铁吸收调控蛋白Fur的复合物结构和识别机制研究

Although iron is essential for life, high concentration of iron is toxic for the cell by formation of highly reactive radicals. Most bacteria maintain a remarkably precise control over cytoplasmic iron level through ferric uptake regulator (Fur). As a global regulator, Fur regulates the homeostasis of iron and oxygen. Fur recognizes more than 90 diverse genes in the genome that differ in length or sequence, and the binding ratio differs greatly. In many pathogens, such as V. cholerae and C. jejuni, Fur regulates the expression of toxin or many proteins that can acquire iron directly from host. However, the molecular mechanisms and structural basis of Fur-DNA binding remain poorly understood. Unresolved issues include the mechanisms by which metal ions activate Fur, and explanations for why Fur has such a broad substrate binding ability. Which modes Fur uses to recognize DNA and why it has different binding ratio? . In this project, based on our preliminary results, we will determine several Fur structures complexed with different DNAs, and reveal the function of Fur in the iron-uptake process by means of biochemiscal, in vitro and in vivo experiments, molecular biology and protein crystallogphy studies. Furthermore, we will uncover the possible mechanisms of the metal ion-induced conformational changes, the regulatory mechanisms and the DNA recognition of broad target genes by Fur. All these results will be of great significance to research into metabolism between iron and oxygen, biomineralization, magnetosomes synthesis in magnetotactic bacteria and antipathogenic drugs. The results will also provide a direction for development of new materials and new medicines.

铁是生命过程所必需的元素，但是细胞内铁浓度过高会产生高活性的自由基，从而对细胞产生毒害作用。大部分细菌通过铁吸收调控蛋白(Fur)来精细地调控细胞中的铁浓度。Fur是个全局调控因子，调控细胞铁、氧代谢平衡。目前发现Fur调控90多个基因且识别的DNA序列、长度和比例差异很大。很多致病菌是通过Fur来调控致病因子的表达，并从宿主细胞中摄取铁的。到目前为止，Fur与DNA复合物的结构及其识别众多不同DNA机制还不清楚。Fur如何结合不同比例的DNA?它通过哪些方式识别目标基因？. 在前期工作的基础上，本研究将通过生物化学、体内外实验、分子生物学和结构生物学等技术，研究几种Fur识别不同DNA复合物的结构和生化机理，揭示铁吸收调控中的识别机制。本项目将对研究与铁和氧有关的代谢、生物矿化、磁细菌的磁小体合成、病菌的防治和药物开发具有重要的生物学意义，并为磁细菌品种的改良和应用指明方向。

铁是生命过程所必需的元素，但是细胞内铁浓度过高会对细胞产生毒害作用。大部分细菌通过铁吸收调控蛋白(Fur)来精细地调控细胞中的铁浓度。Fur是个全局调控因子，调控细胞铁、氧代谢平衡。目前发现Fur调控90多个基因且识别的DNA序列、长度和比例差异很大。很多致病菌是通过Fur来调控致病因子的表达，并从宿主细胞中摄取铁的。Fur与DNA复合物的结构及其识别众多不同DNA机制还不清楚。.本项目对Fur识别DNA底物进行筛选和复合物结构的解析与功能研究方面，取得一些富有意义的成果，培养高素质的研究生12人。标有本课题资助、以通信作者发表的SCI论文有6篇。解出了6个不同状态下的Fur及其复合物的晶体结构，Fur通过新的机制来识别DNA碱基特异性和构象两种方式共同定位目的序列，并发现金属离子通过稳定DNA结合结构域来激活Fur，在细菌中保守存在。为研究与铁和氧有关的代谢、磁细菌的磁小体合成、病菌的防治和药物开发具有重要的生物学意义，并为磁细菌品种的改良和应用指明方向。