STRUCTURE/FUNCTION OF SIDEROPHORES AND RECEPTOR PROTEINS

铁载体和受体蛋白的结构/功能

• 批准号: 2173802
• 负责人: DICK VAN DER HELM
• 金额: $ 8.82万
• 依托单位: UNIVERSITY OF OKLAHOMA
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-05-01 至 1997-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2173802
• 关键词: X ray crystallography; active transport; bacterial proteins; calorimetry; chemical kinetics; chemical models; conformation; crystallization; iron metabolism; membrane transport proteins; metal complex; microorganism metabolism; protein purification; protein structure function; receptor; receptor binding; siderophores; thermodynamics

DESCRIPTION: (Adapted from applicant's abstract) Siderophores are secondary metabolites produced by microorganisms to acquire Fe(III) from the aerobic environment. The ferric siderophore complexes are transported into the cells by a high affinity and specific uptake system which uses several membrane proteins. In Gram-negative bacteria the outer membrane receptor proteins give this process specificity. E. coli has an outer membrane (OM) receptor protein (FepA) for the siderophore it produces (enterobactin), but it also has OM receptor proteins for Fe(III) siderophore complexes it does not produce; for instance, FhuA for ferrichrome and FecA for Fe(III) citrate. The main goal for the present application is to determine the structures of these receptor proteins and their complexes with cognate Fe(III) siderophore by single crystal X-ray diffraction. It has been shown that solubilized FepA, once purified, retains its specificity and is in a conformation closely similar to or the same as the one it has in the membrane. The FepA protein has been crystallized and shows diffraction to 5.5 A (rotating anode) and 3.3 A (synchrotron) with space group P21, using thin (50y) plates. It appears practical to obtain the structure at 3 A resolution with slightly thicker crystals. A structure determination is also planned for the complex FepA.Fe(III) enterobactin. Both structures will give significant information about the specificity and mechanism of transport and also about membrane transport in general. The structural information will also be correlated with kinetic and thermodynamic studies using the protein. Similar single crystal structure determinations and physical studies are planned on FhuA and its complex with ferrichrome, FecA, and PupA (from Pseudomonas WCS 358). The project also proposes structure determinations of new siderophores and synthetic ligands specific for Fe(III). The latter are important as orally active agents to treat iron overload, and possibly other diseases which involve iron, such as malaria.

描述：（改编自申请人的摘要）铁载体是 微生物产生的二级代谢产物以获取Fe（III） 来自有氧环境。 铁铁载体复合物是 通过高亲和力和特定吸收系统运输到细胞中 它使用几种膜蛋白。 在革兰氏阴性细菌中 外膜受体蛋白具有此过程特异性。 大肠杆菌 具有用于铁载体的外膜（OM）受体蛋白（FEPA） 它产生（肠乳蛋白），但也具有OM受体蛋白 Fe（iii）铁载体复合物，它不会产生；例如，FHUA 用于Ferrichrome和Feca的Fe（III）柠檬酸盐。 主要目标 目前的应用是确定这些受体的结构 蛋白质及其复合物与单一的同源Fe（III）铁载体 晶体X射线衍射。 已经显示出溶解的FEPA， 一旦纯化，保留其特异性并紧密地处于构象中 与膜中的相似或相同。 FEPA 蛋白质已经结晶，显示为5.5 a（旋转 使用薄（50y） 盘子。 以3分辨率获得结构似乎很实际 晶体略厚。 结构的确定也是 计划用于复杂的FEPA.FE（III）肠霉素。 这两个结构都会 提供有关特异性和机制的重要信息 运输以及一般的膜运输。 结构 信息也将与动力学和热力学相关 使用蛋白质的研究。 类似的单晶结构 计划对FHUA及其复杂的确定和物理研究 与Ferrichrome，Feca和Pupa（来自Pseudomonas WCS 358）。 这 项目还提出了新的铁载体的结构确定和 特定于Fe（III）的合成配体。 后者很重要 口服活性剂以治疗铁超负荷，甚至可能其他疾病 涉及铁，例如疟疾。