Characteristics of chloroquine translocation by pfCRT

疟疾继续成为发展中国家最大的死亡原因之一。目前，主要的治疗策略是药物管理，或化疗。氯喹是使用最广泛的抗疟疾药物之一。氯喹进入疟原虫时，疟原虫驻留在红细胞中。在此期间，寄生虫通过消化富含蛋白质的红细胞环境而生长。这种消化发生在寄生虫的一个特定的隔间里，被称为食物液泡。氯喹也进入食物液泡并抑制红细胞蛋白消化的特定途径。反过来，这会导致有毒副产品的积累，最终导致寄生虫死亡。不幸的是，在世界上许多地区，疟疾寄生虫已经对氯喹和许多其他抗疟疾药物产生了耐药性。有许多途径有助于疟疾的耐药性，但与氯喹耐药性相关的主要途径是由PfCRT基因突变引起的。PfCRT基因产生一种蛋白质，这种蛋白质驻留在食物液泡表面，被认为是通过改变在这个隔室中积累的氯喹的数量来赋予耐药性。目前还不清楚这种蛋白质在寄生虫体内的正常作用，以及突变对其活性的影响。我们的主要目的是确定PfCRT蛋白如何促进对氯喹的耐药性，以及它的作用是否可以克服。为了使我们能够达到这一目标，我们开发了一种新的实验系统来直接检测PfCRT的分离活性。该系统将使我们能够审查下列关键问题：(i)提供关于PfCRT针对哪些抗疟疾药物（氯喹除外）并因此产生耐药性的信息。能够抑制PfCRT的化合物目录，这些化合物可能恢复氯喹的积累并克服耐药性。正性化合物可以在未来的化学项目中用于开发更有效的药剂。（iii）确定PfCRT是以能量依赖的方式泵送药物，还是仅仅作为氯喹从食物液泡中流出的孔。更好地了解PfCRT如何在疟疾中引起对氯喹的耐药性，将大大加强克服其有害活性的未来战略，从而规避对化疗的耐药性。

Malaria continues its reign as one of the largest causes of death in the developing world. Currently, the main therapeutic strategy is drug administration, or chemotherapy. The drug chloroquine is one of the most widely used anti-malarial agents. Chloroquine enters the malarial parasite whilst it resides in red blood cells (erythrocytes). During this period the parasite grows by virtue of digesting the protein rich erythrocyte environment. This digestion occurs within a specific compartment of the parasite, known as the food vacuole. Chloroquine also enters the food vacuole and inhibits a specific pathway involved in digestion of erythrocyte proteins. In turn, this causes a build up of toxic by-products and ultimately leads to death of the parasite. Unfortunately, in many regions worldwide, the malaria parasites have built up a resistance to chloroquine, and many other anti-malarial drugs. There are numerous pathways contributing to resistance in malaria, but the main one associated with chloroquine resistance is caused by mutations in the PfCRT gene. The PfCRT gene produces a protein that resides on the surface of the food vacuole and is thought to confer resistance by altering the amount of chloroquine accumulating in this compartment. It is unclear what this protein does normally in the parasite and what consequences the mutations have on its activity.Our primary aim is to determine how the PfCRT protein contributes to resistance against chloroquine and whether its actions can be overcome.To enable us to reach this objective, we have developed a novel experimental system to directly examine PfCRT activity in isolation. The system will enable us to examine the following key issues:(i) Providing information on which anti-malarial drugs (other than chloroquine) are targeted by PfCRT and therefore succumb to resistance.(ii) Catalogue compounds capable of inhibiting PfCRT, which could potentially restore chloroquine accumulation and overcome resistance. Positive compounds could be used in future chemical programs to develop more potent agents.(iii) Determine whether PfCRT pumps drugs in an energy dependent manner or by simply acting as a pore through which chloroquine can exit the food vacuole.Providing a greater understanding of how PfCRT causes resistance to chloroquine in malaria will significantly enhance future strategies to overcome its unwanted activity and thereby circumvent the resistance to chemotherapy.