CooA: A Hemoprotein CO Sensor

CooA：血红素蛋白 CO 传感器

• 批准号: 6624289
• 负责人: Judith N Burstyn
• 金额: $ 18.19万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2006-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6624289
• 关键词: DNA binding protein; Raman spectrometry; Rhodospirillum; X ray crystallography; bacterial proteins; biosensor device; carbon monoxide; circular magnetic dichroism; cofactor; conformation; cyclic AMP; cyclic AMP receptors; fluorescence spectrometry; heme; hemoprotein; metalloporphyrins; nuclear magnetic resonance spectroscopy; oxidation reduction reaction; proline; protein structure function; stop flow technique; thermodynamics

The long-term goal of this project is to understand how CO functions as a cellular signal. There is considerable evidence supporting a role for CO as a regulator in human vascular and neural tissue, but the mechanism of action of CO is as yet incompletely understood. This project is to investigate the only known CO sensor, the hemoprotein CooA from the photosynthetic bacterium Rhodospirillum rubrum, in order to elucidate the mechanism by which this protein senses CO. The presumed receptor for CO in mammalian tissue, soluble guanylyl cyclase, is also a hemoprotein and a number of other hemoproteins are now known to serve as gas sensors. Understanding the function of the CO sensor CooA will provide a foundation for understanding hemoprotein sensors in human physiology. CooA is a member of the CRP (cAMP receptor protein) family of transcription regulators. In the presence of CO, CooA binds to DNA and turns on the expression of a multicomponent CO-oxidation system in R. rubrum. The cooperative binding of oxygen to hemoglobin is the paradigm for understanding how heme can function as a regulator of protein function. Like hemoglobin, CooA is proposed to undergo a conformational change that is triggered by the binding of CO to the heme cofactor. The overall objective of the studies outlined in this proposal is to correlate changes in the heme coordination state of CooA with changes in protein conformation in order to understand how the heme serves to regulate protein function. It is our hypothesis that changes in the coordination environment of the heme upon CO binding alter the conformation of CooA, enabling the protein to bind to DNA. There are three Specific Aims that we propose to address in this project period: 1) we will identify the unique coordination characteristics of the N- terminal proline ligand, 2) we will correlate CO binding and oxidation state with changes in protein conformation, and 3) we will identify the changes in heme coordination that induce DNA binding activity. Control of protein conformation through changes in metal coordination geometry is a general mechanism for gas sensing, and it is likely that many proteins that employ this mechanism remain to be discovered. Understanding the mechanism by which CooA senses CO will add to our knowledge of how heme is used as a gas sensor in biology and suggest mechanisms by which CO functions as a signal in human tissues.

该项目的长期目标是了解 CO 如何作为细胞信号发挥作用。 有大量证据支持 CO 在人体血管和神经组织中发挥调节作用，但 CO 的作用机制尚未完全了解。 该项目旨在研究唯一已知的 CO 传感器，即来自光合细菌红色红螺菌的血红素 CooA，以阐明该蛋白感知 CO 的机制。哺乳动物组织中假定的 CO 受体可溶性鸟苷酸环化酶也是一种现在已知血红素蛋白和许多其他血红素蛋白可用作气体传感器。 了解 CO 传感器 CooA 的功能将为了解人体生理学中的血红素传感器奠定基础。 CooA 是转录调节因子 CRP（cAMP 受体蛋白）家族的成员。 在 CO 存在的情况下，CooA 与 DNA 结合并开启 R. rubrum 中多组分 CO 氧化系统的表达。 氧与血红蛋白的协同结合是理解血红素如何充当蛋白质功能调节剂的范例。 与血红蛋白一样，CooA 被认为会经历由 CO 与血红素辅因子结合引发的构象变化。 该提案中概述的研究的总体目标是将 CooA 血红素配位状态的变化与蛋白质构象的变化关联起来，以了解血红素如何调节蛋白质功能。我们的假设是，CO 结合时血红素配位环境的变化会改变 CooA 的构象，从而使蛋白质能够与 DNA 结合。 我们建议在此项目期间解决三个具体目标：1）我们将确定 N 端脯氨酸配体的独特协调特征，2）我们将 CO 结合和氧化态与蛋白质构象的变化相关联，3 ）我们将确定诱导 DNA 结合活性的血红素协调变化。 通过改变金属配位几何形状来控制蛋白质构象是气体传感的一般机制，并且很可能许多采用这种机制的蛋白质仍有待发现。 了解 CooA 感知 CO 的机制将增加我们对血红素如何用作生物学中的气体传感器的了解，并提出 CO 在人体组织中充当信号的机制。