laboratoire des BioMolecules, 4, place jussieu, Paris F-75005, France.
Biochim Biophys Acta. 2012 Jul;1818(7):1755-63. doi: 10.1016/j.bbamem.2012.02.024.
Cell penetrating peptides (CPPs) can cross cell membranes in a receptor independent manner and transport cargo molecules inside cells. These peptides can internalize through two independent routes: energy dependent endocytosis and energy independent translocation across the membrane, but the exact mechanisms are still unknown. The interaction of the CPP with different membrane components is certainly a preliminary key point that triggers internalization, such as the interaction with lipids to lead to the translocation process. In this study, we used two arginine-rich peptides, RW9 (RRWWRRWRR-NH2), which is a potent CPP, and RL9 (RRLLRRLRR-NH2) that, although binding tightly and accumulating on membranes, does not enter into cells. Using a set of experimental and theoretical techniques, we studied the binding, insertion and orientation of the peptides into different model membranes as well as the subsequent membrane reorganization. Herein we show that although the two peptides had rather similar behavior regarding lipid membrane interaction, subtle differences were found concerning the depth of peptide insertion, effect on the lipid chain ordering and kinetics of peptide insertion in the membrane, which altogether might explain their different cell internalization capacities. Molecular dynamics simulation studies show that some peptide molecules flipped their orientation over the course of the simulation such that the hydrophobic residues penetrated deeper in the lipid core region while Arg-residues maintained H-bonds with the lipid headgroups, serving as a molecular hinge in a conformation that appeared to correspond to the equilibrium one.
细胞穿透肽（CPPs）能够以不依赖受体的方式穿过细胞膜，并将货物分子转运到细胞内部。这些肽可以通过两条独立的途径内化：能量依赖性内吞作用和不依赖能量的跨膜转运，但具体机制仍不清楚。CPP与不同膜成分的相互作用无疑是触发内化的一个初步关键点，例如与脂质的相互作用导致转运过程。在本研究中，我们使用了两种富含精氨酸的肽，RW9（RRWWRRWRR-NH2），它是一种有效的CPP，以及RL9（RRLLRRLRR-NH2），虽然它紧密结合并积聚在膜上，但不会进入细胞。我们使用了一系列实验和理论技术，研究了这些肽在不同模型膜中的结合、插入和取向以及随后的膜重组。在此我们表明，尽管这两种肽在脂质膜相互作用方面具有相当相似的行为，但在肽插入深度、对脂质链有序性的影响以及肽在膜中的插入动力学方面发现了细微差异，这些差异可能共同解释了它们不同的细胞内化能力。分子动力学模拟研究表明，一些肽分子在模拟过程中翻转了它们的取向，使得疏水残基在脂质核心区域中更深地穿透，而精氨酸残基与脂质头部基团保持氢键，在一种似乎对应于平衡构象的构象中充当分子铰链。
