Activation of PKA via asymmetric allosteric coupling of structurally conserved cyclic nucleotide binding domains
Activation of PKA via asymmetric allosteric coupling of structurally conserved cyclic nucleotide binding domains
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DOI：
10.1038/s41467-019-11930-2
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发表时间：
2019-09-04
影响因子：
16.6
通讯作者：
Maillard, Rodrigo A.
中科院分区：
文献类型：
--
作者：
Hao, Yuxin;England, Jeneffer P.;Maillard, Rodrigo A.
环核苷酸结合（CNB）结构域变构调节多种功能蛋白的活性，但使环核苷酸结合信号调节远端结构域的机制尚不清楚。在这里，我们使用光学镊子和分子动力学来剖析与camp结合信号在蛋白激酶A （PKA）的两个CNB结构域之间转导相关的折叠能量格局的变化。我们发现，cAMP结合对能量格局的响应是特定于结构域的，导致了独特但相互协调的任务：一个CNB结构域启动cAMP结合和合作，而另一个则触发结构域间的相互作用，促进活性构象。结构域间的相互作用以循序渐进的方式发生，从载脂蛋白和camp结合结构域之间的中间配体状态开始。此外，我们确定了一个cAMP响应开关，N3A基序，其构象和稳定性取决于cAMP占用。该开关作为信号中枢，在PKA激活过程中放大camp结合信号。
Cyclic nucleotide-binding (CNB) domains allosterically regulate the activity of proteins with diverse functions, but the mechanisms that enable the cyclic nucleotide-binding signal to regulate distant domains are not well understood. Here we use optical tweezers and molecular dynamics to dissect changes in folding energy landscape associated with cAMP-binding signals transduced between the two CNB domains of protein kinase A (PKA). We find that the response of the energy landscape upon cAMP binding is domain specific, resulting in unique but mutually coordinated tasks: one CNB domain initiates cAMP binding and cooperativity, whereas the other triggers inter-domain interactions that promote the active conformation. Inter-domain interactions occur in a stepwise manner, beginning in intermediate-liganded states between apo and cAMP-bound domains. Moreover, we identify a cAMP-responsive switch, the N3A motif, whose conformation and stability depend on cAMP occupancy. This switch serves as a signaling hub, amplifying cAMP-binding signals during PKA activation.