PARACOCCUS DENITRIFICANS IRON TRANSPORT APPARATUS

该计划将侧重于铁的生物有机化学 由Paracoccus acetificans进行的帕拉菌素加工，即，的 微生物的铁吸收装置。 将特别强调 对羟基苯甲酸铁受体的作用。 我们的研究 迄今已揭示，1）对羟基苯甲酸铁的动力学 促进铁吸收与“出租车”机制一致 其中对羟基苯甲酸铁被吸附到 微生物、释放的铁和去铁配体 2）微生物具有80 kD的外膜 一种可通过铁饥饿诱导的蛋白质，与铁-L-羟苯肌动蛋白结合 具有0.7uM的表观Kd， 基本上纯化的; 3）该蛋白质不从 对羟基苯甲酸铁自身;和4）光亲和标记， L-对羟基苯甲酸肌动蛋白叠氮化物可用于标记对羟基苯甲酸铁 受体蛋白 有了这些发现和我们现有的技术 我们将回答以下问题，问题 虽然不是唯一的，但主要集中在 parabactin受体。1)基质特异性如何 对羟基苯甲酸铁受体？ 2)是去铁化羟巴肌动蛋白 作为完整的帕拉肌动蛋白释放？ 3)铁是如何从 在它与受体结合后，对羟基苯甲酸铁？ 四、 受体蛋白的哪些结构特征对 对羟基苯甲酸铁处理，即，关键结构是什么 负责结合的蛋白质的组成部分？ parabactin铁受体蛋白的相关性部分是 与最近对利用这些表面的兴趣有关 表达的蛋白质在疫苗的发展， 机会性细菌 不幸的是， 这些铁载体受体的分离和性质， 这一计划至少可以部分缓解这一问题。

This program will focus on the bioorganic chemistry of ferric parabactin processing by Paracoccus denitrificans, i.e., the microorganism's iron uptake apparatus. Special emphasis will be placed on the role of the ferric parabactin receptor. Our studies to date have revealed that 1) the kinetics of ferric parabactin promoted iron uptake are consistent with a "Taxi Cab" mechanism in which ferric parabactin is adsorbed to the surface of the microorganism, the iron liberated and the deferrated ligand released; 2) the microorganism has an 80kD outer membrane protein inducible by iron starvation that binds ferric L-parabactin with an apparent Kd of 0.7uM, a protein which we have substantially purified; 3) this protein does not release iron from ferric parabactin by itself; and 4) the photoaffinity label, ferric L-parabactin azide can be utilized to label the ferric parabactin receptor protein. With these findings in hand and with the techniques we have developed, we will address the following questions, questions which although not exclusively, are largely focused on the role on the ferric parabactin receptor. 1) How substrate specific is the ferric parabactin receptor? 2) Is deferrated ferric parabactin released as intact parabactin? 3) How is iron liberated from ferric parabactin after it has been bound to the receptor? 4) What structural features of the receptor protein are critical to ferric parabactin processing, i.e., what are the key structural components of the protein responsible for binding? The relevance of the ferric parabactin receptor protein is in part associated with the a recent interest in utilizing these surface expressed proteins in the development of vaccines for opportunistic bacteria. Unfortunately, little is known about the isolation and properties of these siderophore receptors, a situation which this program will alleviate at least in part.