BIOSYNTHESIS OF YEAST CELL WALL BETA 1,6 GLUCAN POLYMERS

酵母细胞壁 β 1,6 葡聚糖聚合物的生物合成

• 批准号: 6386574
• 负责人: CLAUDIA ABEIJON
• 金额: $ 20.75万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-06-01 至 2005-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6386574
• 关键词: Saccharomyces cerevisiae; carbohydrate biosynthesis; cell wall; glucans; glucose transporter; intracellular transport; molecular cloning

DESCRIPTION: (Verbatim from the applicant's description) In yeast and other fungi, cell shape, growth, and cell division depend on the coordinated synthesis and degradation of cell wall components. A quantitatively minor but functionally critical component of the yeast cell wall is the polymer beta-1,6 glucan. This polysaccharide is covalently cross-linked to other cell wall components, such as chitin, 3'-1,3 glucan and mannoproteins. These cross-links stabilize and organize the cell wall. The long-term goal of this project is to investigate the mechanisms by which beta-1,6 glucan is synthesized and associated with other cell wall components. We hypothesize that key aspects of beta-1,6 synthesis differ from those of the more abundant 3'-1,3 glucan polymer. Specifically, the proposed work will examine the hypothesis that beta-1,6 glucan synthesis is initiated in the lumen of the endoplasmic reticulum. Chain elongation and branching occurs in the Golgi apparatus, where the assembled polymers are packaged into secretory vesicles for delivery to the periplasmic space and assembly into the cell wall. In previous work we demonstrated the transport of UDP-glucose, the sugar donor for polymer assembly, into the lumen of the endoplasmic reticulum in Saccharomyces cerevisiae. In order to test our hypothesis we will identify the UDP-glucose transporter gene in yeast and generate a null mutant. Our model predicts that '3-1,6 glucan synthesis, but not 3'-1,3 glucan synthesis, will be prevented in the null mutant. A second, independent, strategy is to determine directly the subcellular sites in which beta-1,6 glucan chains are initiated and extended. This will be accomplished by in vivo radiolabeling experiments in combination with cell fractionation. This work will be facilitated by the use of mutants defective in beta-1,6 glucan synthesis (kre) and secretion (sec). The final approach consists of identifying and characterizing the enzymes that are responsible for synthesis of '3-1,6 glucan. The information derived from these studies will provide important new knowledge on the molecular mechanism of fungal cell wall assembly.

描述：（逐字来自申请人的描述）在酵母和其他 真菌、细胞形状、生长和细胞分裂取决于协调 细胞壁成分的合成和降解。数量虽小但 酵母细胞壁的功能关键成分是聚合物 beta-1,6 葡聚糖。这种多糖与其他细胞壁共价交联 成分，如几丁质、3'-1,3 葡聚糖和甘露糖蛋白。这些交叉链接 稳定并组织细胞壁。该项目的长期目标是 研究 β-1,6 葡聚糖的合成机制 与其他细胞壁成分相关。我们假设以下关键方面 beta-1,6 的合成与更丰富的 3'-1,3 葡聚糖的合成不同 聚合物。具体来说，拟议的工作将检验以下假设： β-1,6 葡聚糖的合成在内质腔中启动 网状结构。链伸长和分支发生在高尔基体中，其中 组装好的聚合物被包装到分泌囊泡中以输送到 周质空间并组装成细胞壁。在之前的工作中我们 证明了 UDP-葡萄糖（聚合物的糖供体）的运输 组装到酵母菌的内质网腔中 酿酒酵母。为了检验我们的假设，我们将鉴定 UDP-葡萄糖 酵母中的转运蛋白基因并产生无效突变体。我们的模型预测 '3-1,6 葡聚糖的合成，但不是 3'-1,3 葡聚糖的合成，将被阻止 无效突变体。第二个独立的策略是直接确定 β-1,6 葡聚糖链起始和延伸的亚细胞位点。 这将通过体内放射性标记实验组合来完成 与细胞分级分离。突变体的使用将促进这项工作 β-1,6 葡聚糖合成 (kre) 和分泌 (sec) 存在缺陷。决赛 该方法包括识别和表征酶 负责合成'3-1,6葡聚糖。从这些信息中得出的信息 研究将为分子机制提供重要的新知识 真菌细胞壁组装。