Characterization of lipid signaling altered by T3S effector AvrBsT

描述（由申请人提供）：植物和动物的细菌病原体使用III型分泌（T3S）系统和效应蛋白底物改变真核生理，以促进细菌增殖和宿主定植。植物致病菌中大量的T3S效应物（约20-30种蛋白）预示着植物信号级联中的多个节点正在被靶向。然而，植物靶点的身份和这些T3S效应蛋白操纵植物生理的生化机制尚不清楚。广泛的表型研究支持许多T3S效应物抑制植物免疫系统定植组织的概念。这阐明了基础防御反应和抗性(R)蛋白介导的先天免疫反应在控制植物界细菌感染结果中的重要性。了解植物免疫是如何调节的以及细菌病原体如何操纵其宿主是预防和消除植物疾病所需的基础知识。该项目的长期目标是阐明植物如何整合脂质信号来应对细菌感染。两种保守的真核蛋白- SOBER1（一种脂肪酶）和CIP（一种假定的载脂蛋白）已被鉴定并证明是植物先天免疫反应的重要调节因子。将利用拟南芥的病理系统进行全面的遗传和生化研究，以表征SOBER1和CIP底物的特异性，并确定这些蛋白在细菌感染过程中控制磷脂代谢和信号传导的机制。研究还将旨在确定病原体T3S效应物AvrBsT扰乱受感染植物细胞内脂质稳态的生化机制。这项工作有望为植物控制脂质代谢和信号传导以应对病原体攻击的生化机制提供基础见解。越来越多的证据表明，植物和动物的脂质代谢与免疫之间存在相互作用，这表明，对脂质信号如何启动和终止的基本知识对于充分理解真核生物中免疫系统是如何调节的至关重要。

DESCRIPTION (provided by applicant): Bacterial pathogens of plant and animals use the type III secretion (T3S) system and effector protein substrates to alter eukaryotic physiology to promote bacterial multiplication and host colonization. The large repertoire of T3S effectors (~20-30 proteins) in plant pathogenic bacteria predicts that multiple nodes in plant signaling cascades are being targeted. The identity of the plant targets and the biochemical mechanisms by which these T3S effector proteins manipulate plant physiology however are poorly understood. Extensive phenotypic studies support the concept that many of the T3S effectors suppress the plant immune system to colonize tissues. This illuminates the importance of basal defense responses and resistance (R) protein-mediated innate immune responses in controlling the outcome of bacterial infections in the plant kingdom. Understanding how plant immunity is regulated and how bacterial pathogens manipulate their hosts is fundamental knowledge required for the prevention and elimination of plant disease. The long-term goal of this project is elucidate how plants integrate lipid signals to respond to bacterial infection. Two conserved eukaryotic proteins - SOBER1, a lipase and CIP, a putative apolipoprotein - have been identified and shown to be important regulators of innate immune responses in plants. Comprehensive genetic and biochemical studies will be performed using the Arabidopsis pathosystem to characterize SOBER1 and CIP substrate specificity and to determine the mechanisms by which these proteins control phospholipid metabolism and signaling during bacterial infection. Studies will also be aimed to determine the biochemical mechanisms by which the pathogen T3S effector AvrBsT perturbs lipid homeostasis within infected plant cells. This work is expected to provide fundamental insight to the biochemical mechanisms used by plants to control lipid metabolism and signaling in response to pathogen attack. The growing body of evidence suggesting an interplay between lipid metabolism and immunity in both plants and animals indicates that fundamental knowledge about how lipid signals are initiated and terminated will be essential to fully understand how the immune system is regulated in eukaryotes. PUBLIC HEALTH RELEVANCE: Understanding how plant immunity is regulated and how bacterial pathogens manipulate their hosts is fundamental knowledge required for the prevention and elimination of plant disease.