Assembly and Function of the Yeast Spore Wall

描述(由申请人提供)：在萌芽酵母的孢子形成过程中，孢子壁的从头形成为研究真菌细胞壁组装提供了一个强大的、易处理的模型。这项授权的重点是阐明外两层孢子壁的组装结构和机制。这两层由多糖壳聚糖和多酚二核苷酸组成，营养细胞中不存在这两层，使孢子能够抵抗各种环境压力。重要的是，尽管在萌芽酵母的营养细胞壁中不存在壳聚糖和二氢赖氨酸，但它们存在于许多病原真菌的细胞壁中，如白色念珠菌。在哺乳动物细胞外基质中没有发现壳聚糖和二羟甲基丙氨酸，这意味着可能会发现专门抑制真菌细胞壁组装的药物，而不会影响哺乳动物细胞。发芽酵母孢子壁为研究真菌壁形态发生提供了一个很好的模型系统。这项资助中的实验分为三个相互关联的目的：(1)确定外孢子壁的组成和结构，并阐明这些成分合成和整合到孢子壁的生物合成途径；(2)阐述我们的研究，表明营养细胞糖化所需的一种必需的脂类多糖醇在协调外孢子壁的形成方面具有新的作用；以及(3)应用我们从孢子壁组装研究中获得的知识来定义保守的遗传工具包，该工具包对于构建白色念珠菌细胞壁中的壳聚糖/二羟酪氨酸模块是必不可少的。

DESCRIPTION (provided by applicant): The de novo formation of the spore wall during the process of sporulation in the budding yeast S. cerevisiae provides a powerful, tractable model for the study of fungal cell wall assembly. This grant is focused on elucidating the structure and mechanism of assembly of the outer two layers of the spore wall. These two layers, comprised of the polysaccharide chitosan and the polyphenol dityrosine, are absent from vegetative cells and enable spores to resist a variety of environmental stresses. Importantly, although chitosan and dityrosine are absent from vegetative cell walls in budding yeast they are present in the walls of many pathogenic fungi such as Candida albicans. Chitosan and dityrosine are not found in mammalian extracellular matrices, meaning that drugs may be found that specifically inhibit fungal cell wall assembly without affecting mammalian cells. The budding yeast spore wall provides an excellent model system to study fungal wall morphogenesis. Experiments in this grant are divided into three interrelated aims: (1) define the composition and structure of the outer spore wall and elucidate the biosynthetic pathways by which the components are synthesized and incorporated into the spore wall; (2) elaborate on our studies which have indicated that dolichol, an essential lipid required for glycosylation in vegetative cells, has a novel role in coordinating outer spore wall formation and (3) apply the knowledge gained from our studies of spore wall assembly to define the conserved genetic toolkit essential for construction of the chitosan/dityrosine module of in cell walls of Candida albicans.