Analysis of the spatial distribution of the key components of the HOG signaling pathway, TcsC and Ypd1, and its impact on their function in the pathogenic mold Aspergillus fumigatus.

高渗透压甘油（HOG）途径特别有趣，首先，作为真菌信号级联的范例，其次，因为它的传感激酶TcsC代表了新的抗真菌治疗的有吸引力的靶标结构。我们的目的是研究HOG通路初始部分的空间组织，即所谓的双组分磷接力，并确定其对各自蛋白质功能的影响，例如它们对高渗胁迫组织适应性反应的能力。我们的初步结果显示了烟曲霉HOG双组分磷接力的两个关键组分TcsC和Ypd1的新颖和意想不到的定位模式。这使我们提出了一个新的假设，而该项目旨在验证我们的概念：在环境条件下，传感器激酶TcsC驻留在细胞核中，并在激活后易位到细胞质中，这一事实强烈暗示了曲霉在细胞核中感知高渗应激。我们假设这发生在核膜上，涉及一种尚未表征的烟曲霉太阳结构域蛋白，该蛋白反过来被认为是连接核膜和细胞骨架的结构的一部分。如果正确的话，这将建立一个全新的丝状真菌如何感知高渗胁迫的模型。在这个项目中，我们还将定义潜在的TcsC多聚对其功能和在细胞核和细胞质之间穿梭的影响。最后，我们将确定所观察到的活化的Ypd1从细胞质到细胞核的易位的功能相关性，并定义Ypd1的相关结构域/基序。

The High Osmolarity Glycerol (HOG) pathway is particular interesting, firstly, as a paradigm for a fungal signaling cascade and secondly, because its sensing kinase TcsC represents an attractive target structure for new antifungal therapies. Our aim is to study the spatial organization of the initial part of the HOG pathway, the so-called two-component phosphorelay, and to define its impact on the function of the respective proteins, e.g. their ability to organize an adaptive response to hyperosmotic stress. Our preliminary results show novel and unexpected localization patterns for two key components of HOG two-component phosphorelay in A. fumigatus, TcsC and Ypd1. This led us to a new hypothesis, and the proposed project aims to verify our concept:The fact that the sensor kinase TcsC resides in the nucleus at ambient conditions and translocates to the cytoplasm upon activation provides a strong hint that Aspergillus senses hyperosmotic stress in the nucleus. We hypothesize that this takes place at the nuclear membrane and involves a yet uncharacterized A. fumigatus SUN-domain protein that in turn is assumed to be part of a structure that connects the nuclear membrane to the cytoskeleton. If correct, this would establish a completely new model of how filamentous fungi sense hyperosmotic stress. In this project, we will also define the impact of a potential TcsC multimerization on its function and shuttling between the nucleus and the cytoplasm. Finally, we will determine the functional relevance of the observed translocation of activated Ypd1 from the cytoplasm to the nucleus and define the relevant domains/motifs of Ypd1.