Sankararamakrishnan R, Sansom M S
Laboratory of Molecular Biophysics, University of Oxford, UK.
FEBS Lett. 1995 Dec 27;377(3):377-82. doi: 10.1016/0014-5793(95)01376-8.
The ion channel of the nicotinic acetylcholine receptor is a water-filled pore formed by five M2 helix segments, one from each subunit. Molecular dynamics simulations on bundles of five M2 alpha 7 helices surrounding a central column of water and with caps of water molecules at either end of the pore have been used to explore the effects of intrapore water on helix packing. Interactions of water molecules with the N-terminal polar sidechains lead to a conformational transition from right- to left-handed supercoils during these stimulations. These studies reveal that the pore formed by the bundle of M2 helices is flexible. A structural role is proposed for water molecules in determining the geometry of bundles of isolated pore-forming helices.
烟碱型乙酰胆碱受体的离子通道是一个由五个M2螺旋片段构成的充满水的孔道，每个亚基各有一个。对围绕着中央水柱且在孔道两端带有水分子帽的五个M2α7螺旋束进行分子动力学模拟，以探究孔道内水对螺旋堆积的影响。在这些模拟过程中，水分子与N端极性侧链的相互作用导致构象从右手超螺旋转变为左手超螺旋。这些研究表明，由M2螺旋束形成的孔道具有柔韧性。有人提出水分子在确定孤立的成孔螺旋束的几何形状方面具有结构作用。
