Department of Biochemistry, Institute for Research in Immunology and Cancer, Université de Montreal, Montreal, QC, Canada.
Department of Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX, USA.
Nat Commun. 2017 Dec 18;8(1):2169. doi: 10.1038/s41467-017-02257-x.
Functional selectivity of G-protein-coupled receptors is believed to originate from ligand-specific conformations that activate only subsets of signaling effectors. In this study, to identify molecular motifs playing important roles in transducing ligand binding into distinct signaling responses, we combined in silico evolutionary lineage analysis and structure-guided site-directed mutagenesis with large-scale functional signaling characterization and non-negative matrix factorization clustering of signaling profiles. Clustering based on the signaling profiles of 28 variants of the β-adrenergic receptor reveals three clearly distinct phenotypical clusters, showing selective impairments of either the Gi or βarrestin/endocytosis pathways with no effect on Gs activation. Robustness of the results is confirmed using simulation-based error propagation. The structural changes resulting from functionally biasing mutations centered around the DRY, NPxxY, and PIF motifs, selectively linking these micro-switches to unique signaling profiles. Our data identify different receptor regions that are important for the stabilization of distinct conformations underlying functional selectivity.
配体特异性构象被认为是 G 蛋白偶联受体功能选择性的起源，这种构象仅激活信号效应器的子集。在这项研究中，为了鉴定在将配体结合转化为不同信号转导反应中起重要作用的分子模体，我们结合了基于计算进化谱系分析和结构指导的定点突变，以及对信号转导谱进行大规模功能信号特征分析和非负矩阵因子聚类。基于β肾上腺素能受体 28 种变体的信号转导谱聚类，揭示了三个明显不同的表型簇，表现为 Gi 或β抑制蛋白/内吞作用途径的选择性损伤，而对 Gs 激活没有影响。使用基于模拟的误差传播来确认结果的稳健性。功能偏置突变导致的结构变化集中在 DRY、NPxxY 和 PIF 基序周围，这些微开关选择性地与独特的信号转导谱相关联。我们的数据确定了不同的受体区域，这些区域对于稳定不同构象以实现功能选择性非常重要。
