GENETIC ANALYSIS OF MG-TETRAPYRROLE BIOSYNTHESIS

MG-四吡咯生物合成的遗传分析

• 批准号: 2430493
• 负责人: CARL Eugene BAUER
• 金额: $ 14.36万
• 依托单位: TRUSTEES OF INDIANA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-06-01 至 2000-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2430493
• 关键词: DNA binding protein; DNA footprinting; Rhodospirillales; atomic absorption spectrometry; bacteria; biosynthesis; chlorophyll; evolution; gel mobility shift assay; gene expression; genetic mapping; genetic promoter element; heme; iron; iron compounds; magnesium; metalloproteins; molecular cloning; nucleic acid sequence; photosynthetic bacteria; posttranscriptional RNA processing; reporter genes; site directed mutagenesis; tetrapyrroles; transcription factor

The complex tetrapyrrole biosynthetic pathway is responsible for synthesizing important metabolites such as vitamin B12, hemes, bilins and chlorophylls. The "common trunk" of the pathway from 5-aminolevulinate to protoporphyrin IX, has received the most attention owing to the fact that a number of heredity diseases (porphyrias) are caused by the overproduction of heme precursors. Clinical manifestations of overproducing these intermediates range from simple skin lesions, to psychotic disorders, to death. The vitamin B12 branch of the pathway has also received considerable attention as of late. Many genes involved in vitamin B12 synthesis have been identified in Pseudomonas dentrificans and in Salmonella typhimurium. In contrast to the information on heme and vitamin B12 synthesis, there is little information on genes which control synthesis of the Mg-tetrapyrrole branch which is responsible for synthesis of chlorophylls and bacteriochlorophylls. In this proposal we plan to perform detailed biochemical and genetic analysis of the Mg-tetrapyrrole biosynthetic pathway from the bacterium Rhodobacter capsulatus. This includes (i) Biochemical characterization of enzymes from the Mg-tetrapyrrole branch of the biosynthetic pathway, (ii) Biochemical and genetic characterization of a redox responding transcription factor that regulates expression of heme, Mg-tetrapyrrole and carotenoid biosynthesis genes as well as polypeptides that comprise the light harvesting-II portion of the photosystem. (iii). Characterization of additional transcriptional and post-transcriptional regulatory factors that controls the flow of intermediates through this branch of the tetrapyrrole biosynthetic pathway. (iv) Investigations on Mg-tetrapyrrole biosynthesis in the cyanobacterium Synechocystis PCC 6803 will also be initiated for use in a comparative analysis as well as a model system for Mg-tetrapyrrole biosynthesis in eukaryotes. A thorough understanding of the tetrapyrrole biosynthetic pathway has some far ranging practical implications beyond an academic philosophical interest. These include some obvious commercial applications, such as the design of herbicides that target enzymes in the Mg tetrapyrrole pathway, and the health implications of overproducing tetrapyrrole endproducts such as vitamin B12 and heme. It should also not be overlooked that tetrapyrrole driven photosynthesis is the primary route of capturing and supplying energy to living cells and, consequently, it is the most important source of energy in our technological world.

复杂的四吡咯生物合成途径负责 合成重要的代谢物，如维生素B12，血红素，胆色素和 叶绿素从5-氨基乙酰丙酸到 原卟啉IX，由于以下事实而受到最多的关注： 许多遗传性疾病（卟啉症）是由 血红素前体的过量产生。临床表现 过度产生这些中间产物的范围从简单的皮肤损伤， 精神失常致死该途径的维生素B12分支具有 最近也受到了很大的关注。许多基因参与了 维生素B12的合成已经在树枝状假单胞菌中被鉴定， 鼠伤寒沙门氏菌与血红素和 维生素B12的合成，很少有关于基因的信息，控制 负责合成的Mg-四吡咯分支的合成 叶绿素和细菌叶绿素。 在这项提案中，我们计划进行详细的生化和遗传 四吡咯镁生物合成途径分析 荚膜红杆菌 这包括（i）生物化学表征 来自生物合成途径的Mg-四吡咯分支的酶，（ii） 氧化还原反应的生化和遗传特征 一种调节血红素表达的转录因子，Mg-四吡咯 和类胡萝卜素生物合成基因以及多肽， 光系统的光收集-II部分。 （三）. 额外的转录和转录后的表征 调节因子，控制中间体的流动，通过这个 四吡咯生物合成途径的分支。(iv)调查 蓝细菌集胞藻PCC 6803中镁-四吡咯的生物合成 还将开始进行比较分析， 真核生物中镁-四吡咯生物合成的模型系统。 对四吡咯生物合成途径的透彻理解有一些 超越学术哲学的广泛的实践意义 兴趣其中包括一些明显的商业应用，例如 设计以四吡咯镁途径中的酶为靶标的除草剂， 以及过量生产四吡咯终产物对健康的影响， 维生素B12和血红素同样不容忽视的是， 四吡咯驱动的光合作用是捕获和 为活细胞提供能量，因此，它是最 是我们科技世界中重要的能源。