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运输知之甚少，酵母中尚未确定血红素特异性的运输吸收系统。尽管酿酒酵母对铁的剥夺没有血红素，但我们已经确定该物种确实具有可诱导的血红素摄取系统，该系统在血红素缺乏症和低氧条件下被激活。我们对在这些条件下生长的菌株进行了微阵列分析，发现许多推定的转运蛋白被转录激活。 血红素是在线粒体中合成的，但辅因子在整个细胞的隔室中使用。血红素是高度疏水性的，不太可能被释放到细胞质的水性环境中，这表明存在血红素内细胞内运输的机制。我们设计了一个遗传筛选，用于鉴定参与细胞内血红素运输的酵母蛋白，并正在评估候选者。在此屏幕上鉴定出的基因表明，血红素通过囊泡运输系统从线粒体移动到其他部位。 与马里兰大学的伊克巴尔·哈姆扎（Iqbal Hamza）合作，我们在功能上通过在酵母中表达秀丽隐杆线虫的假定的血红素转运蛋白。当以酵母和突变形式的血红素转运蛋白表达时，来自秀丽隐杆线虫的血红素转运蛋白具有血红素摄取活性，当在酵母中表达时表现出功能丧失。