Mucha Piotr, Sikorska Emilia, Rekowski Piotr, Ruczyński Jarosław
Laboratory of Chemistry of Biologically Active Compounds, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdansk, Poland.
Environmental Nucleic Acid Laboratory, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdansk, Poland.
Cells. 2022 May 13;11(10):1638. doi: 10.3390/cells11101638.
Arginine-rich cell-penetrating peptides (RRCPPs) exhibit intrinsic neuroprotective effects on neurons injured by acute ischemic stroke. Conformational properties, interaction, and the ability to penetrate the neural membrane are critical for the neuroprotective effects of RRCCPs. In this study, we applied circular dichroism (CD) spectroscopy and coarse-grained molecular dynamics (CG MD) simulations to investigate the interactions of two RRCPPs, Tat(49-57)-NH (arginine-rich motif of Tat HIV-1 protein) and PTD4 (a less basic Ala-scan analog of the Tat peptide), with an artificial neuronal membrane (ANM). CD spectra showed that in an aqueous environment, such as phosphate-buffered saline, the peptides mostly adopted a random coil (PTD4) or a polyproline type II helical (Tat(49-57)-NH) conformation. On the other hand, in the hydrophobic environment of the ANM liposomes, the peptides showed moderate conformational changes, especially around 200 nm, as indicated by CD curves. The changes induced by the liposomes were slightly more significant in the PTD4 peptide. However, the nature of the conformational changes could not be clearly defined. CG MD simulations showed that the peptides are quickly attracted to the neuronal lipid bilayer and bind preferentially to monosialotetrahexosylganglioside (DPG1) molecules. However, the peptides did not penetrate the membrane even at increasing concentrations. This suggests that the energy barrier required to break the strong peptide-lipid electrostatic interactions was not exceeded in the simulated models. The obtained results show a correlation between the potential of mean force parameter and a peptide's cell membrane-penetrating ability and neuroprotective properties.
富含精氨酸的细胞穿透肽（RRCPPs）对急性缺血性中风损伤的神经元具有内在的神经保护作用。构象特性、相互作用以及穿透神经膜的能力对RRCCPs的神经保护作用至关重要。在本研究中，我们应用圆二色性（CD）光谱和粗粒度分子动力学（CG MD）模拟来研究两种RRCPPs，即Tat(49 - 57)-NH（Tat HIV-1蛋白的富含精氨酸基序）和PTD4（Tat肽的碱性较弱的丙氨酸扫描类似物）与人工神经元膜（ANM）的相互作用。CD光谱表明，在诸如磷酸盐缓冲盐水的水性环境中，这些肽大多呈现无规卷曲（PTD4）或多聚脯氨酸II型螺旋（Tat(49 - 57)-NH）构象。另一方面，在ANM脂质体的疏水环境中，如CD曲线所示，这些肽显示出适度的构象变化，特别是在200 nm左右。脂质体诱导的变化在PTD4肽中略显更显著。然而，构象变化的性质尚不能明确界定。CG MD模拟表明，这些肽迅速被吸引到神经元脂质双层，并优先与单唾液酸四己糖神经节苷脂（DPG1）分子结合。然而，即使在浓度增加时，这些肽也没有穿透膜。这表明在模拟模型中，打破强肽 - 脂质静电相互作用所需的能量障碍未被突破。所得结果表明平均力参数的势能与肽的细胞膜穿透能力和神经保护特性之间存在相关性。
