小柯机器人

英国牛津大学Carol V. Robinson等研究人员合作通过天然膜捕捉到视紫红质受体信号级联。2022年4月6日，国际知名学术期刊《自然》在线发表了这一成果。

研究人员使用质谱法直接从天然圆盘膜的碎片中探测了典型的A类G蛋白偶联受体（GPCR），即视紫红质。研究人员监测了暗适应的视紫红质向视蛋白的实时光转化，描述了视网膜的异构化和水解步骤，并进一步表明，该反应在其天然膜中比在去垢剂胶束中要慢很多。考虑到与视紫红质一起喷出的脂质，研究人员证明了视紫红质可以通过光异构化的视网膜-脂质共轭物在膜中再生，并且研究人员提供了证据表明在信号传递过程中，视紫红质与不饱和长链磷脂酰胆碱的关联度增加。

为了捕捉信号级联的次要步骤，研究人员监测到光通过失去GDP来激活转导蛋白（G_t），生成中间的apo-三聚体G蛋白，并观察到Gα_t-GTP亚单位与PDE6相互作用，水解环状GMP。研究人员还展示了视紫红质靶向化合物如何通过视紫红质-视蛋白和转导蛋白信号通路刺激或抑制信号传导。这些结果不仅揭示了局部脂质对视紫红质信号和再生的影响，而且使研究人员能够提出在局部膜环境中发现GPCR药物的范式。

据了解，GPCR是细胞表面的受体，对各种刺激作出反应，诱导细胞膜上的信号传导途径。最近的进展已经产生了关键中间体的原子结构和脂质在信号传导中的作用。然而，实时捕捉野生型受体的信号事件，通过局部膜到其下游效应器，仍然是难以实现的。

附：英文原文

Title: Capturing a rhodopsin receptor signalling cascade across a native membrane

Author: Chen, Siyun, Getter, Tamar, Salom, David, Wu, Di, Quetschlich, Daniel, Chorev, Dror S., Palczewski, Krzysztof, Robinson, Carol V.

Issue&Volume: 2022-04-06

Abstract: G protein-coupled receptors (GPCRs) are cell-surface receptors that respond to various stimuli to induce signalling pathways across cell membranes. Recent progress has yielded atomic structures of key intermediates1,2 and roles for lipids in signalling3,4. However, capturing signalling events of a wild-type receptor in real time, across a native membrane to its downstream effectors, has remained elusive. Here we probe the archetypal class A GPCR, rhodopsin, directly from fragments of native disc membranes using mass spectrometry. We monitor real-time photoconversion of dark-adapted rhodopsin to opsin, delineating retinal isomerization and hydrolysis steps, and further showing that the reaction is significantly slower in its native membrane than in detergent micelles. Considering the lipids ejected with rhodopsin, we demonstrate that opsin can be regenerated in membranes through photoisomerized retinal–lipid conjugates, and we provide evidence for increased association of rhodopsin with unsaturated long-chain phosphatidylcholine during signalling. Capturing the secondary steps of the signalling cascade, we monitor light activation of transducin (Gt) through loss of GDP to generate an intermediate apo-trimeric G protein, and observe GαtGTP subunits interacting with PDE6 to hydrolyse cyclic GMP. We also show how rhodopsin-targeting compounds either stimulate or dampen signalling through rhodopsin–opsin and transducin signalling pathways. Our results not only reveal the effect of native lipids on rhodopsin signalling and regeneration but also enable us to propose a paradigm for GPCR drug discovery in native membrane environments.

DOI: 10.1038/s41586-022-04547-x

Source: https://www.nature.com/articles/s41586-022-04547-x

Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
投稿链接：http://www.nature.com/authors/submit_manuscript.html