A cell-penetrating peptide (CPP) is a short amino-acid sequence capable of efficiently translocating across the cellular membrane of mammalian cells. However, the potential of CPPs as a delivery vector is hampered by the strong reduction of its translocation efficiency when it bears an attached molecular cargo. To overcome this problem, we used previously developed diblock copolymers of elastin-like polypeptides (ELPs), which we end functionalized with TAT (transactivator of transcription), an archetypal CPP built from a positively charged amino acid sequence of the HIV-1 virus. These ELPs self-assemble into micelles at a specific temperature and present the TAT peptide on their corona. These micelles can recover the lost membrane affinity of TAT and can trigger interactions with the membrane despite the presence of a molecular cargo. Herein, we study the influence of membrane surface charge on the adsorption of TAT-functionalized ELP micelles onto giant unilamellar vesicles (GUVs). We show that the TAT-ELP micelles show an increased binding constant toward negatively charged membranes compared to neutral membranes, but no translocation is observed. The affinity of the TAT-ELP micelles for the GUVs displays a stepwise dependence on the lipid charge of the GUV, which, to our knowledge, has not been reported previously for interactions between peptides and lipid membranes. By unveiling the key steps controlling the interaction of an archetypal CPP with lipid membranes, through regulation of the charge of the lipid bilayer, our results pave the way for a better design of delivery vectors based on CPPs.

中文翻译：

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负脂膜增强TAT修饰的弹性蛋白样多肽胶束的吸附

细胞穿透肽（CPP）是一种短氨基酸序列，能够有效地跨过哺乳动物细胞的细胞膜。然而，当 CPP 带有附着的分子货物时，其易位效率会大幅降低，从而阻碍了 CPP 作为递送载体的潜力。为了克服这个问题，我们使用了之前开发的弹性蛋白样多肽 (ELP) 的二嵌段共聚物，并用 TAT（转录反式激活因子）对其进行功能化，TAT 是一种由 HIV-1 病毒带正电荷的氨基酸序列构建的原型 CPP。这些 ELP 在特定温度下自组装成胶束，并在其冠上呈现 TAT 肽。这些胶束可以恢复 TAT 失去的膜亲和力，并且可以触发与膜的相互作用，尽管存在分子货物。在此，我们研究了膜表面电荷对 TAT 功能化 ELP 胶束吸附到巨型单层囊泡 (GUV) 上的影响。我们发现，与中性膜相比，TAT-ELP 胶束对带负电膜的结合常数增加，但没有观察到易位。 TAT-ELP 胶束对 GUV 的亲和力显示出对 GUV 脂质电荷的逐步依赖性，据我们所知，此前尚未报道肽与脂质膜之间的相互作用。通过揭示控制原型 CPP 与脂质膜相互作用的关键步骤，通过调节脂质双层的电荷，我们的结果为更好地设计基于 CPP 的递送载体铺平了道路。