A residue outside the binding site determines the Gα binding specificity of GoLoco motifs
A residue outside the binding site determines the Gα binding specificity of GoLoco motifs
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结合位点外的残基决定了 GoLoco 基序的 Gα 结合特异性
DOI：
10.1021/acs.biochem.8b00848
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发表时间：
2018
期刊：
影响因子：
2.9
通讯作者：
Wenning Wang
中科院分区：
文献类型：
--
作者：
Chunhua Liu;Jingwei Weng;Dan Wang;Maohua Yang;Min Jia;Wenning Wang
含有GoLoco基序的蛋白在各种信号通路中调节Gα蛋白的核苷酸结合状态。作为鸟嘌呤核苷酸解离抑制剂（GDIs），它们与Gα·GDP结合并抑制GDP与GTP的交换。GoLoco蛋白对Gα家族的不同成员表现出结合选择性。虽然Gαi1·GDP/RGS 14晶体结构很好地解释了RGS 14 GoLoco结构域的特异性结合选择性，但对于在GPSM 2/LGN/dPins和GPSM 1/AGS 3等蛋白质中串联阵列中发现的短GoLoco结构域的更一般特征，选择性结合的机制尚未被理解。探讨了GoLoco蛋白LGN与hG α i3和hG αo的差异相互作用机制。结合突变实验和分子动力学模拟，我们发现了一个远离结合界面的残基（Asp 229），它显著影响LGN和hG αi/o之间的相互作用。该位置处的带负电荷的残基是高结合亲和力所需的。hG α i2和dG αo进一步证实了这一亲和力调节机制，表明该途径在Gα家族成员中是保守的。
GoLoco motif-containing proteins regulate the nucleotide-binding state of Gα proteins in various signaling pathways. As guanine nucleotide dissociation inhibitors (GDIs), they bind Gα·GDP and inhibit GDP to GTP exchange. GoLoco proteins show binding selectivity toward different members of the Gα family. Although the Gαi1·GDP/RGS14 crystal structure explains the specific binding selectivity of the RGS14 GoLoco domain well, the mechanism of selective binding has not been understood for the more general features of short GoLoco domains found in tandem arrays in proteins like GPSM2/LGN/dPins and GPSM1/AGS3. We explored the mechanism of differential interactions of GoLoco protein LGN withhGαi3andhGαo. By combining mutagenesis experiments and molecular dynamics simulations, we identified a residue (Asp229 inhGαi3) away from the binding interface that remarkably affects the interaction between LGN andhGαi/o. A negatively charged residue at this position is required for high binding affinity. This affinity regulation mechanism was further verified by the cases ofhGαi2anddGαo, suggesting that this pathway is conserved among members of the Gα family.