A Lipid Pathway for Ligand Binding Is Necessary for a Cannabinoid G Protein-coupled Receptor
A Lipid Pathway for Ligand Binding Is Necessary for a Cannabinoid G Protein-coupled Receptor
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DOI：
10.1074/jbc.m109.041590
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发表时间：
2010-06-04
影响因子：
4.8
通讯作者：
Reggio, Patricia H.
中科院分区：
文献类型：
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作者：
Hurst, Dow P.;Grossfield, Alan;Reggio, Patricia H.
最近的异硫氰酸酯共价标记研究表明，经典的大麻素(-)-7‘-isothiocyanato-11-hydroxy-1’，1‘dimethylheptyl-hexahydrocannabinol(AM841)通过脂双层(Pei，Y.，Mercier，R.W.，Anday，J.K.，Thakur，G.A.，Zvonok，A.M.，Hurst，D.，Reggio，P.H.，Janero，D.R.和Makriyannis，A.(2008)Chem)进入大麻素CB2受体。比奥尔。15、1207-1219)。然而，这种脂质途径进入的步骤序列还没有被阐明。在这里，我们检验了内源性大麻素sn-2-花生四烯基甘油(2-AG)通过脂双层与CB2受体结合的假设。为此，我们用微秒时间尺度的全原子分子动力学(MD)模拟了2-AG与CB2通过棕榈酰油酰磷脂酰胆碱脂双层的相互作用。结果表明：1)2-AG首先在跨膜α-螺旋(TMH)6/7界面从整体脂质中分离出来；2)2-AG然后通过TMH6和TMH7之间进入CB2受体结合口袋；3)2-AG头基进入CB2结合口袋足以触发细胞内TMH3/6离子锁的断裂和TMH6细胞内末端离开TMH3；4)在D3.49/D6.30质子化之后，进一步的2-AG进入配基结合口袋导致W6.48开关改变和大量水内流。据我们所知，这是第一次通过无偏分子动力学证明配体可以通过脂双层进入A类G蛋白偶联受体的结合口袋，也是第一次通过配体结合事件触发G蛋白偶联受体激活的分子动力学证明。
Recent isothiocyanate covalent labeling studies have suggested that a classical cannabinoid, (-)-7'-isothiocyanato-11-hydroxy-1',1'dimethylheptyl-hexahydrocannabinol (AM841), enters the cannabinoid CB2 receptor via the lipid bilayer (Pei, Y., Mercier, R. W., Anday, J. K., Thakur, G. A., Zvonok, A. M., Hurst, D., Reggio, P. H., Janero, D. R., and Makriyannis, A. (2008) Chem. Biol. 15, 1207-1219). However, the sequence of steps involved in such a lipid pathway entry has not yet been elucidated. Here, we test the hypothesis that the endogenous cannabinoid sn-2-arachidonoylglycerol (2-AG) attains access to the CB2 receptor via the lipid bilayer. To this end, we have employed microsecond time scale all-atom molecular dynamics (MD) simulations of the interaction of 2-AG with CB2 via a palmitoyl-oleoyl-phosphatidylcholine lipid bilayer. Results suggest the following: 1) 2-AG first partitions out of bulk lipid at the transmembrane alpha-helix (TMH) 6/7 interface; 2) 2-AG then enters the CB2 receptor binding pocket by passing between TMH6 and TMH7; 3) the entrance of the 2-AG headgroup into the CB2 binding pocket is sufficient to trigger breaking of the intracellular TMH3/6 ionic lock and the movement of the TMH6 intracellular end away from TMH3; and 4) subsequent to protonation at D3.49/D6.30, further 2-AG entry into the ligand binding pocket results in both a W6.48 toggle switch change and a large influx of water. To our knowledge, this is the first demonstration via unbiased molecular dynamics that a ligand can access the binding pocket of a class A G protein-coupled receptor via the lipid bilayer and the first demonstration via molecular dynamics of G protein-coupled receptor activation triggered by a ligand binding event.