Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark.
Protein Eng Des Sel. 2011 Jan;24(1-2):89-97. doi: 10.1093/protein/gzq095. Epub 2010 Nov 22.
Membranes not only provide cellular compartmentalization but influence protein behavior and folding by virtue of the multitude of different lipid types. We have studied the impact of lipid composition on the folding of the membrane-associated protein Mistic from B. subtilis. We use dimerisation via the single Cys3 residue as monitor for the degree of correct folding, since mis- or unfolding will expose the otherwise buried Cys3. We find great variability in how lipids affect protein production and dimerization, ranging from high production and low dimerization via increased production and higher dimerization to low production and low dimerization. Phosphocholine (PC) vesicles, in particular di-oleoyl-PC, lead to the highest production levels. Shorter chain lengths lead to reduced production but higher levels of dimerization. Different lipids may promote correct folding of Mistic to different extents, mediated by proper hydrophobic matching (attained for long-chain but not short-chain PC vesicles) and the existence of a fluid phase (the gel phase reduces production as well as dimerization, probably by immobilizing Mistic on the surface). The very fact that different lipids have an effect indicates that Mistic behaves like a bona fide membrane protein with a clear preference for membranes of a certain thickness and flexibility.
膜不仅提供了细胞区室化，还通过多种不同的脂质类型影响蛋白质的行为和折叠。我们研究了脂质组成对枯草芽孢杆菌膜相关蛋白 Mistic 折叠的影响。我们使用单个 Cys3 残基的二聚化作为正确折叠程度的监测，因为错误折叠或展开会暴露原本埋藏的 Cys3。我们发现脂质对蛋白质产生和二聚化的影响存在很大的可变性，从高产量和低二聚化到高产量和高二聚化，再到低产量和低二聚化。磷酸胆碱（PC）囊泡，特别是二油酰基-PC，导致最高的产量水平。较短的链长导致产量降低，但二聚化水平升高。不同的脂质可能以不同的程度促进 Mistic 的正确折叠，这是通过适当的疏水性匹配（长链 PC 囊泡实现，但短链 PC 囊泡不行）和存在流动相（凝胶相降低产量和二聚化，可能是通过将 Mistic 固定在表面上）介导的。不同的脂质会产生影响，这一事实表明 Mistic 表现得像一种真正的膜蛋白，对特定厚度和柔韧性的膜有明显的偏好。
