PHOSPHOLIPIDS AND MITOCHONDRIAL FUNCTION

磷脂和线粒体功能

• 批准号: 6019344
• 负责人: WILLIAM DOWHAN
• 金额: $ 26.27万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2002-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6019344
• 关键词: Saccharomyces cerevisiae; cardiolipins; enzyme mechanism; gene deletion mutation; gene expression; genetic regulation; genetic transcription; genetic translation; mitochondria; molecular biology; phospholipids; protein biosynthesis; protein purification

DESCRIPTION: (adapted from applicant's abstract) Significant reduction of mitochondrial cardiolipin (CL) has been postulated to compromise directly cytochrome oxidase function, the ADP/ATP translocator, phosphate translocator, ATP synthase, palmitoyl carnitine transferase, and carnitine translocase. Inhibition of any of these processes would lead to mitochondrial dysfunction particularly in the process of oxidative phosphorylation. Compromising terminal oxidation has been shown to accentuate both short term and long term oxidative damage to tissue because of the build up of highly reactive intermediates generated by the electron transport chain leading to even further damage. With aging the cholesterol to phospholipid ratio of heart muscle mitochondrial increases due to loss of CL which has been associated with increases in membrane rigidity. To date there is no genetic evidence for any of the critical roles with which CL has been associated, and the lack of mutants in the synthesis of CL in eukaryotic cells has made it difficult to reconcile in vitro observations of the role of CL with in vivo processes. We have isolated the genes (PGSI and CLS1) from Saccharomyces cerevisiae that encode the phosphatidylglycerol-(PG) phosphate (P) and CL synthases, which are responsible for the synthesis of CL in mitochondria. By making mutants null in the these genes, the requirement for PG/CL for both cell viability and mitochondrial function will be established. Using these null mutants and strains in which the expression of these genes are artificially regulated, the cellular processes dependent on PG and/or CL will be identified and their requirement for these lipids will be detailed at the molecular level. Since CL appears to be a critical for phospholipid to mitochondrial function, understanding the regulation of its synthesis is important to a better understanding of the relationship between variation in CL levels and cellular dysfunction. The regulation at the level of transcription and translation of these genes will be investigated to gain insight into CL homeostasis. Additional insight into CL regulation will be obtained by purifying and characterizing the enzymological properties of the PG-P synthase, which is the rate limiting enzyme in CL synthesis, as well as the CL synthase, the terminal step in CL synthesis. Given the complexity of molecular genetic and biochemical studies in somatic cells and the similarity of apparent CL function in all eukaryotic cells, the detailed studies of CL synthesis and function in yeast will lead to a clearer understanding of the function of this phospholipid in all eukaryotic cells.

描述：（改编自申请人摘要）显著降低 线粒体心磷脂（CL）的作用被认为是 直接细胞色素氧化酶功能，ADP/ATP转运蛋白， 磷酸转运蛋白，ATP合成酶，棕榈酰肉毒碱转移酶， 和肉毒碱移位酶。 抑制这些过程中的任何一个， 导致线粒体功能障碍，特别是在 氧化磷酸化 危害终端氧化已被 显示出加重短期和长期氧化损伤， 由于高活性中间体的积累， 产生的电子传递链导致甚至进一步 损害 随着年龄的增长， 肌肉线粒体增加，由于失去CL，这已经是 与膜刚性的增加有关。 迄今为止还没有 遗传证据的任何关键作用，其中CL已 相关的，和缺乏突变体的合成CL在真核生物 细胞使得很难在体外观察到 CL在体内过程中的作用。 我们已经分离了基因（PGSI和 CLS 1），其编码 磷脂酰甘油-（PG）磷酸（P）和CL磷酸化酶，它们是 负责线粒体中CL的合成。 通过制造变种人 如果这些基因无效，则两种细胞都需要PG/CL， 将建立存活力和线粒体功能。 使用这些 无效突变体和菌株，其中这些基因的表达是 人工调控，细胞过程依赖于PG和/或 将确定CL，并确定其对这些脂质的需求 在分子水平上详细描述。 由于CL似乎是一个关键的 磷脂对线粒体功能的调节，了解 它的综合对于更好地理解 CL水平的变化和细胞功能障碍之间的关系。 调控 在这些基因的转录和翻译水平上， 研究以深入了解CL稳态。 额外的洞察力 CL调节将通过纯化和表征 PG-P合成酶的酶学性质，这是速率 CL合成中的限制酶，以及CL合成酶， CL合成的最终步骤。 考虑到分子结构的复杂性 体细胞的遗传和生物化学研究， 在所有真核细胞中明显的CL功能， CL在酵母中的合成和功能将导致更清晰的理解 磷脂在所有真核细胞中的功能。