Elucidation of the Role of the Heme Regulatory Motif in Heme Oxygenase-2

阐明血红素调节基序在 Heme Oxygenase-2 中的作用

基本信息

批准号：
7583965
负责人：
Stephen Wiley Ragsdale
金额：
$ 18.21万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-04-01 至 2010-03-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Heme oxygenase catalyzes the conversion of heme to biliverdin, CO, and iron. The two forms of heme oxygenase (heme oxygenase-1 and heme oxygenase-2) share similar physical and kinetic properties but exhibit different physiological roles and organ locations. The linkage between heme oxygenase-2 and a Caactivated high conductance potassium channel (the BK or Slopoke channel) has been strongly implicated in the control of ventilation by the carotid body in response to changes in the blood oxygen concentration. The major apparent distinction between the sequences of heme oxygenase-1 and heme oxygenase-2 is the occurrence of heme responsive (or regulatory) motifs (HRMs) in heme oxygenase-2. The interaction of heme with HRMs has been proposed to control the activity or stability of several regulatory proteins. Based on recent results, HRM does not bind heme per se or affect HO-2 stability, but appears to act as a redox switch involved in regulating the affinity of heme oxygenase-2 for heme and the spin state of the ferric heme. We plan to use spectroscopic, kinetic, molecular genetic, and electrophysiology studies to determine the role of the HRM in controlling heme oxygenase-2 structure and function. We will characterize the heme and HRM thiol/disulfide redox centers in heme oxygenase-2 by spectroscopic and kinetic methods and determine the redox state of the HRM in vitro and in vivo under various physiological conditions. We also will perform spectroscopic and electrophysiology measurements to determine the mechanism by which heme oxygenase-2 influences BK channel function. PUBLIC HEALTH RELEVANCE Heme oxygenase is the only mammalian protein known to degrade heme and sits at the nexus of several major redox and metal regulatory systems. Two Heme Regulatory Motifs at the C- terminal end of heme oxygenase-2 (HO-2) differentiate it from heme oxygenase-1. This proposal is aimed at determining how(s) these Heme Regulatory Motifs regulate the enzymatic and regulatory properties of HO-2.

描述（由申请人提供）：血红素加氧酶催化血红素向Biliverdin，CO和铁的转化。血红素氧酶的两种形式（血红素加氧酶-1和血红素氧酶-2）具有相似的物理和动力学特性，但具有不同的生理作用和器官位置。血红素加氧酶-2与驱虫高电导钾通道（BK或Slopoke通道）之间的连接密切与颈动脉体进行通风的控制，以响应血氧浓度的变化。血红素加氧酶-1和血红素氧酶-2的序列之间的主要明显区别是血红素反应型（或调节）基序（HRMS）在血红素氧酶-2中的发生。已经提出了血红素与HRMS的相互作用来控制几种调节蛋白的活性或稳定性。根据最近的结果，HRM不结合血红素本身或影响HO-2稳定性，但似乎充当氧化还原开关，涉及调节血红素氧酶-2对血红素的亲和力和铁血红素铁的旋转状态。我们计划使用光谱，动力学，分子遗传学和电生理研究来确定HRM在控制血红素氧酶-2结构和功能中的作用。我们将通过光谱和动力学方法表征血红素氧酶-2中的血红素和HRM硫醇/二硫化物氧化还原中心，并在各种生理条件下确定体外和体内HRM的氧化还原状态。我们还将执行光谱和电生理测量值，以确定血红素氧酶-2影响BK通道功能的机制。公共卫生相关性血红素氧酶是唯一已知降解血红素并坐落在几种主要氧化还原和金属调节系统的Nexus的哺乳动物蛋白。血红素氧酶-2（HO-2）的C-末端的两个血红素调节基序将其与血红素加氧酶-1区分开。该建议旨在确定这些血红素调节基序如何调节HO-2的酶促和调节性能。