Insights into adenosine A2A receptor activation through cooperative modulation of agonist and allosteric lipid interactions
Insights into adenosine A2A receptor activation through cooperative modulation of agonist and allosteric lipid interactions
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DOI：
10.1371/journal.pcbi.1007818
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发表时间：
2020-04-01
影响因子：
4.3
通讯作者：
Giraldo, Jesus
中科院分区：
文献类型：
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作者：
Bruzzese, Agustin;Dalton, James A. R.;Giraldo, Jesus
作者摘要腺苷A2 a受体（A2 aR）的无偏微秒长度MD模拟在四倍体中进行，从apo或结合激动剂（腺苷或NECA）的非活性构象开始，它们中的每一个都嵌入两个不同的均质磷脂膜中。不同的中间体或活性受体构象被发现取决于结合激动剂的存在/不存在和脂质环境的类型。排他性地，在结合激动剂的DOPG中，我们可重复地鉴定具有完全活性特征的受体构象，其能够对接G（s）蛋白。这些不同的受体构象可归因于激动剂和磷脂介导的对受体胞内侧的变构效应的作用/不存在。动态结构数据是理解激动剂介导的GPCR激活的关键，G蛋白偶联受体（GPCRs）的激活过程已经在实验和计算上得到了广泛的研究。特别是，分子动力学（MD）模拟已被证明是有用的探索GPCR构象空间。A类GPCR的典型行为，当从它们的结晶非活性状态进行无偏MD模拟时，是在非活性和中间体构象之间波动，甚至与结合的激动剂。完全活性构象很少稳定，除非G蛋白也被结合。尽管腺苷A2 a受体（A2 aR）的几种晶体结构已经在与共结晶激动剂和G（s）蛋白的复合物中解析，但其激动剂介导的激活过程仍然没有完全理解。为了彻底研究A2 aR激活的构象景观，我们进行了无偏微秒长度的MD模拟，从非活性构象开始，无论是在载脂蛋白或结合激动剂：内源性腺苷或合成NECA，嵌入在两个均匀的磷脂膜：1，2-二油酰基-sn-甘油-3-磷酸甘油（DOPG）或1，2-二油酰基-sn-甘油-3-磷酸胆碱（DOPC）。在DOPC结合腺苷或NECA，我们观察到过渡到一个中间受体构象与已知的腺苷结合晶体状态一致。在脱辅基状态下，得到两种不同的中间构象。一个类似于在DOPC中结合腺苷所观察到的，而另一个更接近活性状态但尚未完全活性。唯一的，在DOPG与结合腺苷或NECA，我们可重复地确定受体构象与完全活性的功能，这是能够对接G（S）蛋白。这些不同的受体构象可归因于激动剂和磷脂介导的对受体胞内侧的变构效应的作用/不存在。
Author summaryUnbiased microsecond-length MD simulations of the adenosine A2a receptor (A2aR) were performed in quadruplicate, starting from the inactive conformation either in apo or with bound agonists: adenosine or NECA, each of them embedded in two different homogeneous phospholipid membranes. Different intermediate or active receptor conformations were found depending on the presence/absence of bound agonist and type of lipid environment. Exclusively, in DOPG with bound agonist, we reproducibly identify receptor conformations with fully active features, which are able to dock G(s) protein. These different receptor conformations can be attributed to the action/absence of agonist and phospholipid-mediated allosteric effects on the intracellular side of the receptor. Dynamic structural data are key for the understanding of agonist-mediated GPCR activation simulated in realistic membrane environments.The activation process of G protein-coupled receptors (GPCRs) has been extensively studied, both experimentally and computationally. In particular, Molecular Dynamics (MD) simulations have proven useful in exploring GPCR conformational space. The typical behaviour of class A GPCRs, when subjected to unbiased MD simulations from their crystallized inactive state, is to fluctuate between inactive and intermediate(s) conformations, even with bound agonist. Fully active conformation(s) are rarely stabilized unless a G protein is also bound. Despite several crystal structures of the adenosine A2a receptor (A2aR) having been resolved in complex with co-crystallized agonists and G(s) protein, its agonist-mediated activation process is still not completely understood. In order to thoroughly examine the conformational landscape of A2aR activation, we performed unbiased microsecond-length MD simulations in quadruplicate, starting from the inactive conformation either in apo or with bound agonists: endogenous adenosine or synthetic NECA, embedded in two homogeneous phospholipid membranes: 1,2-dioleoyl-sn-glycerol-3-phosphoglycerol (DOPG) or 1,2-dioleoyl-sn-glycerol-3-phosphocholine (DOPC). In DOPC with bound adenosine or NECA, we observe transition to an intermediate receptor conformation consistent with the known adenosine-bound crystal state. In apo state in DOPG, two different intermediate conformations are obtained. One is similar to that observed with bound adenosine in DOPC, while the other is closer to the active state but not yet fully active. Exclusively, in DOPG with bound adenosine or NECA, we reproducibly identify receptor conformations with fully active features, which are able to dock G(s) protein. These different receptor conformations can be attributed to the action/absence of agonist and phospholipid-mediated allosteric effects on the intracellular side of the receptor.