How does cyclic-di-GMP regulate biosynthesis of a key P. syringae phytotoxin?

假单胞菌是一种广泛分布的植物病原体，在世界范围内造成作物产量损失。植物毒素冠菌素（COR）是由几种烟草疫霉致病变种产生的，在引发植物感染中起重要作用。COR抑制植物免疫，抑制气孔关闭，并诱导受感染组织的褪绿（黄化）。我们最近发现，广泛的细菌信号分子环二GMP（cdG）结合到COR生物合成途径的三种酶。这一发现暗示cdG参与COR调节和控制P.erichingae植物感染。在这个项目中，我们将使用遗传学，生物化学和结构生物学的组合，以确定如何cdG结合控制COR的生物合成在P.dingae。该项目将首先对cdG与COR生物合成酶的结合进行深入的生化分析。cdG和每种酶的调节之间的关系将通过X射线晶体学的结构表征进一步细化。同时，我们将使用遗传学，分子生物学和植物感染实验来确定cdG结合COR生物合成的生理相关性，以及其对植物中的P.erythingae毒力的影响。

Pseudomonas syringae is a widespread plant pathogen responsible for yield losses in crops worldwide. The phytotoxin coronatine (COR) is produced by several P. syringae pathovars and plays an important role in initiating plant infections. COR suppresses plant immunity, inhibits the closure of stomata, and induces chlorosis (yellowing) of infected tissues. We recently showed that the widespread bacterial signalling molecule cyclic-di-GMP (cdG) binds to three enzymes of the COR biosynthesis pathway. This finding implicates cdG in COR regulation and in the control of P. syringae plant infection. In this project, we will use a combination of genetics, biochemistry and structural biology to define how cdG-binding controls COR biosynthesis in P. syringae. The project will first conduct an indepth biochemical analysis of cdG-binding to the COR-biosynthetic enzymes. The relationship between cdG and regulation of each enzyme will be further refined through structural characterization by X-ray crystallography. In parallel, we will use genetics, molecular biology and plant infection experiments to determine the physiological relevance of cdG-binding to COR biosynthesis, and its impact on P. syringae virulence in planta.