Assembly and Function of the Yeast Spore Wall

所有细胞都被细胞外基质包围，为细胞提供物理支持和保护。在多细胞生物体中，来自单个细胞的胞外基质结合在一起形成更大的结构，为有机体的身体提供支架。因此，重要的是要了解细胞外基质是如何构建和连接的。在酵母中形成的孢子壁是一种分层的多细胞胞外基质，它的形成为研究胞外基质的组装提供了一个很好的模型系统。对一系列孢子壁形成缺陷突变株的初步鉴定提供了孢子壁组装途径的轮廓。这项初步工作将通过进一步研究不同的孢子壁组装基因在促进孢子壁形成中的作用来扩大。催化主要孢子壁多糖形成的β-葡聚糖和甲壳素合成产物的定位和活性将在野生型细胞和突变细胞中进行研究，以寻找可能的调控基因。此外，还将探索AMA1基因的作用分子机制，该基因将退出减数分裂与孢子壁形成的开始联系在一起。最后，孢子壁的外层既允许孢子抵抗环境压力，又通过桥梁将单个孢子连接在一起。将研究与这些层组装有关的蛋白质的靶向和锚定到孢子壁的情况。此外，还将分析一组在外孢子壁组装中存在轻微缺陷的突变株，以确定与获得对特定胁迫的抗性有关的基因。综上所述，这些研究将加深我们对孢子壁形成的分子机制的理解，这将反过来为在其他生物中组装细胞外基质的策略提供洞察力。

All cells surround themselves with an extracellular matrix that provides both physical support and protection for the cell. In multicellular organisms the extracellular matrices from individual cells combine to form much larger structures that provide the scaffolding for the body of the organism. It is important, therefore, to understand how extracellular matrices are constructed and connected. The formation of the spore wall, a stratified, multicellular extracellular matrix, in the yeast Saccharomyces cerevisiae provides an excellent model system to study the assembly of extracellular matrices. An initial characterization of a collection of mutants defective in spore wall formation has provided an outline of the pathway of spore wall assembly. This initial work will be expanded by further studies on the role of the different spore wall assembly genes in promoting formation of the wall. The localization and activity of the beta-glucan and chitin syntheses, which catalyze the formation of the major spore wall polysaccharides, will be investigated both in wild type cells and in cells mutant for putative regulatory genes. Additionally, the molecular mechanism of action of the AMA1 gene, which links the exit from meiosis to the onset of spore wall formation will be explored. Finally, the outer layers of the spore wall both allow the spore to resist environmental stress and connect individual spores together through bridges. The targeting and anchoring to the spore wall of proteins involved in the assembly of these layers will be investigated. Also, a collection of mutants with modest defects in outer spore wall assembly will be analyzed to define genes involved in acquisition of resistance to specific stresses. In sum, these studies should deepen our understanding of the molecular mechanisms of spore wall construction, which will in turn provide insight into the strategies of extracellular matrix assembly in other organisms.