Cheng Kwan Hon, Qiu Liming, Cheng Sara Y, Vaughn Mark W
Department of Physics, Texas Tech University, Lubbock, TX 79409, USA; Department of Physics and Astronomy, Trinity University, San Antonio, TX 78212, USA.
Department of Physics, Texas Tech University, Lubbock, TX 79409, USA.
Biophys Chem. 2015 Nov;206:22-39. doi: 10.1016/j.bpc.2015.06.011. Epub 2015 Jul 4.
We have used coarse-grained (CG) and united atom (UA) molecular dynamics simulations to explore the mechanisms of protein orientational transition of a model peptide (Aβ42) in a phosphatidylcholine/cholesterol (PC/CHO) lipid bilayer. We started with an inserted state of Aβ42 containing a folded (I) or unfolded (II) K28-A42 lipid insertion domain (LID), which was stabilized by the K28-snorkeling and A42-anchoring to the PC polar groups in the lipid bilayer. After a UA-to-CG transformation and a 1000ns-CG simulation for enhancing the sampling of protein orientations, we discovered two transitions: I-to-"deep inserted" state with disrupted K28-snorkeling and II-to-"deep surface" state with disrupted A42-anchoring. The new states remained stable after a CG-to-UA transformation and a 200ns-UA simulation relaxation. Significant changes in the cholesterol-binding domain of Aβ42 and protein-induced membrane disruptions were evident after the transitions. We propose that the conformation of the LID regulates protein orientational transitions in the lipid membrane.
我们使用粗粒度(CG)和联合原子(UA)分子动力学模拟,来探究一种模型肽(Aβ42)在磷脂酰胆碱/胆固醇(PC/CHO)脂质双层中蛋白质取向转变的机制。我们从Aβ42的插入状态开始,其包含折叠的(I)或未折叠的(II)K28 - A42脂质插入结构域(LID),该结构域通过K28潜入和A42锚定到脂质双层中的PC极性基团而得以稳定。在进行UA到CG的转换以及1000ns的CG模拟以增强蛋白质取向的采样后,我们发现了两种转变:I到“深度插入”状态,其中K28潜入被破坏;II到“深度表面”状态,其中A42锚定被破坏。在CG到UA的转换以及200ns的UA模拟弛豫后,新状态保持稳定。转变后,Aβ42的胆固醇结合结构域发生了显著变化,并且蛋白质诱导的膜破坏也很明显。我们提出,LID的构象调节脂质膜中蛋白质的取向转变。