HEME BIOSYNTHESIS--C5 PATHWAY TO 5 AMINOLEVULINATE

血红素生物合成--5 氨基乙酰丙酸的 C5 途径

• 批准号: 3756026
• 负责人: CHARLOTTE S RUSSEL
• 金额: --
• 依托单位: CITY COLLEGE OF NEW YORK
• 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/3756026
• 关键词: 5 aminolevulinate synthase; Escherichia coli; aminohydrolases; complement pathway; enzyme activity; gene expression; genetic regulation; genetic transcription; genetic translation; heme; molecular cloning; porphobilinogen; porphyrin biosynthesis

Heme Biosynthesis in Escherichia coli Heme and its related cyclic tetrapyrroles are the prosthetic groups of the hemoglobins, cytochromes, peroxidases, chlorophylls and Vitamin B12. Many of the steps in the biosynthetic pathway of the cyclic tetrapyrroles are highly conserved. The pathway, by necessity is under light metabolic control. Some of the mechanisms of control in various organisms are under active investigation. In the process of cloning and sequencing two genes of the heme biosynthetic pathway hemA and hemB, we demonstrated a unique mechanism of control of the activity of porphobilinogen deaminase (PBG-D), a key enzyme in the pathway, namely that the expression of hemB is required for the activity of PBG-D. In addition, we are actively investigating the control of expression of the genes involved in the synthesis of the first committed intermediate of the pathway, 5- aminolevulinic acid (ALA). We elucidated the pathway of the biosynthesis of ALA in E. coli and showed by both biochemical and genetic techniques that ALA is made by the C5 pathway and not by the C4 as previously believed. We have also identified and characterized a hemE mutant and are in the process of cloning and sequencing it. We have over-expressed hemB, the structural gene for ALA dehydratase and characterized this enzyme. It is proposed to clone the rest of the uncloned genes of heme biosynthesis in E. coli and to study by in vivo and in vitro techniques, the control (transcriptional, translational and enzymatic) of the heme biosynthesis pathway.

大肠杆菌中的血红素生物合成 血红素及其相关的环状四吡咯是以下辅基 血红蛋白、细胞色素、过氧化物酶、叶绿素和维生素 B12。 环状四吡咯生物合成途径中的许多步骤 是高度保守的。 该途径必然处于光代谢状态 控制。 各种生物体的一些控制机制是 正在积极调查中。 在克隆和测序过程中两个 血红素生物合成途径 hemA 和 hemB 的基因，我们证明了 胆色素原脱氨酶活性控制的独特机制 (PBG-D)，该途径中的关键酶，即hemB的表达 是 PBG-D 活性所必需的。 此外，我们还积极 研究相关基因的表达控制 该途径的第一个特定中间体的合成，5- 氨基乙酰丙酸（ALA）。 我们阐明了生物合成途径 大肠杆菌中的 ALA 含量并通过生化和遗传技术显示 ALA 是由 C5 途径产生的，而不是像之前那样由 C4 产生 相信。 我们还鉴定并表征了 hemE 突变体 正在对其进行克隆和测序。 我们已经过度表达了 hemB，ALA 脱水酶的结构基因，并对其进行了表征 酶。 建议克隆其余未克隆的血红素基因 大肠杆菌中的生物合成并通过体内和体外技术进行研究， 血红素的控制（转录、翻译和酶促） 生物合成途径。