Biological Fusions Conjugations in Yeast

描述（由申请人提供）：本提案的目标是了解酵母到细丝开关和真菌毒力之间的联系。这个开关与真菌细胞周围的分子、葡聚糖和相关的甘露糖蛋白（黏附素）密切相关。对酿酒酵母菌模型系统中丝状结构的分析将指导较难处理的白色念珠菌的研究。两种真菌的基因组编码许多甘露蛋白，赋予独特的粘附特性。这些黏附素是真菌细胞相互作用（絮凝和成丝）、与惰性表面（琼脂和塑料）以及与哺乳动物细胞相互作用所必需的。一种新的反义IME4 RNA在控制粘附素表达中的作用将在两种生物体中确定。tyrosol是一种自动调节分子，在酵母菌形态和丝状形态之间的转换以及真菌与吞噬细胞的相互作用中所起的作用将通过分析其生物合成、感知和信号转导作用来解决。巨噬细胞区分酵母菌和念珠菌的能力可能是由于每种生物表面的β -葡聚糖对巨噬细胞上关键的非听觉真菌受体Dectin-1的可及性不同。初步实验表明，真菌细胞表面β -葡聚糖的不同呈现导致真菌与Dectin-1的不同结合以及巨噬细胞对炎症细胞因子的不同激发。揭示β -葡聚糖或β -葡聚糖结构是关键的问题将通过系统地使用全基因组突变文库来识别β -葡聚糖表达改变的突变体，并使用这些突变体来识别免疫反应来解决。另外的实验旨在确定甘露糖蛋白转运到真菌细胞壁所需的所有基因。我们关于缺氧诱导念珠菌成丝的发现将用于分析低氧胁迫下毒力的重要基因。在我们的分析中发现的基因是开发对抗真菌的新疗法的潜在目标，真菌对那些正在接受化疗和患有艾滋病的人来说是如此具有破坏性。

DESCRIPTION (provided by the applicant): The goal of this proposal is to understand the connection between the yeast to filament switch and fungal virulence. This switch is intimately connected to the molecules that encircle the fungal cell, beta-glucan and the linked mannoproteins (adhesins). The analysis of filamentation in the model system, Saccharomyces cerevisiae will guide the studies in the less tractable pathogen, Candida albicans. The genomes of both fungi encode many mannoproteins that confer unique adherence properties. These adhesins are required for interactions of fungal cells with each other {flocculation and filamentation), with inert surfaces (agar and plastic) and with mammalian cells. The role of a novel antisense IME4 RNA in controlling the expression of the adhesins will be determined in both organisms. The role of tyrosol, an autoregulatory molecule in triggering the switch between the yeast form and the filament form as well as its role in the interaction of fungi with phagocytic cells will be resolved by analysis of its biosynthesis, perception and role in signal transduction. The ability of macrophages to distinguish between Saccharomyces and Candida is likely to result from differential accessibility of beta-glucan on the surface of each organism to Dectin-1, the key non-opsonic fungal receptor on macrophages. Preliminary experiments show that differential beta-glucan presentation on the fungal cell surface leads to differential binding of fungi to Dectin-1 and to different elicitation of inflammatory cytokines from macrophages. The question of whether the unmasking of beta-glucan or the structure of beta-glucan is key will be resolved by systematic use of whole genome mutant libraries to identify mutants with altered beta-glucan presentation and the use of those mutants to identify the immune response. Additional experiments are designed to identify all the genes required for the mannoproteins to transit to the fungal cell wall. Our finding that hypoxia induces filamentation in Candida will be used to analyze the genes important for virulence under low oxygen tensions. The genes uncovered in our analyses are potential targets for the development of novel therapeutics against fungi, which are so devastating to those undergoing chemotherapy and afflicted with AIDS.