Carmona-Salazar Laura, Cahoon Rebecca E, Gasca-Pineda Jaime, González-Solís Ariadna, Vera-Estrella Rosario, Treviño Victor, Cahoon Edgar B, Gavilanes-Ruiz Marina
Dpto. de Bioquímica, Facultad de Química, Conj. E. Universidad Nacional Autónoma de México, UNAM. Cd. Universitaria, Coyoacán. 04510, Cd. de México, México.
Center for Plant Science Innovation & Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, NE 68588-0665, USA.
Plant Physiol. 2021 May 27;186(1):624-639. doi: 10.1093/plphys/kiab064.
Lipid structures affect membrane biophysical properties such as thickness, stability, permeability, curvature, fluidity, asymmetry, and interdigitation, contributing to membrane function. Sphingolipids are abundant in plant endomembranes and plasma membranes (PMs) and comprise four classes: ceramides, hydroxyceramides, glucosylceramides, and glycosylinositolphosphoceramides (GIPCs). They constitute an array of chemical structures whose distribution in plant membranes is unknown. With the aim of describing the hydrophobic portion of sphingolipids, 18 preparations from microsomal (MIC), vacuolar (VM), PM, and detergent-resistant membranes (DRM) were isolated from Arabidopsis (Arabidopsis thaliana) leaves. Sphingolipid species, encompassing pairing of long-chain bases and fatty acids, were identified and quantified in these membranes. Sphingolipid concentrations were compared using univariate and multivariate analysis to assess sphingolipid diversity, abundance, and predominance across membranes. The four sphingolipid classes were present at different levels in each membrane: VM was enriched in glucosylceramides, hydroxyceramides, and GIPCs; PM in GIPCs, in agreement with their key role in signal recognition and sensing; and DRM in GIPCs, as reported by their function in nanodomain formation. While a total of 84 sphingolipid species was identified in MIC, VM, PM, and DRM, only 34 were selectively distributed in the four membrane types. Conversely, every membrane contained a different number of predominant species (11 in VM, 6 in PM, and 17 in DRM). This study reveals that MIC, VM, PM, and DRM contain the same set of sphingolipid species but every membrane source contains its own specific assortment based on the proportion of sphingolipid classes and on the predominance of individual species.
脂质结构会影响膜的生物物理特性，如厚度、稳定性、通透性、曲率、流动性、不对称性和相互交错，从而对膜功能产生影响。鞘脂在植物内膜和质膜中含量丰富，包括四类：神经酰胺、羟基神经酰胺、葡萄糖神经酰胺和糖基肌醇磷酸神经酰胺（GIPC）。它们构成了一系列化学结构，其在植物膜中的分布尚不清楚。为了描述鞘脂的疏水部分，从拟南芥叶片中分离出了18种来自微粒体（MIC）、液泡（VM）、质膜（PM）和抗去污剂膜（DRM）的制剂。在这些膜中鉴定并定量了包括长链碱基和脂肪酸配对的鞘脂种类。使用单变量和多变量分析比较鞘脂浓度，以评估跨膜鞘脂的多样性、丰度和优势。这四类鞘脂在每种膜中的含量不同：VM富含葡萄糖神经酰胺、羟基神经酰胺和GIPC；PM富含GIPC，这与它们在信号识别和传感中的关键作用一致；DRM富含GIPC，这与其在纳米结构域形成中的功能相符。虽然在MIC、VM、PM和DRM中总共鉴定出84种鞘脂种类，但只有34种选择性地分布在这四种膜类型中。相反，每种膜中主要种类的数量不同（VM中有11种，PM中有6种，DRM中有17种）。这项研究表明，MIC、VM、PM和DRM包含相同的鞘脂种类，但每种膜来源都有其基于鞘脂类别比例和单个种类优势的特定组合。
