MDR ABC TRANSPORTERS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 我们的项目集中在细菌ABC转运蛋白，这是一个密切的结构和功能同源的真核多药耐药（MDR）蛋白，如P-糖蛋白（P-gp）。靶向癌细胞的多种药物诱导MDR ABC转运蛋白的过度表达。MDR ABC泵拒绝这些药物，因此降低了癌症治疗的有效性。为了实现转运，ABC转运蛋白将ATP的结合和水解与其所谓的ABC（ATP结合盒）结构域的二聚化和解离偶联。这些事件触发膜结构域的构象变化，这些结构域是转运机制的基础。 到目前为止，我们已经能够收集原始数据，分辨率为4.2 A（X25），用于完整ABC转运蛋白的Apo形式。我们目前正在寻找重原子衍生物，以便对这些原生数据进行分相并解决结构问题。 该项目的另一部分重点是解决这种转运蛋白的ATP结合形式的结构。我们已经能够获得这种形式的晶体。然而，它们的衍射质量需要改进。 获得的结构，这ABC转运蛋白在载脂蛋白和ATP结合的形式，应使我们能够观察到的构象变化触发运输ABC外排转运蛋白，如P-糖蛋白。

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. Our project focusses on a bacterial ABC transporter that is a close structural and functional homologue of eukaryotic multi-drug resistance (MDR) proteins such as P-glycoprotein (P-gp). A broad range of drugs that target cancer cells induce the over-expression of MDR ABC transporters. MDR ABC pumps reject these drugs and therefore reduce the effectiveness of cancer treatments. To achieve transport, ABC transporters couple the binding and hydrolysis of ATP to the dimerization and dissociation of their so-called ABC (ATP binding cassette) domains. These events trigger conformational changes in the membrane domains that are at the basis of the transport mechanism. To date, We have been able to collect native data to 4.2 A resolution (X25) for an Apo form of the complete ABC transporter. We are currently looking for heavy atom derivatives in order to phase these native data and solve the structure. Another part of the project foccusses on solving the structure of an ATP-bound form of this transporter. We have been able to obtain crystals of such a form. However, their diffraction quality need to be improved. Obtaining structures of this ABC transporter in both Apo and ATP-bound forms should allow us to observe the conformational changes triggering transport in ABC efflux transporters such as P-glycoprotein.