Channeling sugar substrates into specific cell wall products through different nucleotide sugar transporters

所有的植物细胞都被细胞壁包围：一种以多糖为基础的细胞外基质，为植物细胞提供机械支持和保护。植物细胞壁也是巨大的可再生生物资源，提供膳食纤维；棉花、亚麻、纸张和木材等材料；以及生物材料和生物燃料的原料。活性糖，又称核苷酸糖，是所有细胞壁多糖的“积木”。大多数核苷酸糖是在细胞质中产生的，必须通过转运蛋白运输到高尔基体中，以供应在高尔基体内组装多糖的酶。Ebert实验室已经确定了六种转运蛋白(URGT1-6)的特征，这些转运蛋白是将活化的鼠李糖和半乳糖运输到高尔基体合成多糖所必需的。我们推测，这些URGT可能定位于高尔基体的不同膜室(池)，在那里它们可能为合成不同的细胞壁多糖提供底物。麦克法兰实验室已经建立了几种用于蛋白质和多糖的高分辨率亚高尔基定位的技术，我们建议将这些方法应用于URGT家族。通过学生交流和合作实验，这项建议旨在确定不同的URGT是否定位于不同的高尔基体，以及这如何影响细胞壁多糖的合成。了解这些URGT在将细胞壁合成的构建块运输到高尔基体中所起的作用可以提高我们对高尔基体中多糖合成组织的理解，可能为微调生物技术和农业应用中的细胞壁合成开辟新的途径。

All plant cells are surrounded by a cell wall: a polysaccharide-based extracellular matrix that provides mechanical support and protection to plant cells. Plant cell walls are also vast renewable bioresources, supplying dietary fibre; materials like cotton, linen, paper, and wood; and feedstocks for biomaterials and biofuels. Activated sugars, called nucleotide sugars, are the "building blocks" of all cell wall polysaccharides. Most of nucleotide sugars are made in the cytosol and must be transported into the Golgi apparatus via transporters to supply the enzymes that assemble polysaccharides inside the Golgi. The Ebert lab has characterized six of these transporters (URGT1-6) that are required for transport of activated rhamnose and galactose into the Golgi apparatus for polysaccharide synthesis. We hypothesize that these URGTs may be localized to different membrane compartments (cisternae) of the Golgi, where they may supply substrates for synthesis of different cell wall polysaccharides. The McFarlane lab has established several techniques for high-resolution sub-Golgi localization of both proteins and polysaccharides and we propose to apply these approaches to the URGT family. Through student exchanges and collaborative experiments, this proposal aims to determine whether the different URGTs are localized to different Golgi compartments and how this impacts cell wall polysaccharide synthesis. Understanding the roles that each of these URGTs play in transporting the building blocks of cell wall synthesis into the Golgi can improve our understanding of the organization of polysaccharide synthesis within the Golgi apparatus may open new avenues for fine-tuning cell wall synthesis for biotechnological and agricultural applications.