HUMAN MITOCHONDRIAL FOLATE/ANTIFOLATE TRANSPORT

人体线粒体叶酸/抗叶酸转运

• 批准号: 7218711
• 负责人: RICHARD G MORAN
• 金额: $ 23.03万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2009-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7218711
• 关键词: Anions; Antimetabolites; Binding; Binding Sites; Biochemistry; Carrier Proteins; Cells; Class; Complementary DNA; Computer Simulation; Cytosol; Data; Disease; Epitope Mapping; Folate; Folic Acid Antagonists; Folic Acid Deficiency; Fungal Genome; Gene Family; Genetically Engineered Mouse; Glycine; Goals; Hereditary Disease; Human; Human Genetics; Inner mitochondrial membrane; Interruption; Knock-out; Lead; Libraries; Malignant Neoplasms; Mammalian Cell; Maps; Mass Spectrum Analysis; Mediating; Membrane; Metabolic; Mitochondria; Mitochondrial Matrix; Mitochondrial Proteins; Modeling; Mus; Mutagenesis; Mutate; Mutation; Outer Mitochondrial Membrane; Penetration; Peptides; Phenotype; Play; Polymerase Chain Reaction; Process; Protein Binding; Proteins; Proteolipids; Reaction; Recombinant Proteins; Recombinants; Resistance; Role; SLC19A1 gene; Site-Directed Mutagenesis; Structure; Substrate Specificity; System; Tetrahydrofolates; Time; Toxic effect; Transmembrane Domain; Transport Process; Work; cofactor; crosslink; domain mapping; folic acid metabolism; human disease; inhibitor/antagonist; knockout animal; man; member; novel; proteoliposomes; reconstitution; research study; two-dimensional; voltage

DESCRIPTION (provided by applicant): The inner membrane of the mitochondria has several embedded transport proteins that facilitate the translocation of metabolites and cofactors into the mitochondria. These proteins work in concert with mechanisms in the outer membrane to bring cationic and anionic metabolic intermediates from the cytosol to the matrix of mammalian cells. There are 35 inner mitochondrial wall transporters recognizable in the yeast genome; the function of only 13 are known. We have recently cloned a cDNA that encodes an inner mitochondrial protein that facilitates the transport of folate cofactors into the mitochondria. There are data suggesting that a component of the toxicity of the tetrahydrofolate antimetabolites seen in man may be due to inhibition of this transporter. Mammalian cells deficient in this transporter cannot survive in the absence of glycine. In this application, we propose to study the mechanism of this transporter, defining the substrate specificity for the various forms of the folates found in cells and also for the various antifolates that have been used to treat human cancers. Transport process will be studied in isolated mitochondria and in recombinant protein reconstituted into proteolipid bilayers. The proteins in the outer and inner mitochondrial membrane that bind folates will be defined, as will any binding partners involved in the transport through inner or outer membrane of the mitochondria. The phenotype of mice genetically engineered to lack this transporter will be studied as a model for human genetic deficiencies of mitochondrial folate transport. The binding site for folates in this transporter and the orientation of the transmembrane domains will be determined by site-directed mutagenesis, random mutagenesis of peptides, and epitope mapping. These studies will lead to an understanding of the basic biochemistry of this transport process and will lead to an understanding of the role of the inner membrane folate transporter in antifolate toxicity and in human genetic disorders of folate metabolism.

描述（由申请人提供）：线粒体的内膜具有多种嵌入的转运蛋白，促进代谢物和辅助因子易位到线粒体中。这些蛋白质与外膜中的机制协同工作，将阳离子和阴离子代谢中间体从细胞质带到哺乳动物细胞的基质。酵母基因组中有 35 个可识别的线粒体内壁转运蛋白；已知的功能只有 13 个。我们最近克隆了一种编码线粒体内蛋白的 cDNA，该蛋白有助于叶酸辅助因子转运到线粒体中。有数据表明，四氢叶酸抗代谢物对人体的毒性部分可能是由于抑制了这种转运蛋白。缺乏这种转运蛋白的哺乳动物细胞在没有甘氨酸的情况下无法生存。 在此应用中，我们建议研究这种转运蛋白的机制，定义细胞中发现的各种形式的叶酸以及用于治疗人类癌症的各种抗叶酸剂的底物特异性。将在分离的线粒体和重组蛋白重组为蛋白脂质双层中研究运输过程。将定义线粒体外膜和内膜中结合叶酸的蛋白质，以及参与通过线粒体内膜或外膜运输的任何结合伙伴。通过基因工程改造缺乏这种转运蛋白的小鼠的表型将作为人类线粒体叶酸转运遗传缺陷的模型进行研究。该转运蛋白中叶酸的结合位点和跨膜结构域的方向将通过定点诱变、肽的随机诱变和表位作图来确定。 这些研究将有助于了解这种转运过程的基本生物化学，并将有助于了解内膜叶酸转运蛋白在抗叶酸毒性和人类叶酸代谢遗传性疾病中的作用。