The Bioinorgainic Chemistry and Nickel: The Ureases and NikR

描述（由申请人提供）：我们的长期目标是加强我们对金属蛋白结构，功能和抑制的理解。我们将使用理论化学、计算化学和药物化学的工具。本项目的目标是在分子水平上了解含镍金属蛋白的稳态、调控和结构与功能。特别是，我们建议研究这些酶的催化机制、稳定性和抑制作用，并通过这种理解增强我们对酶催化、极端环境下酶稳定性和小分子治疗学发展的理解。这些酶参与了广泛的疾病状态，对这一酶家族的结构和功能的透彻理解将影响我们改变这些酶行为的能力。镍离子进入细胞的调控是由镍依赖转录因子NikR控制的，NikR抑制大肠杆菌中镍膜转运蛋白nikABCDE的表达。我们建议对NikR的结构、功能和动力学进行详细的了解，以便深入了解细胞中镍离子浓度是如何调节的。主要研究的酶是产气克雷伯氏杆菌、巴氏杆菌和幽门螺杆菌的酶，我们将研究大肠杆菌的转录因子NikR。以脲酶为例，我们要解决的生物学问题是脲酶如何催化尿素转化为氨和氨基甲酸酯的速度至少是未催化反应的10 × 14倍，以及幽门螺杆菌中的脲酶如何使这种细菌能够在肠道的低ph条件下生存。在NikR的案例中，我们要解决的生物学问题是，细胞中的金属离子浓度是如何被调节的，这是有毒性的，但又是必要的。本文将借助量子力学和分子动力学模拟等理论工具，研究尿素的非催化分解和催化分解，幽门螺杆菌脲酶在低pH下的稳定性，以及大肠杆菌NikR的结构、功能和动力学。通过对脲酶催化和抑制的了解以及对细胞内金属离子调节的进一步了解，对这些过程的深入了解将对人类健康产生重大影响。公共卫生相关性：通过对脲酶和金属调节蛋白NikR的研究，我们将增加我们对如何控制幽门螺杆菌形成的人类溃疡的理解，我们将增加我们对细胞中金属离子调节的理解，其功能障碍通过阿尔茨海默病和卢伽雷氏病等疾病对人类健康产生影响。

DESCRIPTION (provided by applicant): Our long-term goal is to enhance our understanding of metalloprotein structure, function and inhibition. The tools we will use are those of theoretical, computational and medicinal chemistry. The goal of this project is to understand, at the molecular-level, nickel homeostatis, regulation and the structure and function of nickel containing metalloproteins. In particular, we propose to study the catalytic mechanism, stability and inhibition of the ureases and through this understanding enhance our comprehension of enzyme catalysis, enzyme stability in extreme environments and the development of small-molecule therapeutics. The ureases are involved in a broad range of diseased states and a thorough understanding of the structure and function of this family of enzymes will impact our ability to modify the behavior of the ureases. The regulation of nickel ion import into a cell is governed by the nickel dependent transcription factor NikR, which represses the expression of the nickel membrane transporter nikABCDE in E. coli. We propose to develop a detailed understanding of the structure, function and dynamics of NikR, in order to gain insights into how nickel ion concentrations are regulated in cells. The primary enzymes that will be studied are the ureases from K. aerogenes, B. pasteurii and H. pylori and we will study the transcription factor NikR from E. coli. In the case of the ureases, the biological questions we are addressing is how do ureases catalyze the conversion of urea to ammonia and carbamate at a rate that is at least 10x14 times greater than the uncatalyzed reaction as well as how does the urease from H. pylori give this bacterium the ability to survive the low-pH conditions of the gut. In the case of NikR the biological question we are addressing is how toxic, yet necessary, metal ion concentrations are regulated in cells. With the aid of theoretical tools like quantum mechanics and molecular dynamics simulations we will study the uncatalyzed and the catalyzed decomposition of urea, the stability of H. pylori urease at low pH's and we will study the structure, function and dynamics of E. coli NikR. The insights obtained into these processes will have a major impact on human health through the understanding of urease catalysis and inhibition and via an enhanced understanding of the regulation of metal ions within cells. PUBLIC HEALTH RELEVANCE: Through the study of the enzyme urease and the metalloregulation protein NikR we will increase our understanding of how to control human ulcers formed by H. Pylori and we will increase our understanding of metal ion regulation in cells, whose dysfunction has an impact on human health through diseases like Alzheimer's and Lou Gehrig's disease.