The Plasmodial Surface Anion Channel And Malaria Parasite Nutrient Acquisition

疟原虫表面阴离子通道与疟原虫营养获取

基本信息

批准号：
7732557
负责人：
SANJAY A DESAI
金额：
$ 73.01万
依托单位：
NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/7732557
关键词：
Accounting Affinity Agonist Anions Anti-malarial drug resistance Antimalarials Basic Science Biochemical Biological Biological Assay Cells Cellular biology Chemistry Cysteine Cysteine Protease Erythrocytes Genetic Goals Growth Human In Vitro Informatics Ion Channel Ion Transport Leupeptins Lipid Biochemistry Malaria Measures Mediating Membrane Molecular Molecular and Cellular Biology Mutation Nutrient Parasite resistance Parasites Pathway interactions Pharmaceutical Preparations Physiology Program Development Property Proteins Range Resistance Serine Protease Serine Proteinase Inhibitors Specificity Structure Structure-Activity Relationship Surface Therapeutic Transmembrane Transport Up-Regulation Work base drug discovery gene cloning high throughput screening insight leupeptin novel parasite genome patch clamp resistance mechanism small molecule libraries solute uptake

项目摘要

The Apicomplexan Molecular Physiology Section continued its studies of the plasmodial surface anion channel (PSAC) and made two significant contributions. First, we identified and characterized a novel antimalarial drug resistance mechanism based on reduced drug uptake via PSAC (Antimicrob. Agents Chemother. 52:2346, 2008). This discovery entailed in vitro selection of malaria parasites resistant to leupeptin, a broad specificity cysteine and serine protease inhibitor. Because leupeptin has multiple targets within infected cells, workers assumed that resistance would not be acquired easily. We found that leupeptin resistance was not associated with upregulation of cysteine protease activity, reduced leupeptin sensitivity of this activity, or expression level changes for putative cysteine or serine proteases in the parasite genome. Instead, it was associated with marked changes in PSAC, as measured with patch-clamp and other transport assays. PSAC antagonists were found to antagonize parasite growth inhibition by leupeptin, suggesting that leupeptin can access its intracellular targets only after passive uptake via PSAC. The resistant parasite's channel mediated significantly reduced leupeptin uptake and could fully account for the acquired resistance. Reduced passive uptake of bulky hydrophilic antimalarial agents via selection of mutations in PSAC represents a novel antimalarial drug resistance mechanism that should be considered by drug discovery and development programs. Second, we carried out additional high-throughput screens of small molecule libraries for PSAC antagonists. These screens have successfully identified novel antagonists with unique properties. These include compounds that have the highest known affinity (low nanomolar) and specificity for PSAC inhibition, novel agonists that increase transport via PSAC, compounds that alter solute selectivity, and compounds that provide new insights into the structure and function of PSAC.

Apicomplexan分子生理学部分继续研究了质体表面阴离子通道（PSAC），并做出了两个重要的贡献。首先，我们确定并表征了一种基于PSAC的药物摄取减少的新型抗疟疾耐药机制（抗微生物。代理化学剂。52：2346，2008）。这一发现需要在体外选择对亮肽素的疟疾寄生虫，这是一种广泛的特异性半胱氨酸和丝氨酸蛋白酶抑制剂。由于亮肽素在受感染的细胞中具有多个靶标，因此工人认为不容易获得电阻。我们发现，亮肽素耐药性与半胱氨酸蛋白酶活性的上调，该活性的亮肽素敏感性降低或寄生虫基因组中假定半胱氨酸或丝氨酸蛋白酶的表达水平变化。取而代之的是，它与PSAC的明显变化有关，如贴片钳和其他传输分析所测量。发现PSAC拮抗剂可以通过亮肽素拮抗寄生虫的生长抑制作用，这表明亮肽素只有在通过PSAC被动吸收后才能进入其细胞内靶标。抗性寄生虫的通道介导可显着降低亮肽素的摄取，并可以完全解释获得的抗药性。通过在PSAC中选择突变，可以减少笨重的亲水性抗疟药剂的被动摄取，代表了一种新型的抗疟疾耐药机制，应通过药物发现和开发计划来考虑。其次，我们为PSAC拮抗剂进行了其他小分子库的高通量屏幕。这些屏幕已成功地鉴定出具有独特特性的新型拮抗剂。这些包括具有最高已知亲和力（低纳摩尔）的化合物和对PSAC抑制的特异性，通过PSAC增加传输的新型激动剂，改变溶质选择性的化合物以及为PSAC的结构和功能提供新见解的化合物。