Assembly and Function of the Yeast Spore Wall

描述（由申请人提供）：芽殖酵母酿酒酵母（S. cerevisiae）孢子形成过程中孢子壁的新生形成为真菌细胞壁组装的研究提供了一个强大的、易于处理的模型。本基金的重点是阐明孢子壁外两层的结构和组装机制。这两层由壳聚糖多糖和多酚二酪氨酸组成，营养细胞中没有这两层，使孢子能够抵抗各种环境胁迫。重要的是，尽管壳聚糖和二酪氨酸不存在于出芽酵母的营养细胞壁中，但它们存在于许多致病真菌（如白色念珠菌）的细胞壁中。在哺乳动物细胞外基质中没有发现壳聚糖和二酪氨酸，这意味着可能会发现特异性抑制真菌细胞壁组装而不影响哺乳动物细胞的药物。出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。这项资助的实验分为三个相互关联的目标：(1)定义外孢子壁的组成和结构，阐明这些成分被合成并纳入孢子壁的生物合成途径；(2)详细阐述我们的研究表明，营养细胞中糖基化所必需的脂质醇在协调外孢子壁形成中具有新的作用；(3)应用我们从孢子壁组装研究中获得的知识来定义构建白色念珠菌细胞壁中壳聚糖/二酪氨酸模块所必需的保守遗传工具包。

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.