Structural analysis of the siroheme biosynthetic enzyme CysG, a central player in sulfur metabolism

硫代谢中的核心角色西罗血红素生物合成酶 CysG 的结构分析

基本信息

批准号：
1904612
负责人：
Elizabeth Stroupe
金额：
$ 39万
依托单位：
Florida State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-07-15 至 2024-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1904612&HistoricalAwards=false
关键词：
Structural analysis siroheme biosynthetic enzyme

项目摘要

Heme is the iron-containing molecule that allows hemoglobin to carry oxygen in blood. Heme also plays many other important biochemical functions in cells. With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Elizabeth Stroupe at Florida State University to study a special form of heme (called siroheme). Siroheme helps chemically transform environmental sulfur or nitrogen compounds to biologically usable forms using microbes. This research topic is of particular importance because environmental pollution in the form of toxic sulfur byproducts from commercial pig farms has become problematic due to recent flooding in the southern United States. Dr. Stroupe is studying a key enzyme (CysG) made from two bacteria in order to determine the basic science of siroheme formation. By knowing how siroheme is formed, scientists may improve upon the bio-remediation of toxic sulfur compounds. The project trains diverse groups of undergraduate and graduate students in molecular structure determinations and follows the biochemical activity of enzymes at various stages of reaction. Dr. Stroupe and her students impart an appreciation for the role that organic chemistry plays in biology to middle and high school students through the SCIGirls and Florida's Next Generation Science Standards outreach programs.Proteobacteria use a single gene product (CysG) to synthesize siroheme. CsyG is the product of a gene fusion event between a methyltransferase (CysG-A) and a bifunctional dehydrogenase/ferrochelatase (CysG-B). The mechanisms for CysG-B's bifunctionality and its alternative function as a cobaltchelatase are unknown. Other organisms use three distinct enzymes for siroheme synthesis, including the CysG-B homolog SirC, which is a monofunctional dehydrogenase. X-ray crystallography, biochemical analysis, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) are applied to dissect the underlying mechanisms for the last two steps of siroheme synthesis. The questions addressed by this project include how bifunctional active sites in CysG-B catalyze dehydrogenation and metal chelation and how chelatase discriminates between iron and cobalt to make siroheme. Researchers also ask how CysG-B functions as a bifunctional dehydogenase/ferrochelatase when SirC, a homologous enzyme, only functions as a dehydrogenase.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

血红素是含铁的分子，可允许血红蛋白在血液中携带氧气。血红素还扮演细胞中许多其他重要的生化功能。有了这个奖项，化学生命过程的化学过程计划正在为佛罗里达州立大学的伊丽莎白·斯特鲁普（Elizabeth Stroupe）博士提供资金，以研究血红素的特殊形式（称为Siroheme）。 Siroheme有助于使用微生物将化学化学的环境硫或氮化合物转化为生物使用的形式。该研究主题尤其重要，因为由于美国南部最近的洪水，商业养猪场有毒硫副产品形式的环境污染已成为问题。 Stroupe博士正在研究由两种细菌制成的关键酶（CYSG），以确定Siroheme形成的基础科学。通过了解Siroheme的形成方式，科学家可以对有毒硫化合物的生物修复进行改进。该项目培训各种本科生和研究生的分子结构确定群体，并遵循各种反应阶段的酶的生化活性。 Stroupe博士和她的学生通过Scigirls和Florida的下一代科学标准外展计划对有机化学在生物学中的作用表示赞赏。Proteobacteria使用单个基因产品（CYSG）合成Siroheme。 CSYG是甲基转移酶（CYSG-A）和双功能脱氢酶/铁胆酸酯（CYSG-B）之间的基因融合事件的产物。 CYSG-B双方函数的机制及其作为钴切elatase的替代功能尚不清楚。其他生物体使用三种不同的酶进行siroheme合成，包括Cysg-B同源物SIRC，该酶是单官能脱氢酶。 X射线晶体学，生化分析和傅立叶转化离子回旋共振质谱法（FT-ICR MS）用于剖析Siroheme合成的最后两个步骤的基本机制。该项目解决的问题包括Cysg-B中的双功能活性位点如何催化脱氢和金属螯合，以及螯合酶如何区分铁和钴以使Siroheme构成Siroheme。研究人员还询问CYSG-B在同源酶SIRC时如何充当双功能脱氢酶/铁胆酸酯酶，仅作为脱氢酶起作用。该奖项反映了NSF的法定任务，并被认为是通过该基金会的知识分子功能和广泛影响来评估CRITERIA CRITERIA的评估。