AIDS Opportunistic Pathogens: Targeting the Methyl Citrate Cycle

艾滋病机会病原体：针对柠檬酸甲酯循环

• 批准号: 7911623
• 负责人: Brendan Cormack
• 金额: $ 20.5万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-11 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7911623
• 关键词: Accounting; Acetyl Coenzyme A; Acquired Immunodeficiency Syndrome; Affect; Animals; Antifungal Agents; Area; Biochemical; Biological Assay; Branched-Chain Amino Acids; Candida; Candida albicans; Candida glabrata; Carbon; Cell Wall; Cells; Citrates; Clinical; Collection; Data; Development; Disseminated candidiasis; Drug Metabolic Detoxication; Environment; Enzymes; Exposure to; Fatty Acids; Future; Genes; Genetic; HIV; HIV Seropositivity; Human; Human Development; In Vitro; Individual; Infection; Investigation; Lead; Ligase; Membrane; Metabolic; Metabolism; Modeling; Mycoses; Nitrogen; Pathway interactions; Patients; Phagocytosis; Pharmaceutical Preparations; Population; Propionates; Proteins; Pyruvate; Pyruvates; Reaction; Recombinants; Resistance; Role; Screening procedure; Series; Source; Testing; Therapeutic; Therapeutic Intervention; Toxic effect; Toxin; Triazoles; United States; United States National Institutes of Health; Virulence; Yeasts; base; design; high risk; inhibitor/antagonist; interest; macrophage; metabolic poison; mutant; novel; oxidation; pathogen; propionyl-coenzyme A; protein degradation; public health relevance; small molecule; therapeutic target; treatment strategy

DESCRIPTION (provided by applicant): Candida glabrata is an important opportunistic pathogen in HIV seropositive and HIV seronegative populations. In the United States, most clinical series over the last 15 years show that C. glabrata accounts for 15-20% of mucosal and disseminated candidiasis, C. glabrata is innately resistant to triazole antifungals, and there is a need for development of new chemotherapeutic strategies for treatment of C. glabrata disseminated and mucosal infections. The methylcitrate cycle represents an excellent potential target for therapeutic intervention in C. glabrata. The methylcitrate cycle carried out detoxification of propionate and propionyl-CoA, produced endogenously by C. glabrata as a byproduct of the degradation of protein. The cycle degrades propionate to pyruvate in three steps, catalyzed by the Cit3, Pdh1 and Icl2 enzymes. We have shown that the entire methylcitrate cycle is strongly induced following phagocytosis by macrophages. We have also shown that disruption of PDH1 or ICL2 renders C. glabrata exquisitely sensitive to propionate, likely due to the accumulation of the metabolic toxin methylcitrate. We propose first to analyze how flux through the methylcitrate cycle is controlled; specifically we would like to know how, in C. glabrata, propionate is converted to propionyl-CoA, the entry point into the methylcitrate cycle. We hypothesize that this activity is due to dual function acetyl- and propionyl-CoA synthetases encoded by the ACS1 and/or ACS2 genes. We will test this hypothesis and determine if Acs activity controls flux through the pathway and potentiates propionate toxicity. We also have designed a whole cell assay to screen for compounds that inhibit Pdh1 or Icl2. We propose to screen the NCI DTP compound collection for compounds that target either of these enzymes. We will characterize initial hits in several ways. First, we will determine in vitro if the compounds inhibit Pdh1 or Icl2 activity; second we will test positive compounds against the orthologous enzymes of C. albicans or A. fumigatus to assess activity against other important fungal pathogens. This is a high risk project, and a new area of investigation for my lab; identification of compounds that inhibit this cycle will in the future allow characterization of the methylcitrate cycle during infection in both disseminated and mucosal models of infection. Active compounds may also provide a starting point for future development of human therapeutics. PUBLIC HEALTH RELEVANCE: Candida glabrata is an important cause of infection in HIV-positive and HIV-negative individuals. We are studying the methylcitrate cycle in C. glabrata as a potential target for new drugs. We propose screening a large collection of compounds available from the NIH to identify compounds that inhibit this pathway; some of these may ultimately lead to development of new treatments of Candida and other fungal infections.

描述(由申请人提供)：光滑念珠菌是HIV血清阳性和HIV血清阴性人群中的一种重要的机会性病原体。在美国，过去15年的大多数临床研究表明，光滑念珠菌占黏膜和播散性念珠菌感染的15%-20%，光滑念珠菌对三氮唑类抗真菌药物具有天生的耐药性，需要开发新的化疗策略来治疗光滑念珠菌播散性和粘膜感染。柠檬酸甲酯循环是光肩星天牛治疗干预的一个很好的潜在靶点。柠檬酸甲酯循环对丙酸和丙酰-辅酶A进行解毒，丙酰-辅酶A是光滑拟青霉降解蛋白质的副产物，由其内源产生。在Cit3、Pdh1和Icl2酶的催化下，该循环分三步将丙酸降解为丙酮酸。我们已经证明，整个柠檬酸甲酯循环是在巨噬细胞吞噬后强烈诱导的。我们还表明，PDH1或ICL2的干扰使光滑隐翅虫对丙酸非常敏感，这可能是由于代谢毒素柠檬酸甲酯的积累。我们建议首先分析如何控制通过柠檬酸甲酯循环的通量；具体地说，我们想知道在光肩星天牛中，丙酸是如何转化为丙酰辅酶A的，丙酰辅酶A是进入柠檬酸甲酯循环的入口点。我们推测这种活性是由于ACS1和/或ACS2基因编码的乙酰辅酶A合成酶和丙酰辅酶A合成酶的双重功能所致。我们将验证这一假说，并确定ACS活性是否控制通过该途径的流量，并增强丙酸的毒性。我们还设计了一种全细胞试验来筛选抑制Pdh1或Icl2的化合物。我们建议在NCI DTP化合物集合中筛选针对这两种酶的化合物。我们将用几种方式描述最初的热门歌曲。首先，我们将在体外确定这些化合物是否抑制Pdh1或Icl2活性；其次，我们将测试对白色念珠菌或烟曲霉菌的同源酶呈阳性的化合物，以评估其对其他重要真菌病原体的活性。这是一个高风险的项目，也是我的实验室的一个新的研究领域；识别抑制这一循环的化合物将使未来能够在播散性和粘膜感染模型中表征感染期间的柠檬酸甲酯循环。活性化合物也可能为人类治疗学的未来发展提供一个起点。公共卫生相关性：光滑念珠菌是艾滋病毒阳性和艾滋病毒阴性个体感染的重要原因。我们正在研究光肩星天牛体内的柠檬酸甲酯循环，以此作为新药的潜在靶点。我们建议从NIH筛选大量可用化合物来识别抑制这一途径的化合物；其中一些最终可能导致开发治疗念珠菌和其他真菌感染的新方法。