High‐density lipoproteins (HDLs) are responsible for removing cholesterol from arterial walls, through a process known as reverse cholesterol transport. The main protein in HDL, apolipoprotein A‐I (ApoA‐I), is essential to this process, and changes in its sequence significantly alter HDL structure and functions. ApoA‐I amyloidogenic variants, associated with a particular hereditary degenerative disease, are particularly effective at facilitating cholesterol removal, thus protecting carriers from cardiovascular disease. Thus, it is conceivable that reconstituted HDL (rHDL) formulations containing ApoA‐I proteins with functional/structural features similar to those of amyloidogenic variants hold potential as a promising therapeutic approach. Here we explored the effect of protein cargo and lipid composition on the function of rHDL containing one of the ApoA‐I amyloidogenic variants G26R or L174S by Fourier transformed infrared spectroscopy and neutron reflectometry. Moreover, small‐angle x‐ray scattering uncovered the structural and functional differences between rHDL particles, which could help to comprehend higher cholesterol efflux activity and apparent lower phospholipid (PL) affinity. Our findings indicate distinct trends in lipid exchange (removal vs. deposition) capacities of various rHDL particles, with the rHDL containing the ApoA‐I amyloidogenic variants showing a markedly lower ability to remove lipids from artificial membranes compared to the rHDL containing the native protein. This effect strongly depends on the level of PL unsaturation and on the particles' ultrastructure. The study highlights the importance of the protein cargo, along with lipid composition, in shaping rHDL structure, contributing to our understanding of lipid–protein interactions and their behavior.

中文翻译：

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人工膜重构高密度脂蛋白中载脂蛋白 A-I 淀粉样变体的脂质交换

高密度脂蛋白 (HDL) 负责通过称为反向胆固醇转运的过程从动脉壁去除胆固醇。 HDL 中的主要蛋白质载脂蛋白 A-I (ApoA-I) 对此过程至关重要，其序列的变化会显着改变 HDL 的结构和功能。 ApoA-I 淀粉样变体与特定的遗传性退行性疾病相关，在促进胆固醇去除方面特别有效，从而保护携带者免受心血管疾病的侵害。因此，可以想象，含有与淀粉样变体相似的功能/结构特征的 ApoA-I 蛋白的重构 HDL (rHDL) 制剂具有作为一种有前途的治疗方法的潜力。在这里，我们通过傅里叶变换红外光谱和中子反射测定法探讨了蛋白质货物和脂质成分对含有 ApoA-I 淀粉样变体 G26R 或 L174S 之一的 rHDL 功能的影响。此外，小角度 X 射线散射揭示了 rHDL 颗粒之间的结构和功能差异，这有助于理解较高的胆固醇流出活性和明显较低的磷脂 (PL) 亲和力。我们的研究结果表明，各种 rHDL 颗粒的脂质交换（去除与沉积）能力存在明显的趋势，与含有天然蛋白的 rHDL 相比，含有 ApoA-I 淀粉样变体的 rHDL 从人造膜上去除脂质的能力明显较低。这种效应很大程度上取决于 PL 不饱和度水平和颗粒的超微结构。该研究强调了蛋白质货物以及脂质成分在塑造 rHDL 结构中的重要性，有助于我们了解脂质-蛋白质相互作用及其行为。