Structural and biochemical studies on the mechanism of CO2-sensing in the virulence of pathogenic fungi

二氧化碳（CO2）可以作为信号分子，例如使蚊子能够找到猎物。人类病原真菌C.白色念珠菌和C.在从自然环境中生长（~ 0.03%CO2）转变为宿主中毒性生长（~ 5%CO2）的过程中，新生虫。生物体如何检测和响应二氧化碳的机制在很大程度上是未知的。然而，最近，腺苷酸环化酶和碳酸酐酶被确定为真菌CO2传感系统的组成部分。真菌腺苷酸环化酶被发现是敏感的碳酸氢盐，由碳酸酐酶催化的反应的产物。在某些条件下，敲除任一种酶都可以防止真菌发病，这表明所涉及的酶是抗真菌药物的靶标。我们计划通过使用生物化学方法和蛋白质晶体学来研究这个信号系统。我们将确定与各种配体复合的真菌酶的结构。我们计划利用其独特的分子特性，以结构为基础的高度特异性的抑制剂，这将用于对真菌发病机制的生理研究的发展。我们还将进一步研究腺苷酸环化酶的调节机制的细节？类碳酸酐酶，特别是预期的两种酶的相互作用。这项工作应该揭示这种信号通路的独特功能，可以通过新的疗法来靶向。

Carbon dioxide (CO2) can act as a signalling molecule and e.g. enables mosquitos to find their prey. A CO2-sensing system is also involved in the human-pathogenic fungi C. albicans and C. neoformans in switching from growth in a natural environment (~0.03 % CO2) to virulent growth in the host (~5 % CO2). The mechanisms how organisms detect and respond to CO2 are largely unknown. Recently, however, an adenylyl cyclase and a carbonic anhydrase were identified as components of the fungal CO2-sensing system. The fungal adenylyl cyclases were found to be sensitive to bicarbonate, the product of the reaction catalyzed by carbonic anhydrases. Knocking out either enzyme prevents fungal pathogenesis under certain conditions suggesting the enzymes involved as targets for anti-fungal drugs. We plan to study this signalling system by using biochemical methods and protein crystallography. We will determine structures of the fungal enzymes in complex with various ligands. We plan to exploit their unique molecular characteristics for the structure-based development of highly specific inhibitors which will be used for physiological studies on fungal pathogenesis. We will also study further mechanistic details of adenylyl cyclase regulation by ¿-class carbonic anhydrases, especially the anticipated interaction of the two enzymes. This work should reveal unique features of this signalling pathway which could be targeted by novel therapies.