Oxygen-Mediated Regulation of Tetrapyrrole Synthesis in Rhodobacter Capsulatus

氧介导的荚膜红杆菌四吡咯合成调控

• 批准号: 9304999
• 负责人: Alan Biel
• 金额: $ 24万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-09-01 至 1998-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9304999&HistoricalAwards=false
• 关键词: Oxygen; Mediated; Regulation; Tetrapyrrole; Synthesis

9304999 Biel The ultimate objective of this research is to elucidate the mechanism by which oxygen regulates tetrapyrrole biosynthesis in Rhodobacter capsulatus. Recent evidence has suggested that the condensation of two aminolevulinate molecules to form the first pyrrolic intermediate, porphobilinogen, is regulated by oxygen. This step is catalyzed by the enzyme prophobilinogen synthase, the product of the hemB gene. The research described in this proposal seeks to determine whether oxygen regulates transcription of the hemB gene, which encodes porphobilinogen synthase, or the activity of this enzyme, or both. Transcriptional regulation of the hemB gene will be investigated by measuring hemB mRNA production and degradation in cultures grown under high and low oxygen. Oxygen- mediated regulation of porphobilinogen synthase activity will be measured by following the kinetics of protoporphyrin formation during a shift-up in oxygen tension. If oxygen regulates porphobilinogen synthase activity, protoporphyrin accumulation should stop immediately upon oxygenation of the culture. Antibodies against porphobilinogen synthase will be used to determine if oxygen causes increased degradation of the enzyme. %%% In the photosynthetic bacterium Rhodobacter capsulatus, a single branched pathway is used to make heme and bacteriochlorophyll. Oxygen greatly reduced the expression of this pathway. The step at which oxygen regulates this pathway has been located, and the research described in this proposal seeks to determine whether oxygen regulates the synthesis of the enzyme porphobilinogen synthase, the activity of the enzyme, or both. ***

9304999 Biel 这项研究的最终目的是阐明氧调节荚膜红杆菌中四吡咯生物合成的机制。 最近的证据表明，两个氨基乙酰丙酸分子缩合形成第一个吡咯中间体胆色素原受到氧的调节。 该步骤由原胆原合酶（hemB 基因的产物）催化。 该提案中描述的研究旨在确定氧气是否调节编码胆色素原合酶的 hemB 基因的转录或该酶的活性，或两者兼而有之。 通过测量在高氧和低氧条件下生长的培养物中 hemB mRNA 的产生和降解，可以研究 hemB 基因的转录调控。 氧介导的胆色素原合酶活性调节将通过跟踪氧张力升高过程中原卟啉形成的动力学来测量。 如果氧气调节胆色素原合酶活性，则原卟啉积累应在培养物充氧后立即停止。 抗胆色素原合酶的抗体将用于确定氧气是否导致酶的降解增加。 %%% 在光合细菌荚膜红杆菌中，单分支途径用于制造血红素和细菌叶绿素。 氧气大大降低了该途径的表达。 氧调节该途径的步骤已被定位，本提案中描述的研究旨在确定氧是否调节胆色素原合酶的合成、酶的活性或两者。 ***