Fungal Pheromone Receptors in Host-Pathogen Interactions

G蛋白偶联受体(GPCRs)形成了一个超家族的细胞表面受体，在真核生物分类群中被发现，例如，仅在人类中就有&GT；800独特的GPCRs。真菌的Ste2p和Ste3p GPCRs介导交配反应，信息素刺激受体导致信号转导事件、细胞周期停滞和细胞融合。然而，最近的一些发现表明，这些信息素受体的相关性和相关机制可能比这更广泛。一方面，最近的一份报告表明，Ste2p参与了过氧化物酶介导的病原真菌对宿主的化学吸引。另一方面，是偏向信号的发现，其中单个GPCR可以被多个不同的配体刺激，每个配体刺激不同的G亚基和阻滞素。我们自己最近的工作已经发现了酵母Ste2p在经典细胞周期停滞与下游细胞壁降解/突起形成之间存在偏差功能的可能性，以及拦截素在介导这些反应中的可能作用。*这些发现共同提出了这样的假设，即宿主-病原体化学吸引的Ste2p相关机制在病原真菌中是保守的，刺激反应的配体的性质是过氧化物酶修饰的细胞壁成分选择性地刺激与arrestin相关的有偏见的信号通路。我们将通过真菌遗传实验、半靶向代谢组学以及长期而言结合定点突变、功能分析和结构研究的经典重组分析来验证这一假说。这项研究计划将使3个硕士和2个博士研究生在遗传学，细胞生物学和生物化学(包括。代谢组学和计算/结构生物学)。*真菌感染是一个广谱问题，影响人和牲畜的健康以及大多数农作物的产量。这项提案的目标是禾谷镰刀菌，它是谷类作物中镰刀菌赤霉病(FHB)的病原体，其中包括有害真菌毒素的沉积。FHB仅在加拿大每年就造成数亿美元的经济损失，并在更广泛的范围内威胁世界粮食供应。常用的抗真菌药物一般都是通过靶向真菌细胞膜的可塑性来发挥作用的。然而，抗药性正在发展，目前缺乏特异性影响了环境中的其他生物。当务之急是开发新的、更具体的、具有替代作用模式的抗真菌药物。要做到这一点，我们必须对真菌感染的基础有一个完整的了解。

G-protein Coupled Receptors (GPCRs) form a superfamily of cell surface receptors that are found across eukaryotic taxa, with, for example >800 unique GPCRs in humans alone. The fungal Ste2p and Ste3p GPCRs mediate mating responses, with stimulation of the receptors by pheromones leading to well-documented signal transduction events, cell-cycle arrest and cellular fusion. However a number of recent findings suggest the relevance and associated mechanisms of these pheromone receptors may be much broader than this. On the one hand, a recent report has implicated Ste2p in the peroxidase-mediated chemo-attraction of pathogenic fungi to hosts. On the other hand, is the discovery of biased-signalling' where individual GPCRs can be stimulated by multiple different ligands, each stimulating different G subunits and arrestins. Our own recent work has yielded evidence highlighting the possibility of biased' functionalities for yeast Ste2p in classical cell cycle arrest versus downstream cell wall degradation/projection formation, and a possible role for arrestins in mediating these latter responses.****Together these findings raise the hypothesis that the Ste2p associated mechanism of host-pathogen chemo-attraction is conserved across pathogenic fungi, and that the nature of the ligand stimulating the response is a peroxidase-modified cell wall component selectively stimulating an arrestin-associated biased-signaling pathway. We will test this hypothesis through a combination of fungal genetic experiments, semi-targeted metabolomics, and in the longer-term, classical recombinant analyses combining site directed mutagenesis with functional assays and structural investigations. This program of research will enable the training of 3 MSc and 2 PhD graduate students in the fields of genetics, cell biology and biochemistry (incl. metabolomics and computational/structural biology).****Fungal infection is a broad-spectrum problem, affecting the health of humans and livestock as well as the productivity of most agricultural crops. Targeted in this proposal is Fusarium graminearum, the causative agent of Fusarium Head Blight (FHB) in cereal crops, which includes deposition of hazardous mycotoxins. FHB causes $ 100's of millions in economic losses annually in Canada alone, and threatens world food supplies more broadly. Commonly used antifungals generally all work by targeting the plasticity of the fungal cell membrane. However resistance is developing, and the current lack of specificity impacts other organisms in the environment. It is imperative that new more specific antifungals, with alternate modes of action, are developed. To enable this, it is essential that we have a complete understanding of the basis of fungal infection.*********