Deciphering iron/heme homeostasis using the fission yeast model.

使用裂殖酵母模型解读铁/血红素稳态。

• 批准号: RGPIN-2020-04802
• 负责人: Labbé, Simon
• 金额: $ 4.23万
• 依托单位: Université de Sherbrooke
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=717414
• 关键词: Deciphering; iron; heme; homeostasis; using

The long-term goal of this proposal is to decipher the molecular basis of heme acquisition in eukaryotes. Due to its essential physiological role as a cofactor for several key cellular enzymes, organisms have evolved with two different ways to obtain heme: heme biosynthesis and heme uptake from external sources. As opposed to the well-characterized enzymes responsible for heme biosynthesis, knowledge of the players and mechanisms involved in acquisition of exogenous heme is very limited and remains poorly understood. Studies in the Labbe's group are aimed at filling this gap in our knowledge. Our studies use the model organism S. pombe. This yeast, unlike S. cerevisiae, can assimilate exogenous heme, allowing the use of the power of genetics to selectively block heme biosynthesis, setting conditions to investigate the mechanisms by which external heme is taken up by the cells. Our studies have revealed the existence of genes encoding proteins that have novel functions in heme assimilation, yet little is known about them, including their mechanism of action and how they are regulated in response to changes in heme levels. During the next 5 years, we will focus our research program on the following specific aims. 1. Elucidate the molecular basis whereby Shu1, a cell surface-anchored heme receptor, cooperates with its interacting partners in heme transport. Shu1 undergoes heme-stimulated internalization that involves an interaction with Nbr1, which functions as a cargo for ESCRT proteins. We will: a) investigate the heteromeric nature of the Shu1-Nbr1 complex; b) identify a tethering factor(s) that fosters Shu1-Nbr1 association. 2. Elucidate the molecular participation of the heme transporter Str3 and the chaperone Tpx1 in the acquisition and trafficking of heme. Under microaerophilic conditions, disruption of Tpx1 results in cells being unable to use exogenous hemin. We will: a) characterize the heme-binding properties of Tpx1; b) investigate the mechanism whereby Tpx1 and Str3 interact with one another. 3. Determine the pathway whereby heme is required for inhibition of Fep1 under low Fe conditions. Frp1 is a hemeprotein. The repressor Fep1 is constitutively bound to the Frp1 promoter in the absence of heme. In contrast, when exogenous hemin is added, Fep1 dissociates from this promoter, resulting in Frp1 expression. We will: a) identify proteins that are required to signal the presence of heme to Fep1; b) use RNA- ">Students without distinction as to minorities will develop critical skills, allowing them to gain the status of highly trained scientists for the Canadian biotech sector &/or academic research community.

该提案的长期目标是破译真核生物中血红素获取的分子基础。由于其作为几种关键细胞酶的辅助因子的重要生理作用，生物体已经进化出两种不同的方式来获取血红素：血红素生物合成和从外部来源摄取血红素。与负责血红素生物合成的已充分表征的酶相反，对参与外源血红素获取的参与者和机制的了解非常有限，并且仍然知之甚少。拉贝小组的研究旨在填补我们的这一知识空白。 我们的研究使用模式生物粟酒裂殖酵母。与酿酒酵母不同，这种酵母可以同化外源血红素，从而利用遗传学的力量选择性地阻断血红素生物合成，为研究细胞吸收外源血红素的机制创造条件。我们的研究揭示了编码在血红素同化中具有新功能的蛋白质的基因的存在，但人们对它们知之甚少，包括它们的作用机制以及它们如何响应血红素水平的变化而受到调节。 未来5年，我们的研究计划将重点关注以下具体目标。 1. 阐明细胞表面锚定血红素受体 Shu1 与其相互作用伙伴在血红素运输中合作的分子基础。 Shu1 经历血红素刺激的内化，涉及与 Nbr1 的相互作用，Nbr1 充当 ESCRT 蛋白的货物。我们将： a) 研究 Shu1-Nbr1 复合物的异聚性质； b) 确定促进 Shu1-Nbr1 关联的束缚因子。 2. 阐明血红素转运蛋白 Str3 和伴侣 Tpx1 在血红素获取和运输中的分子参与。在微需氧条件下，Tpx1 的破坏导致细胞无法使用外源血红素。我们将： a) 表征 Tpx1 的血红素结合特性； b) 研究 Tpx1 和 Str3 相互作用的机制。 3.确定在低Fe条件下抑制Fep1所需血红素的途径。 Frp1 是一种血红素蛋白。在没有血红素的情况下，阻遏蛋白 Fep1 与 Frp1 启动子组成型结合。相反，当添加外源血红​​素时，Fep1 与该启动子解离，导致 Frp1 表达。我们将： a) 鉴定向 Fep1 发出血红素存在信号所需的蛋白质； b) 使用RNA->学生无论少数群体都将发展关键技能，使他们能够获得加拿大生物技术部门和/或学术研究界训练有素的科学家的地位。