MDR ABC TRANSPORTERS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 我们的项目重点是细菌ABC转运蛋白，它是真核细胞多药耐药(MDR)蛋白(如P-糖蛋白(P-gp))的结构和功能密切的同源物。一系列针对癌细胞的药物可诱导多药耐药ABC转运蛋白的过度表达。多药耐药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转运体将ATP的结合和水解与其所谓的ABC(三磷酸腺苷结合盒)结构域的二聚化和解离偶联。这些事件触发了作为转运机制基础的膜域的构象变化。 到目前为止，我们已经能够收集到4.2A分辨率(X25)的完整ABC转运体的Apo形式的本地数据。我们目前正在寻找重原子的衍生物，以便对这些原始数据进行定相，并解决结构问题。 该项目的另一部分重点是解决这种转运体的ATP结合形式的结构。我们已经能够获得这种形式的晶体。但是，它们的衍射质量还有待提高。 获得这种ABC转运蛋白的Apo和ATP结合形式的结构应该可以让我们观察到触发ABC外排转运蛋白如P-糖蛋白转运的构象变化。

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.