Hemoglobin I From Lucina Pectinata: A Model for Hydrogen Sulfide Reactivity Within Hemeproteins

热带栉孔扇贝生活在硫化物丰富的环境中，其特点是存在共生的硫化物氧化细菌，需要提供硫化氢和氧气。负责将硫化氢输送到细菌的生物分子是一种名为血红蛋白I(HBI)的血红素蛋白。HBI是生物体中为数不多的已知的硫化氢载体之一，它在生理上与铁血红素铁中心的这一分子结合，以维持与细菌的共生关系，并保护文蛤免受硫化氢毒害。生理上相关的硫化氢配体与HBI和其他血红素蛋白的结合、稳定和解离机制还没有建立起来。在这个项目中，将研究HBI-硫化氢复合体的结构和反应活性之间的关系，以确定血红素口袋中氨基酸的化学性质如何影响血红素蛋白质中的硫化氢结合和氢键相互作用。将结合分子生物学和生物物理技术进行研究。此外，还将检查HBI-H_2S部分的HBI-H_2S核磁共振化学位移和EXAFS距离的相关性。该项目的智力优势在于确定了硫化氢和HBI的结构、动力学和反应性，并了解了血红蛋白向共生菌释放硫化氢的机制。了解HBI传输硫化氢的生物物理基础有助于未来开发生物传感器来检测生态和生物环境中的硫化氢；硫化氢是一种已知的有毒化合物。广泛的影响：这个跨学科的项目将被用作指导研究生和本科生的教学工具，并增加他们向社会表达研究成果的知识和沟通能力。因此，对社会的更广泛影响是增加受过良好训练的学生的数量所固有的，这些学生能够充分实现他们的学术或工业生涯。该项目还将通过GK-12计划加强对大学预科学生和教师的接触。

The tropical clam Lucina pectinata lives in sulfide-rich environments and is characterized by the presence of symbiotic sulfide-oxidizing bacteria that need to be supplied with both H2S and O2. The biological molecule responsible for delivering H2S to the bacteria is a heme protein called hemoglobin I (HbI). HbI is one of the few known H2S carriers in organisms that have been implicated in physiologically binding this molecule in the ferric heme iron center so as to maintain the symbiotic relationship with the bacteria as well as to protect the clam from H2S toxicity. A thorough understanding of the association, stabilization, and dissociation mechanism of the physiological relevant H2S ligand with HbI and other heme proteins has not been established yet. In this project, the relationship between structure and reactivity of the HbI-H2S complex will be investigated to define how the chemical nature of the amino acids in the heme pocket affects H2S binding and hydrogen bonding interactions in heme proteins. A combination of molecular biology and biophysical techniques will be used. In addition, correlations of HbI-H2S NMR chemical shifts and EXAFS distances of the HbI-H2S moiety will be examined. The intellectual merits of the project are to determine the structure, dynamics, and reactivity of H2S and HbI and to understand the mechanism of H2S release by the hemoglobin to the symbiotic bacteria. Understanding the biophysical basis H2S transport by HbI could help in the future developments of a biosensor to detect H2S in ecological and biological environments; H2S is a known toxic compound.Broader Impacts: This interdisciplinary project will be used as teaching tools to mentor graduate and undergraduate students and to increase their knowledge and communication abilities to express research results to society. Consequently, the broader impacts to society are inherent to increasing the number of well-trained students capable of fully achieving their academic or industrial career. The project will also enhance outreach to pre-college students and teachers through the GK-12 program.