Jurczak Przemyslaw, Sikorska Emilia, Czaplewska Paulina, Rodziewicz-Motowidlo Sylwia, Zhukov Igor, Szymanska Aneta
Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
Intercollegiate Faculty of Biotechnology UG & MUG, University of Gdańsk, Gdańsk, Abrahama 58, 80-307 Gdańsk, Poland.
Membranes (Basel). 2020 Dec 24;11(1):17. doi: 10.3390/membranes11010017.
Human cystatin C (CC), a member of the superfamily of papain-like cysteine protease inhibitors, is the most widespread cystatin in human body fluids. Physiologically active CC is a monomer, which dimerization and oligomerization lead to the formation of the inactive, insoluble amyloid form of the protein, strictly associated with cerebral amyloid angiopathy, a severe state causing death among young patients. It is known, that biological membranes may accelerate the oligomerization processes of amyloidogenic proteins. Therefore, in this study, we describe an influence of membrane mimetic environment-mixed dodecylphosphocholine:sodium dodecyl sulfate (DPC:SDS) micelle (molar ratio 5:1)-on the effect of the CC oligomerization. The CC-micelle interactions were analyzed with size exclusion chromatography, circular dichroism, and nuclear magnetic resonance spectroscopy. The experiments were performed on the wild-type (WT) cystatin C, and two CC variants-V57P and V57G. Collected experimental data were supplemented with molecular dynamic simulations, making it possible to highlight the binding interface and select the residues involved in interactions with the micelle. Obtained data shows that the mixed DPC:SDS micelle does not accelerate the oligomerization of protein and even reverses the CC dimerization process.
人胱抑素C（CC）是木瓜蛋白酶样半胱氨酸蛋白酶抑制剂超家族的成员，是人体体液中分布最广泛的胱抑素。具有生理活性的CC是一种单体，其二聚化和寡聚化会导致形成无活性、不溶性的淀粉样蛋白形式，这与脑淀粉样血管病密切相关，脑淀粉样血管病是一种导致年轻患者死亡的严重疾病。众所周知，生物膜可能会加速淀粉样蛋白的寡聚化过程。因此，在本研究中，我们描述了膜模拟环境——混合十二烷基磷酰胆碱：十二烷基硫酸钠（DPC:SDS）胶束（摩尔比5:1）——对CC寡聚化作用的影响。通过尺寸排阻色谱、圆二色光谱和核磁共振光谱分析了CC与胶束的相互作用。实验针对野生型（WT）胱抑素C以及两种CC变体——V57P和V57G进行。收集的实验数据辅以分子动力学模拟，从而能够突出结合界面并选择参与与胶束相互作用的残基。获得的数据表明，混合的DPC:SDS胶束不会加速蛋白质的寡聚化，甚至会逆转CC的二聚化过程。
