Making small talk: Using chemistry to send messages across cell membranes

细胞膜是一个屏障，阻止外部化学物质进入细胞。因此，为了与周围的世界交流，细胞在其细胞膜中使用多纳米长的“纳米器件”。这些“纳米器件”，G蛋白偶联受体（GPCR），是一类介导细胞信号转导（通信）的跨膜蛋白，这是一项至关重要的任务，使它们成为药物化学的关键目标。当外部配体结合到其外部时，GPCR传递信号，这诱导跨膜结构域的构象变化，然后触发细胞内的消息释放（通过酶级联）。能够跨膜传递信息的完全人工分子的开发将带来许多令人兴奋的机会（参见Nature Chemistry社论：“Sending a message to the other side”http：//www.nature.com/articles/nchem.2776）。其中包括一种新型的合成生物学，新的信号通路可能会“短路”天然信号网络，使细胞对不寻常的刺激敏感。我们已经表明，由氨基异丁酸（Aib）组成的折叠体（折叠的低聚物）对人工信号转导具有特别的前景。这些折叠成螺旋的寡聚体具有细长的形状，其对N末端的结合事件非常敏感，允许结合信息可以在几纳米内传递。1我们已经使用这种螺旋中继来创建光可切换的Aib折叠体，其能够将光化学信息传递到膜深处，最近，我们开发了一种折叠体，它可以从外部配体传递结合信息，在这个项目中，我们将在细胞环境中应用这类令人兴奋的分子。带有新荧光报告基团的Aib折叠体将被化学合成，随后将研究它们在囊泡和活细胞膜中的构象和螺旋度转换。然后将信号传导机制与酶活性联系起来，使用一系列蛋白酶和酯酶将非结合或非活性信号转化为信号传导分子。该项目将联合收割机细胞生物学、工业生物技术和合成化学三个领域的不同技能，并在后两个领域的核心技能基础上增加跨学科培训。它与BBSRC的“工业生物技术的新战略方法”特别是“开发新的生物催化实体和途径的创新方法”保持一致;我们的目标是开发与生物催化接口的合成细胞信号传导途径。项目培训将实现BBSRC的几个赋能主题，特别是“新的工作方式”。参考文献：[1] Brown，R.一、Diemer，V.;韦伯，S. J.道：Clayden，J. Nature Chem.2013，5，853. [2]De Poli，M.; Zawodny，W.; Quinonero，O.; Lorch，M.; Webb，S.J.; Clayden，J. Science 2016，352，575. [3]Lister，F. G.一、Le Bailly，B. A. F.地;韦伯，S. J.道：Clayden，J. Nature Chem. 2017，9，420.

The membrane is a barrier that prevents external chemicals from entering cells. So to communicate with the world around them, cells use multinanometre-long "nanodevices" in their membranes. These "nanodevices", G-protein-coupled receptors (GPCRs), are a class of transmembrane protein that mediates signal transduction (communication) by the cell, a crucial task that makes them key targets for medicinal chemistry. GPCRs transmit a signal when an external ligand binds to their exterior, which induces conformational changes in the transmembrane domains, then triggers the release of a message within the cell (via an enzymatic cascade). The development of completely artificial molecules that can transmit messages across membranes would lead to many exciting opportunities (see Nature Chemistry editorial: "Sending a message to the other side" http://www.nature.com/articles/nchem.2776). These include a new type of synthetic biology where new signalling pathways might 'short-circuit' natural signalling networks, making cells sensitive to unusual stimuli. We have shown that foldamers (folded oligomers) composed of aminoisobutyric acid (Aib) have particular promise for artificial signal transduction. These oligomers, which fold into helices, have an elongated shape that is very sensitive to binding events at their N-terminus, allowing binding information can be relayed over several nanometres.1 We have used this helical relay to create light-switchable Aib foldamers able to transmit photochemical information deep into membranes, in a manner reminiscent of rhodopsin.2 Most recently we developed a foldamer that transmitted binding information from an external ligand (Leu enkephalin) several nanometres into a membrane.3 In this project, we will apply this exciting class of molecule in a cellular context. Aib foldamers that bear new fluorescent reporter groups will be chemically synthesised, which will be followed by studies of their conformation and helicity switching in the membranes of vesicles and living cells. The signalling mechanism will be then linked to enzymatic activity, with a series of proteases and esterases used to transform non-binding or non-active signals into signalling molecules. If successful, this project would produce for the first time artificial communication between exterior catalytic reactions and the interior of living cells.This project will combine three areas with distinct skillsets, namely cell biology, industrial biotechnology and synthetic chemistry, adding interdisciplinary training to core skills in the latter two areas. It aligns with the BBSRC's "New strategic approaches to Industrial Biotechnology" especially "Innovative approaches to develop new biocatalytic entities and pathways"; we aim to develop synthetic cell signalling pathways that interface with biocatalysis. Project training will fulfil several BBSRC enabling themes, especially "new ways of working". References: [1] Brown, R. A.; Diemer, V.; Webb, S. J.; Clayden, J. Nature Chem. 2013, 5, 853. [2] De Poli, M.; Zawodny, W.; Quinonero, O.; Lorch, M.; Webb, S.J.; Clayden, J. Science 2016, 352, 575. [3] Lister, F. G. A.; Le Bailly, B. A. F.; Webb, S. J.; Clayden, J. Nature Chem. 2017, 9, 420.