MOLECULAR GENETICS OF YEAST SEXUAL AGGLUTININS

在酵母酿酒酵母中，交配过程中的细胞-细胞接触是 介导的细胞表面粘附糖蛋白，称为α-和α- 凝集素，由α和α交配型细胞表达， 分别预测α-凝集素具有类似于 哺乳动物细胞粘附蛋白的免疫球蛋白超家族， 这表明，阐明粘附蛋白相互作用的酵母将 对高等真核生物也有影响。拟议的一个重要目标是 研究是表征粘附蛋白相互作用。诱变 的α-凝集素粘附结构域，根据提供的信息， 一种结构模型，正被用来确定参与的残基 粘附和蛋白质的结构。这种方法将是 延伸至α-凝集素粘附亚基。的特异性 高等真核生物中的粘附蛋白相互作用对于 特异性病毒-细胞、细胞-细胞和细胞-细胞外基质 交互.其他种类的芽殖酵母表达凝集素， 与S.酿酒酵母凝集素;然而， 凝集素相互作用显示种特异性。的克隆 从酵母S.克鲁维里将促进 粘附蛋白的结构模拟和物种研究 的特异性杂交S.酿酒酵母/S.将构建kluyveri基因， 并测试其功能和特异性， 并筛选特异性改变突变体以鉴定残基 涉及到特异性。这项研究的最终目标包括： 凝集素细胞壁定位机制的分析。 α-凝集素通过连接转运到质膜， 一种糖基磷脂酰肌醇锚，在此之后，一种新的机制起作用 转移到细胞壁上α-凝集素细胞的性质 壁连接将被表征，并且α-凝集素序列 将确定参与这一目标确定机制的人员。此外，本发明还提供了一种方法， 将进行突变体筛选以鉴定与此相关的酶。 新机制这种α-半乳糖苷酶与细胞壁结合的机制 凝集素与一般的细胞壁甘露糖蛋白定位有关。 因为其他真菌的细胞壁结构与酵母相似， 探讨了S.酿酒酵母 可能导致开发治疗药物， 重要真菌

Cell-cell contact during mating in the yeast Saccharomyces cerevisiae is mediated by cell surface adhesion glycoproteins, called a- and alpha- agglutinin, which are expressed by cells of a and alpha mating type, respectively. Alpha-agglutinin is predicted to have a structure similar to the immunoglobulin superfamily of mammalian cell adhesion proteins, suggesting that elucidation of adhesion protein interactions in yeast will have implications for higher eukaryotes. An important goal of the proposed research is to characterize the adhesion protein interactions. Mutagenesis of the alpha-agglutinin adhesion domain, based on information provided by a structural model, is being used to identify residues involved in adhesion and in the structure of the protein. This approach will be extended to the alpha-agglutinin adhesion subunit. The specificity of adhesion protein interactions in higher eukaryotes is critical for specific viral-cell, cell-cell, and cell-extracellular matrix interactions. Other species of budding yeast express agglutinins that share biochemical features with the S. cerevisiae agglutinins; however agglutinin interactions show species specificity. The cloning of agglutinin structural genes from the yeast S. kluyveri will facilitate structural modeling of the adhesion proteins and studies of species specificity. Hybrid S. cerevisiae/S. kluyveri genes will be constructed and tested for function and specificity, and the genes will be mutagenized and screened for change-of-specificity mutants to identify residues involved in specificity. The final goal of the proposed research involves an analysis of the mechanism of cell wall localization of the agglutinins. Alpha-agglutinin is transported to the plasma membrane through linkage to a glycosyl phosphatidylinositol anchor, after which a novel mechanism acts to transfer it to the cell wall. The nature of the alpha-agglutinin-cell wall linkage will be characterized, and the alpha-agglutinin sequences involved in this targeting mechanism will be identified. In addition, mutant screens will be undertaken to identify enzymes involved in this novel mechanism. This mechanism of cell wall attachment of alpha- agglutinin is implicated in general cell wall mannoprotein localization. Because cell wall structure in other fungi is similar to yeast, investigation of the mechanism of cell wall biogenesis in S. cerevisiae may lead to the development of therapeutic agents against medically important fungi.