Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany.
Nat Commun. 2017 Nov 22;8(1):1681. doi: 10.1038/s41467-017-01715-w.
AKAP79/150 is essential for coordinating second messenger-responsive enzymes in processes including synaptic long-term depression. Ca directly regulates AKAP79 through its effector calmodulin (CaM), but the molecular basis of this regulation was previously unknown. Here, we report that CaM recognizes a '1-4-7-8' pattern of hydrophobic amino acids starting at Trp79 in AKAP79. Cross-linking coupled to mass spectrometry assisted mapping of the interaction site. Removal of the CaM-binding sequence in AKAP79 prevents formation of a Ca-sensitive interface between AKAP79 and calcineurin, and increases resting cellular PKA phosphorylation. We determined a crystal structure of CaM bound to a peptide encompassing its binding site in AKAP79. CaM adopts a highly compact conformation in which its open Ca-activated C-lobe and closed N-lobe cooperate to recognize a mixed α/3 helix in AKAP79. The structure guided a bioinformatic screen to identify potential sites in other proteins that may employ similar motifs for interaction with CaM.
AKAP79/150 对于协调包括突触长时程抑制在内的各种过程中的第二信使反应性酶是必不可少的。Ca 通过其效应物钙调蛋白 (CaM) 直接调节 AKAP79，但这种调节的分子基础以前是未知的。在这里，我们报告说 CaM 识别 AKAP79 中从色氨酸 79 开始的“1-4-7-8”疏水氨基酸模式。交联与质谱联用辅助相互作用位点的作图。从 AKAP79 中去除 CaM 结合序列可防止 AKAP79 和钙调磷酸酶之间形成 Ca 敏感界面，并增加静止细胞中的 PKA 磷酸化。我们确定了 CaM 与包含其在 AKAP79 中结合位点的肽的晶体结构。CaM 采用高度紧凑的构象，其中其开放的 Ca 激活的 C 结构域和闭合的 N 结构域协同识别 AKAP79 中的混合 α/3 螺旋。该结构指导生物信息学筛选以识别其他蛋白质中可能使用类似基序与 CaM 相互作用的潜在位点。
