Martin-Ramirez Sergio, Stouthamer Jente, Smakowska-Luzan Elwira
Laboratory of Biochemistry, Wageningen University and Research, Wageningen, The Netherlands.
Plant J. 2025 Apr;122(2):e70176. doi: 10.1111/tpj.70176.
Over the past few decades, significant advancements have been made in understanding how plasma-membrane localised receptor kinases (RKs) detect signals and activate responses to various stimuli. Numerous examples of ligand-induced receptor activation mechanisms and their downstream consequences have been characterised in detail. The crucial role of post-translational modifications (PTMs), such as the phosphorylation of receptor kinases, has been demonstrated concerning different cellular responses. Given the diverse structures and architectures of the extracellular domains (ECDs) of RKs, it is probable that various forms of PTMs also play an essential role in receptor activation, including cysteine oxidative modifications triggered by reactive oxygen species (ROS). The function of cysteine oxidative modifications as functional redox switches that modulate protein structure and function has been extensively studied across various multicellular organisms. Based on biochemical and structural characteristics, the family of cysteine-rich receptor-like kinases (CRK) emerges as excellent candidates for proteins regulated in a redox-dependent manner. This review provides a concise overview of cysteine's biochemical and structural properties in its role as a molecular redox switch. Drawing on the currently available literature, we describe how cysteine-redox signalling is maintained, particularly in plant cells. We further focus on extracellular ROS perception and the role of CRKs as promising candidates for ROS sensors in Arabidopsis thaliana. We discuss the structural and biochemical properties of CRKs, their involvement in plant growth and defence processes, and our perspective on why CRKs could be key components of the ROS sensing machinery or ROS sensors, especially regarding the dimerization abilities of CRKs. Finally, we highlight the current challenges in identifying and quantifying cysteine oxidative modifications and propose methods for detecting ROS-modified cysteines that may be promising for investigating the role of CRKs in extracellular ROS perception and signalling.
在过去几十年中，我们对质膜定位的受体激酶（RKs）如何检测信号并激活对各种刺激的反应有了重大进展。配体诱导的受体激活机制及其下游后果的众多例子已得到详细表征。翻译后修饰（PTMs）的关键作用，如受体激酶的磷酸化，已在不同细胞反应中得到证实。鉴于RKs细胞外结构域（ECDs）的多样结构和架构，各种形式的PTM可能在受体激活中也起着重要作用，包括活性氧（ROS）引发的半胱氨酸氧化修饰。作为调节蛋白质结构和功能的功能性氧化还原开关，半胱氨酸氧化修饰的功能已在各种多细胞生物体中得到广泛研究。基于生化和结构特征，富含半胱氨酸的类受体激酶（CRK）家族成为以氧化还原依赖性方式调节的蛋白质的优秀候选者。本综述简要概述了半胱氨酸作为分子氧化还原开关的生化和结构特性。借鉴现有文献，我们描述了半胱氨酸氧化还原信号是如何维持的，特别是在植物细胞中。我们进一步关注细胞外ROS感知以及CRKs作为拟南芥中ROS传感器的有前途候选者的作用。我们讨论了CRKs的结构和生化特性、它们在植物生长和防御过程中的参与，以及关于为什么CRKs可能是ROS传感机制或ROS传感器的关键组成部分的观点，特别是关于CRKs的二聚化能力。最后，我们强调了识别和量化半胱氨酸氧化修饰目前面临的挑战，并提出了检测ROS修饰半胱氨酸的方法，这些方法可能有助于研究CRKs在细胞外ROS感知和信号传导中的作用。
