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: 7620189
• 负责人: Brendan Cormack
• 金额: $ 22.74万
• 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 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7620189
• 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（由申请方提供）：光滑念珠菌是HIV血清阳性和HIV血清阴性人群中的重要机会致病菌。在美国，过去15年的大多数临床系列研究表明，C。光滑念珠菌占粘膜和播散性念珠菌病的15-20%，C.光滑念珠菌对三唑类抗真菌药物具有天然耐药性，因此需要开发新的化疗策略来治疗光滑念珠菌。光滑散布和粘膜感染。柠檬酸甲酯循环是一个很好的潜在的治疗目标，在C。光滑的柠檬酸甲酯循环对丙酸和丙酰辅酶A进行解毒，丙酸和丙酰辅酶A由C. glabrata作为蛋白质降解的副产品。该循环在Cit 3、Pdh 1和Icl 2酶的催化下分三步将丙酸降解为丙酮酸。我们已经表明，整个柠檬酸甲酯循环强烈诱导巨噬细胞的吞噬作用。我们还表明，破坏PDH 1或ICL 2使C. glabrata微妙敏感丙酸，可能是由于积累的代谢毒素柠檬酸甲酯。我们建议首先分析如何通过柠檬酸甲酯循环流量控制，具体来说，我们想知道如何，在C。glabrata，丙酸转化为丙酰辅酶A，进入柠檬酸甲酯循环的入口点。我们推测，这种活性是由于双功能乙酰-和丙酰-CoA合成酶编码的ACS 1和/或ACS 2基因。我们将测试这一假设，并确定是否Acs活性控制通过该途径的流量和增强丙酸盐的毒性。我们还设计了一种全细胞试验来筛选抑制Pdh 1或Icl 2的化合物。我们建议筛选NCI DTP化合物集合中靶向这些酶的化合物。我们将以几种方式描述初始命中。首先，我们将在体外确定化合物是否抑制Pdh 1或Icl 2活性;其次，我们将测试阳性化合物对C. albicans或A. fumigatus来评估对其他重要真菌病原体的活性。这是一个高风险项目，也是我实验室研究的一个新领域;鉴定抑制该循环的化合物将在未来允许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。活性化合物还可以为人类治疗剂的未来发展提供起点。公共卫生相关性：光滑念珠菌是HIV阳性和HIV阴性个体感染的重要原因。我们正在研究C中的柠檬酸甲酯循环。glabrata作为新药的潜在靶点。我们建议筛选大量可从NIH获得的化合物，以确定抑制该途径的化合物;其中一些可能最终导致念珠菌和其他真菌感染的新治疗方法的开发。