Formation of lysozyme oligomers at model cell membranes monitored with sum frequency generation spectroscopy.
Formation of lysozyme oligomers at model cell membranes monitored with sum frequency generation spectroscopy.
复制标题
用和频发生光谱法监测模型细胞膜上溶菌酶寡聚体的形成。
DOI：
10.1021/la5010227
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
T. Weidner
中科院分区：
文献类型：
--
作者：
I. Rzeznicka;R. Pandey;M. Schleeger;M. Bonn;T. Weidner
越来越多的研究表明，有毒的低聚物，淀粉样蛋白纤维的前体，是在细胞膜，而不是在细胞的胞质区室开始形成。膜诱导的蛋白质寡聚化的研究是具有挑战性的，由于探测少量的蛋白质存在于膜表面的困难。在这里，我们采用表面敏感振动和频发生（VSFG）来研究脂质单层表面溶菌酶的二级结构。我们研究了溶菌酶在不同pH条件下在带负电荷的1，2-二棕榈酰-sn-甘油-3-（磷酸-rac-1-甘油）（DPPG）脂质单层上的聚集。脂质、蛋白质和水的分子振动随pH和表面压力的变化使我们能够同时监测溶菌酶的构象状态、脂质的组织和脂质结合水的状态的细节。在pH = 6时，溶菌酶诱导脂质层的显著无序，并且它以两种状态存在：主要具有α-螺旋含量的单体状态和寡聚体（za-mer）状态。在pH ≤ 3时，所有的膜结合溶菌酶自缔合成以反平行β折叠结构为特征的寡聚体。这与本体溶液中的情况不同，其中圆二色性（CD）显示蛋白质在中性和酸性pH条件下均保持α-螺旋构象。从单体到低聚物的转变也与脂质单层的水合作用降低有关，导致脂质酰基链有序化增加。结果表明，寡聚化需要溶菌酶纳入到脂质膜和周围吸附的溶菌酶之间的协同作用，并与膜脱水和脂质重组。发现具有反平行β-折叠结构的膜结合寡聚物使脂质膜不稳定。
A growing number of studies suggest that the formation of toxic oligomers, precursors of amyloid fibrils, is initiated at the cell membrane and not in the cytosolic compartments of the cell. Studies of membrane-induced protein oligomerization are challenging due to the difficulties of probing small numbers of proteins present at membrane surfaces. Here, we employ surface-sensitive vibrational sum frequency generation (VSFG) to investigate the secondary structure of lysozyme at the surface of lipid monolayers. We investigate lysozyme aggregation at negatively charged 1,2-dipalmitoyl-sn-glycero-3-(phospho-rac-1-glycerol) (DPPG) lipid monolayers under different pH conditions. The changes in the molecular vibrations of lipids, proteins, and water as a function of pH and surface pressure allow us to simultaneously monitor details of the conformation state of lysozyme, the organization of lipids, and the state of lipid-bound water. At pH = 6 lysozyme induces significant disordering of the lipid layer, and it exists in two states: a monomeric state with a predominantly α-helix content and an oligomeric (za-mer) state. At pH ≤ 3, all membrane-bound lysozyme self-associates into oligomers characterized by an antiparallel β-sheet structure. This is different from the situation in bulk solution, for which circular dichroism (CD) shows that the protein maintains an α-helix conformation, under both neutral and acidic pH conditions. The transition from monomers to oligomers is also associated with a decreased hydration of the lipid monolayer resulting in an increase of the lipid acyl chains ordering. The results indicate that oligomerization requires cooperative action between lysozyme incorporated into the lipid membrane and peripherally adsorbed lysozyme and is associated with the membrane dehydration and lipid reorganization. Membrane-bound oligomers with antiparallel β-sheet structure are found to destabilize lipid membranes.
影响因子：
2.9
作者：
COMPTON, LA;JOHNSON, WC
通讯作者：
JOHNSON, WC
DOI：
10.1039/c3cp50880c
发表时间：
2013-08-14
期刊：
Physical chemistry chemical physics : PCCP
影响因子：
--
作者：
Weidner T;Castner DG
通讯作者：
Castner DG
影响因子：
2.9
作者：
Sreerama, N;Woody, RW
通讯作者：
Woody, RW