Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA.
Nat Struct Mol Biol. 2013 Mar;20(3):355-62. doi: 10.1038/nsmb.2497. Epub 2013 Feb 3.
Phospholipase C-β (PLCβ) is directly activated by Gαq, but the molecular basis for how its distal C-terminal domain (CTD) contributes to maximal activity is poorly understood. Herein we present both the crystal structure and cryo-EM three-dimensional reconstructions of human full-length PLCβ3 in complex with mouse Gαq. The distal CTD forms an extended monomeric helical bundle consisting of three antiparallel segments with structural similarity to membrane-binding bin-amphiphysin-Rvs (BAR) domains. Sequence conservation of the distal CTD suggests putative membrane and protein interaction sites, the latter of which bind the N-terminal helix of Gαq in both the crystal structure and cryo-EM reconstructions. Functional analysis suggests that the distal CTD has roles in membrane targeting and in optimizing the orientation of the catalytic core at the membrane for maximal rates of lipid hydrolysis.
磷酯酶 C-β（PLCβ）可被 Gαq 直接激活，但人们对其远端 C 端结构域（CTD）如何促进最大活性的分子基础知之甚少。在此，我们呈现了与人全长 PLCβ3 与鼠 Gαq 形成复合物的晶体结构和冷冻电镜三维重构。远端 CTD 形成了一个延伸的单体螺旋束，由三个反平行片段组成，其结构与膜结合的双 Amphiphysin-Rvs（BAR）结构域相似。远端 CTD 的序列保守性提示存在潜在的膜和蛋白相互作用位点，后者在晶体结构和冷冻电镜重构中均与 Gαq 的 N 端螺旋结合。功能分析表明，远端 CTD 可参与膜靶向，并优化催化核心在膜上的取向，以实现最大的脂质水解速率。
