Role of Cellulose and Protein in the Dictyostelium Spore Coat

小行星9316897 网囊藻孢子衣含有约一半的多糖，包括纤维素和半乳糖醛酸，以及约一半的蛋白质，包括至少7种不同的蛋白质种类。 涂层分两个阶段组装。 首先，预先形成的外壳蛋白和galuran被分泌，在细胞表面形成一层。 大多数蛋白质在相邻孢子之间交换，表明在分泌后在细胞外发生组装。 一种蛋白质。其独特之处在于其不交换，就好像其锚定或引发涂层组装一样。 在第二阶段，纤维素积累，蛋白质进一步组织。 纤维素传统上被认为是结构和功能的主要决定因素。 PI提出了两个假设来研究蛋白质和多糖的相对贡献。 假设一表明，蛋白质在启动外套的组装中起着关键作用，因此如果没有SP 86等蛋白质的必要基团，外套的蛋白质部分将不会组装或不会附着在质膜上，并且积累的东西将不会正确定位。 假设II表明，在不存在纤维素的情况下，仍然会形成显微镜可检测到的和可沉积的蛋白质假衣。 该提案有三个目标：1）破坏孢子外壳蛋白SP 87的基因; 2）分离孢子外壳蛋白SP 86的基因并破坏它;和3）破坏UDPGPP 2的基因，并研究该基因对外壳结构的影响。 孢子衣和其他细胞外基质保护封闭的细胞免受不利环境的影响。 虽然这些矩阵中的一些组成部分是部分已知的，但这些部分如何组合在一起，它们的比例如何调节，以及保护如何发生的知识主要来自推测。 细胞黏菌Dictyostelium的孢子衣是在分子水平上研究基质的良好系统，因为它简单，它可以大量分离并以高纯度分离，其用于多糖合成的许多蛋白质和酶的基因已经被克隆并可以被破坏，并且存在用于组合物的良好测定。涂层的结构和功能。 这项研究的结果将增强我们对植物和真菌细胞壁组装的认识。 ***

9316897 West Dictyostelium spore coats contain about one -half polysaccharide, including cellulose and galuronan, and about one half protein, including at least 7 different protein species. The coat is assembled in two phases. First, preformed coat proteins and the galuran are secreted, forming a layer at the cell surface. Most of the proteins exchange between neighboring spores, indicating that assembly occurs extracellularly after secretion. One protein. is unique in that it is not exchanged, as if it anchors or initiates coat assembly. During the second phase cellulose accumulates, and the proteins organize further. Cellulose has traditionally been considered to be the primary determinant of structure and function. The PI proposes two hypotheses to investigate the relative contribution of proteins and polysaccharides. Hypothesis I suggests that proteins play a critical role in initiating assembly of the coat so that the absence of essential groups of proteins such as SP86, the protein part of the coat will not assemble or will not be attached to the plasma membrane, and what accumulates will not be positioned correctly. Hypothesis II suggests that in the absence of cellulose, a microscopically detectable and sedimentable protein pseudocoat will still form.. The proposal has three aims: 1) To disrupt the gene for the spore coat protein SP87; 2) To isolate the gene for the spore coat protein SP86 and disrupt it; and 3) To disrupt the gene for UDPGPP2, and to investigate the effect of this gene on coat structure. %%% Spore coats and other extracellular matrices protect enclosed cells from unfavorable environments. Although the constituents of a number of these matrices is partially known, knowledge of how this parts fit together, how their proportions are regulated, and how protection occurs is largely derived by speculation. The spore coat of the cellular slime mold Dictyostelium is a good system to study matrices at a molecular level, becaus e it is simple it can be isolated in bulk and in high purity, the genes for a number of its proteins and enzymes for polysaccharide synthesis have been cloned and can be disrupted, and good assays exist for the composition. structure and function of the coat. The results of this investigation will enhance our knowledge about the assembly of walls in plant and fungal cells. ***