Receptor-like kinase palmitoylation: resolving a crucial feature of plant cell signalling

调节植物感知-蛋白质棕榈酰化的作用植物不能远离危险，因此必须能够发现环境中的任何潜在威胁或危险变化，并相应地进行适应以生存。植物也是多细胞生物体，其复杂的身体结构由许多特殊的组织和细胞类型组成。组织和维持它们的结构需要严格控制组成植物的各个细胞之间的通信。这些发育和环境信号中的许多是由一组称为受体样激酶(RLKs)的蛋白质检测到的。RLKs是植物中最大的一组蛋白质，占模式生物拟南芥中所有基因的2.5%。RLK检测来自细胞外的信号，如病原体、激素、细胞壁完整性和结构的变化或植物本身产生的图案和发育信号。这些信号通过细胞膜传递，启动细胞内反应，如改变基因活性、改变细胞分裂和分化、修改细胞壁或产生化学物质来抵御病原体。因此，了解RLK信号是如何调控的对植物生物学的各个方面都是至关重要的。每个RLK都检测到不同的信号，并响应与特定蛋白质伙伴结合的信号来启动适当的信号过程。当RLK相互作用时，它们通过一个称为翻译后修饰的过程相互改变。翻译后修饰通常涉及在蛋白质结构中的特定氨基酸上添加或移除小分子，如磷酸基团，以改变其活性，改变它可以与哪些蛋白质相互作用，促进其降解或改变蛋白质在细胞中的位置。RLKs的两个翻译后修饰被很好地理解：磷酸化和泛素化。RLK的磷酸化发生在RLK与其信号伙伴的信号感知和相互作用之后，通常导致信号的激活。泛素化通常会导致RLK被降解，从而停止进一步的信号传递。我最近发现了一种全新的RLK翻译后修饰，这对于它们正确的信号传递是必不可少的。这种修饰被称为棕榈酰化。我发现，未受刺激的RLK是棕榈酰化的，但当它们检测到相关信号时，它们的棕榈酰化状态迅速下降。我们目前尚不清楚RLK信号通路去棕榈酰化的原因，也不知道它与RLK信号转导中的其他事件有关。这项建议试图回答这些问题，并表征这种新的和重要的因素控制植物对细胞外信号做出反应的主要方法的作用。我们还将确定去棕榈酰化RLK所需的酶，以了解这一过程是如何调节的。对RLK功能的更多了解将有助于我们了解植物如何调节对威胁、环境问题的反应，以及它们如何调节它们的发育。这些信息可用于作物育种和发展计划，以引入或改进植物所需的性状，并提供对植物如何对特定环境做出反应的更多洞察力。有趣的是，植物RLK与哺乳动物免疫系统用来检测病原体、激活和增强免疫以及调节炎症的Toll样受体和白细胞介素型受体有关。我最近发现，这些受体的调节方式与植物的RLK一样，这意味着我在植物中所获得的信息可以帮助理解人类的免疫系统调节。

Regulating plant perception - the role of protein palmitoylationPlants are unable to move away from danger and must therefore be able to detect any potential threat or dangerous change in the environment and adapt accordingly to survive. Plants are also multicellular organisms with complex body plans composed of many specialized tissue and cell types. Organising and maintaining their structure requires tightly regulated communication between the individual cells making up the plant. Many of these developmental and environmental signals are detected by a group of proteins called receptor-like kinases (RLKs). RLKs are the largest group of proteins in plants, accounting for 2.5% of all the genes in the model organism Arabidopsis thaliana. RLKs detect signals from outside of the cell such as pathogens, hormones, changes in the integrity and structure of the cell wall or patterning and developmental signals produced by the plant itself. These signals are transmitted across the cell membrane to start intracellular responses such as altering gene activity, changing cell division and differentiation, modifying the cell wall or production of chemicals to fight off pathogens. Understanding how RLK signaling is regulated is therefore critical to all aspects of plant biology.Each RLK detects a different signal and in response to signals bind to specific protein partners to start the appropriate signaling processes. When RLKs interact they alter each other through a process known as post-translational modification. Post-translational modification usually involves the addition or removal of small molecules, such as phosphate groups, to specific amino acids in a proteins structure to alter its activity, change which proteins it can interact with, promote its degradation or change where in the cell the protein is found. Two post-translational modifications of RLKs are fairly well understood; phosphorylation and ubiquitination. Phosphorylation of RLKs occurs after signal perception and interaction of the RLK with its signaling partner, and generally causes activation of signaling. Ubiquitination usually results in the RLK being degraded to stop further signaling. I have recently discovered an entirely novel post-translation modification of RLKs that is essential for their correct signaling. This modification is called palmitoylation. I have found that unstimulated RLKs are palmitoylated but when they detect a relevant signal their palmitoylation state rapidly decreases. We currently don't know why RLKs are de-palmitoylated or when it happens in relation to other events in RLK signaling. This proposal seeks to answer these questions and characterize the role of this novel and important factor controlling plants primary method of responding to extracellular signals. We will also identify the enzymes required to de-palmitoylate RLKs to understand how this process is regulated.This greater knowledge of RLK function will help us to understand how plants regulate responses to threats, environmental problems and how they regulate their development. This information can be used in crop breeding and development programs to introduce or improve desired traits in plants and provide more insight into how plants will respond to particular circumstances. Interestingly plant RLKs are related to the Toll-like and interleukin receptors used by mammalian immune systems to detect pathogens, activate and enhance immunity and regulate inflammation. I have recently shown that these receptors are regulated in the same way as plant RLKs meaning that the information from my plant work can be able to help understand immune system regulation in humans.