Metabolomic Profiling of Membrane Lipids and their Compositional Dynamics in Plant Stress Responses

膜脂由不同的分子组成，其组成因膜而异。此外，膜脂成分也会随着内外信号的变化而改变。此外，在膜内，可能存在具有不同脂质成分和特定功能的微域。然而，人们并不了解这些不同的成分及其动力学是如何产生的，以及它们在细胞中的功能是什么。本项目的目的是利用代谢组学方法来确定细胞膜脂质组成，并了解膜脂组成动态在植物对逆境反应中的调节和作用。建立了一种基于电喷雾电离串联质谱仪(ESI-MS/MS)的高灵敏方法。ESI-MS/MS将被用于描述温度和干旱胁迫下拟南芥植物膜脂分子的种类和组成动态。为了了解脂质变化是如何调节的，这个项目将研究参与产生膜脂成分动态的酶。不含磷脂酶D各种异构体的拟南芥品系将在分析中发挥重要作用。此外，还将对硬脂酰-ACP去饱和酶缺陷的防御突变体SSI2及其抑制系的脂类分子物种进行分析，以确定脂类组成与防御反应变化的关系。将完整的脂谱分析与对产生成分变化的机制的细胞分析相结合的能力，应该会产生关于细胞机制和代谢物如何以动态方式在细胞对不断变化的环境的反应中相互作用的新信息。膜脂是重要的生物成分，为生物膜提供结构骨架，也是产生调节细胞和生物功能的第二信使的重要资源。膜脂由不同的分子组成，其组成因膜而异。脂肪成分会随着内部和外部信号的变化而变化。然而，人们并不了解这些不同的成分及其动力学是如何产生的，以及它们在细胞中的功能是什么。本项目将建立一种基于电喷雾电离串联质谱仪的高效方法，并利用它来确定细胞膜脂组成以及膜脂组成变化在植物对胁迫反应中的作用。对膜脂及其代谢物的广泛剖析将产生关于细胞机械和代谢物如何以动态方式在细胞对不断变化的环境的反应中相互作用的空前信息。

Membrane lipids comprise diverse molecular species, and their composition differs from membrane to membrane. In addition, membrane lipid composition changes in response to internal and external cues. Furthermore, within a membrane, there may be microdomains with distinct lipid constituents and particular functions. However, it is not understood how these distinct compositions and their dynamics are generated and what their functions are in the cell. The objectives of this project are to use a metabolomic approach to determine cellular membrane lipid composition and to understand the regulation and role of membrane lipid compositional dynamics in plant responses to stresses. A highly sensitive approach based on electrospray ionization tandem mass spectrometry (ESI-MS/MS) will be established. ESI-MS/MS will be employed to profile membrane lipid molecular species and to determine the compositional dynamics in Arabidopsis plants undergoing temperature and drought stresses. To understand how lipid changes are regulated, this project will investigate enzymes involved in generating the membrane lipid compositional dynamics. Arabidopsis lines, abrogated of various isoforms of phospholipase D, the major lipolytic enzyme family, will be instrumental in the analysis. In addition, lipid molecular species of the defense mutant ssi2 that is defective in stearoyl-ACP desaturase and its suppressor lines will be profiled to determine the relationship between lipid composition and alterations in defense responses. The capability to combine full lipid profiling with cellular analysis of the machinery that generates compositional changes should yield new information on how cellular machinery and metabolites interact in a dynamic manner in the cellular response to changing environments. Membrane lipids are vital biological constituents, providing structural backbones for biological membranes and crucial resources for producing second messengers in regulating cellular and organismal functions. Membrane lipids comprise diverse molecular species, and the composition differs from membrane to membrane. The lipid composition changes in response to internal and external cues. However, it is not understood how these distinct compositions and their dynamics are generated and what their functions are in the cell. This project will establish a highly effective approach based on electrospray ionization tandem mass spectrometry and use it to determine cellular membrane lipid composition and the role of membrane lipid compositional changes in plant responses to stresses. Extensive profiling of membrane lipids and their metabolites will yield unprecedented information on how cellular machinery and metabolites interact in a dynamic manner in the cellular response to changing environments.