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 微生物产生的次生代谢产物以获得 Fe(III) 来自有氧环境。 三价铁铁载体复合物是 通过高亲和力和特异性摄取系统转运至细胞内 它使用几种膜蛋白。 在革兰氏阴性细菌中 外膜受体蛋白赋予该过程特异性。 大肠杆菌 具有铁载体的外膜 (OM) 受体蛋白 (FepA) 它产生（肠杆菌素），但它也有 OM 受体蛋白 它不产生 Fe(III) 铁载体复合物；例如，FhuA 对于铁铬，FecA 对于柠檬酸铁 (III)。 主要目标为 本申请是确定这些受体的结构 蛋白质及其与同源 Fe(III) 铁载体的复合物 晶体X射线衍射。 已表明溶解的 FepA、 一旦纯化，保留其特异性并且构象紧密 与膜中的类似或相同。 菲普A 蛋白质已结晶并显示出 5.5 A 的衍射（旋转 阳极）和 3.3 A（同步加速器），空间群 P21，使用薄 (50y) 盘子。 获得 3 A 分辨率的结构似乎很实用 具有稍厚的晶体。 结构测定也 计划用于复杂的 FepA.Fe(III) 肠杆菌素。 两种结构都将 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。 结构性 信息也将与动力学和热力学相关 使用该蛋白质进行研究。 相似的单晶结构 计划对 FhuA 及其复合物进行测定和物理研究 含有铁铬、FecA 和 PupA（来自假单胞菌 WCS 358）。 这 项目还提出了新铁载体的结构测定和 Fe(III) 特异性的合成配体。 后者很重要，因为 用于治疗铁超载和可能的其他疾病的口服活性药物 涉及铁的疾病，例如疟疾。