NOVEL BIOCHEMICAL ROLES FOR IRON REGULATORY PROTEIN 2

铁调节蛋白 2 的新生化作用

• 批准号: 7007329
• 负责人: Elizabeth Ann Leibold
• 金额: $ 21.9万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7007329
• 关键词: Saccharomyces cerevisiae; binding sites; enzyme activity; ferritin; genetic regulation; hydroxylation; immunoprecipitation; iron metabolism; mass spectrometry; matrix assisted laser desorption ionization; oxygen transport; oxygenases; protein binding; protein protein interaction; protein purification; protein structure function; transcription factor

DESCRIPTION (provided by applicant): Due to its unique chemical properties iron has immense versatility in biology. Although this metal is used for myriad of critical processes, in an aerobic environment this comes at a potentially high cost to cells in the form of oxidative damage to proteins, DNA/RNA, and lipids. Mammals have therefore evolved complex regulatory mechanisms devoted to iron homeostasis, where iron regulatory protein 2 (IRP2) serves a critical function. IRP2 is an RNA-binding protein that regulates mRNAs encoding proteins important in iron storage (ferritin) and iron uptake (transferrin receptor). The coupling of cellular iron with the appropriate regulation of these, and other mRNAs, is achieved through iron and oxygen stimulation of IRP2 ubiquitination/degradation. Defining the molecular mechanisms by which IRP2 senses physiologic changes in iron and oxygen and how this signals for its degradation is essential for a comprehensive understanding of mammalian iron homeostasis. Towards this end, we have recently identified a putative iron-binding motif in IRP2. We hypothesize that this site confers a novel iron- and oxygen-dependent enzymatic activity to IRP2, and that this activity is involved in its degradation through a self-modifying mechanism or in catalyzing modifications on other substrates. The specific aims addressed in this R21 application are: (1) Characterize iron-binding to the putative iron-binding site on IRP2 and examine its potential role in mediating IRP2 degradation or in direct regulation of IRP2 target mRNAs and (2) Examine novel iron-dependent IRP2 enzymatic activity. The goal of this work is to define hitherto unidentified IRP2 biochemical activity and identify pathways in which it participates. This work is presented as an R21 application since it satisfies the aims of the R21 mechanism by representing an exploratory high risk study with potentially high impact.

描述（由申请人提供）： 由于其独特的化学性质，铁在生物学中具有巨大的通用性。虽然这种金属用于无数的关键过程，但在有氧环境中，这对细胞来说可能是一个很高的代价，对蛋白质、DNA/RNA和脂质造成氧化损伤。因此，哺乳动物已经进化出复杂的调节机制，致力于铁稳态，其中铁调节蛋白2（IRP 2）发挥关键作用。IRP 2是一种RNA结合蛋白，其调节编码在铁储存（铁蛋白）和铁摄取（转铁蛋白受体）中重要的蛋白质的mRNA。通过铁和氧刺激IRP 2泛素化/降解，实现细胞铁与这些和其他mRNA的适当调节的偶联。定义IRP 2感知铁和氧的生理变化的分子机制以及这种信号如何降解对于全面了解哺乳动物铁稳态至关重要。为此，我们最近确定了一个假定的铁结合基序IRP 2。 我们推测，该网站赋予一种新的铁和氧依赖性酶活性IRP 2，这种活性是参与其降解，通过自我修饰机制或在催化其他底物上的修改。本R21申请的具体目的是：（1）表征与IRP 2上推定的铁结合位点的铁结合，并检查其在介导IRP 2降解或直接调节IRP 2靶mRNA中的潜在作用，以及（2）检查新的铁依赖性IRP 2酶活性。这项工作的目标是定义迄今未鉴定的IRP 2生物化学活性，并确定其参与的途径。这项工作作为R21应用程序介绍，因为它通过代表具有潜在高影响的探索性高风险研究来满足R21机制的目标。