Eukaryotic Heme Utilization

真核血红素利用

• 批准号: 8553535
• 负责人: Caroline Philpott
• 金额: $ 30.95万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 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/8553535
• 关键词: Binding; Biochemical; Biological; Caenorhabditis elegans; Cells; Collaborations; Copper; Cytosol; Environment; Enzymes; Eukaryota; Exhibits; Friedreich Ataxia; Genes; Genetic; Genetic Screening; Heme; Heme Iron; Hemoglobin; Hereditary Disease; Hereditary hemochromatosis; Homeostasis; Human; Hypoxia; Intracellular Transport; Iron; Iron Compounds; Iron Overload; Mammals; Maryland; Metabolism; Microarray Analysis; Mitochondria; Myoglobin; Nutrient; Organic Iron Compounds; Organism; Oxygen; Process; Regulation; Role; Saccharomyces cerevisiae; Saccharomycetales; Site; System; Toxin; Universities; Yeasts; Zinc; aqueous; cofactor; deprivation; design; heme a; human disease; insight; iron metabolism; loss of function; metal metabolism; microorganism; mutant; response; trafficking; uptake; yeast protein

Very little is known about heme transport in eukaryotes and a heme-specific transport uptake systems have not been identified in yeast. Although S. cerevisiae does not take up heme in response to iron deprivation, we have determined that this species does have an inducible heme uptake system that is activated under heme deficiency and hypoxic conditions. We performed microarray analysis of strains grown under these conditions, and found that a number of putative transporters are transcriptionally activated. Heme is synthesized in mitochondria, yet the cofactor is used in compartments throughout the cell. Heme is highly hydrophobic and is unlikely to be released into the aqueous environment of the cytosol, suggesting that mechanisms exist for the intracellular trafficking of heme. We have designed a genetic screen for the identification of yeast proteins involved in intracellular heme trafficking and are evaluating candidates. Genes identified in this screen suggest that heme moves from the mitochondria to other sites through the vesicular trafficking system. In collaboration with Iqbal Hamza of the University of Maryland, we are functionally characterizing the putative heme transporters of C. elegans by expressing them in yeast. Heme transporters from C. elegans have heme uptake activity when expressed in yeast and mutant forms of heme transporters exhibit loss of function when expressed in yeast.

关于真核生物中血红素的转运知之甚少，并且尚未在酵母中鉴定出血红素特异性转运摄取系统。尽管酿酒酵母不会因缺铁而摄取血红素，但我们已经确定该物种确实具有在血红素缺乏和缺氧条件下激活的诱导型血红素摄取系统。我们对在这些条件下生长的菌株进行了微阵列分析，发现许多假定的转运蛋白被转录激活。 血红素在线粒体中合成，而辅因子则在整个细胞的区室中使用。血红素具有高度疏水性，不太可能释放到细胞质的水环境中，这表明存在血红素细胞内运输的机制。我们设计了一种遗传筛选来鉴定参与细胞内血红素运输的酵母蛋白，并正在评估候选蛋白。该筛选中鉴定的基因表明血红素通过囊泡运输系统从线粒体转移到其他位点。 我们与马里兰大学的 Iqbal Hamza 合作，通过在酵母中表达线虫的假定血红素转运蛋白来对其进行功能表征。来自线虫的血红素转运蛋白在酵母中表达时具有血红素摄取活性，而突变形式的血红素转运蛋白在酵母中表达时表现出功能丧失。