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：(改编自申请人的摘要)显著减少 线粒体心磷脂(CL)的活性已被假定为妥协 直接作用于细胞色素氧化酶，ADP/ATP转运体， 磷酸转运体，三磷酸腺苷合成酶，棕榈酰肉碱转移酶， 和肉碱转位酶。抑制这些过程中的任何一个都会 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 被证明会加剧短期和长期的氧化损伤 由于高活性中间体的积聚而形成的组织 由电子传输链产生，导致更进一步 损坏。心脏胆固醇/磷脂比值随增龄变化 肌肉线粒体增加是由于CL的丢失，而CL已经 与膜硬度的增加有关。到目前为止还没有 CL所扮演的任何关键角色的遗传证据 真核细胞中CL合成中的联合和缺失突变体 细胞已经很难协调体外观察到的 CL在体内过程中的作用。我们已经分离出了基因(pGSI和 Cls1)从酿酒酵母中分离出来的 磷脂酰甘油-(PG)磷酸(P)和CL合成酶，它们是 负责线粒体中CL的合成。通过制造突变体 在这些基因中为空，两个细胞都需要PG/CL 生存能力和线粒体功能将被建立。使用这些 表达这些基因的零突变体和菌株 人工调节的细胞过程依赖于PG和/或 将确定CL，他们对这些脂类的需求将是 在分子水平上有详细的描述。因为CL似乎是一个关键 磷脂对线粒体功能的调节作用 它的综合对于更好地理解这一关系是重要的 CL水平的变化和细胞功能障碍之间的关系。这项规定 在转录和翻译这些基因的水平上 调查以深入了解CL的动态平衡。其他洞察力 转化为CL调节将通过提纯和表征 PG-P合成酶的酶学性质，即 CL合成中的限制性酶，以及CL合成酶， CL合成的最后一步。考虑到分子的复杂性 体细胞的遗传和生化研究及其相似性 在所有真核细胞中的明显CL功能，详细研究 酵母中CL的合成和功能将使我们更清楚地了解 这种磷脂在所有真核细胞中的功能。