STRUCTURAL CHARACTERIZATION OF METAL TRANSPORTING PEPTIDES FROM MAMMALS & MICROO

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。革兰氏阴性细菌对铁的吸收是通过使用铁载体(小分子修饰多肽)来完成的。铁载体从外部环境中清除铁，然后被输送回细菌细胞。与有毒金属络合的铁载体已被证明是一种有效的抗菌策略。我们将使用收集的XAFS数据来关联金属结合属性和结构变化。我们还将使用金属结合位的高分辨率XAFS数据来进一步完善我们的X射线晶体结构数据，这将与这些实验并行解决。一种名为胃泌素17的小肽正在研究人类对铁的摄取，胃泌素17在酸性pH条件下在胃腔中发挥作用。Gastrin17已经被证明结合了两个铁原子，尽管还没有收集到结构数据，但证据表明这些铁以双核铁物种的形式结合在一起。XAFS数据不仅将提供铁结合部位的第一张结构图，还可能提供金属相互结合紧密程度的证据。最近有人推测，与一系列有害的神经疾病有关的普里恩蛋白，可能在哺乳动物的突触中作为铜敏感或铜运输蛋白发挥作用。铜结合与蛋白质疾病状态的形成有关，尽管原子分辨结构数据很稀少。X射线结晶学没有什么用处，因为铜结合区域在溶液和固体中都是高度非结构化的。此外，由于铜(Cu2+)的顺磁性，核磁共振技术无法立即探测金属中心周围的区域。因此，我们正在筛选其他具有良好核磁共振特性的金属离子，使用XAFS技术与Cu2+结合环境进行比较。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Iron uptake in gram negative bacteria is accomplished through the use of siderophores (small modified peptides). Siderophores scavenge iron from the external environment and are then transported back into the bacterial cell. Siderophores complexed to toxic metals have been shown to be an effective antibacterial strategy. We will use the collected XAFS data to relate metal-binding properties, and structural changes. We will also use the high resolution XAFS data of the metal-binding sites to further refine our X-ray crystal structure data, which will be solved in parallel with these experiments. Iron uptake in humans is being investigated by the small peptide, gastrin17, which functions in the gastric lumen at acidic pH. Gastrin17 has been shown to bind two Fe-atoms, and although no structural data has yet been collected, evidence suggests these irons are bound as a dinuclear iron species. XAFS data will not only provide the first structural picture of the iron-binding site, but may also provide evidence of how closely the metals are bound with respect to one another. It has recently been postulated that the prion protein, involved in a range of deleterious neurological diseases, may function as a copper-sensing or copper-transporting protein at the synapse in mammals. Copper-binding has been linked to the formation of the disease state of the protein, although atomic resolution structural data is sparse. X-ray crystallography is of little use as the copper-binding region is highly unstructured in solution, as well as the solid state. Also, due to the paramagnetic nature of copper (Cu2+) NMR techniques are unable to probe the region immediately around the metal centre. We are therefore screening other metal ions with favourable NMR properties, using the XAFS technique to compare with the Cu2+-binding environment.