Heme A and cytochrome oxidase biosynthesis

超出提供的空间。细胞色素氧化酶(COX)是线粒体的末端呼吸复合体，由线粒体DNA编码的12-13个亚基组成，其中3个亚基构成酶的催化核心。在酿酒酵母中，复合体的生物发生由大约30多个核基因控制。这些编码包括一组输入亚单位和各种辅助因子，涉及催化亚基的表达、亚基2(铜蛋白)的膜插入和成熟、Hemc A合成、铜稳态，以及目前还不清楚的其他事件。在过去的授权期内，我们1)获得证据证明COX 15P、铁氧还蛋白和铁氧还蛋白还原酶构成三种单加氧酶可将血红素O转化为血红素A的直接前体；2)确定了两个新的基因(COX18、COX20)，它们负责促进亚基2的膜插入和成熟；3)突变体的特征抑制物，其表型涉及亚基1(血红素蛋白)作为Shylp作用的靶标；4)与Pierre Rustin博士和他的同事合作，证明了一个有胎儿神经肌病病史的家庭的COX缺陷是由血红素：法尼基转移酶的突变引起的。我们未来一段时间的目标是完成对hemc A生物合成途径的研究，继续分析Shyi突变体和其余十几个核基因，这些基因在COX组装中的功能仍在很大程度上未知。在血红素A的生物合成方面，我们打算获得铁氧还蛋白参与血红素0羟化的更直接的证据，纯化和鉴定CoxlSp，并鉴定血红素A的羟化前体。其次，我们将通过脉冲追逐实验研究Shy]突变体中的组装中间产物，寻找新的抑制因子，从而更好地了解Shylp的功能。这些研究还应该阐明Leigh综合征的生化基础，已被证明是由Shyi的人类同源基因SURF[1]的突变引起的。结合正在进行的其他COX特异性基因的功能分析，这些研究有望填补我们对HNW的现有理解空白，即重要的pn-zymp被组装在一起。表演网站========================================Section End===========================================

EXCEED THE SPACE PROVIDED. Cytochrome oxidase (COX), the terminal respiratory complex of mitochondria, is composed of 12-13 subunits three of which, encoded by mtDNA, form the catalytic core of the enzyme. In S. cerevisiue, biogenesis of the complex is governed by some 3 dozen nuclear genes. These code for the set of imported subunits and for various accessory factors involved in expression of the catalytic subunits, membrane insertion and maturation of subunit 2 (copper protein), hemc A synthesis, copper homeostasis, and still other events that are poorly defined at present. During the past grant period we 1) obtained evidence that Cox 15p, ferredoxin and ferredoxin reductase constitute a three component monooxygenase that converts heme O to the immediate precursor of heme A, 2) identified two new genes (COX18, COX20) responsible for promoting membrane insertion and maturation of subunit 2, 3) characterized suppressors of shy] mutants whose phenotype implicate subunit 1 (heme protein) as the target of Shylp action, 4) collaborated with Dr. Pierre Rustin and his colleagues in demonstrating that the COX deficiency of a family with a history of a fetal neuromyopathy is caused by a mutation in heme:farnesyl transferase . Our goals for this coming period is to complete studies on the hemc A biosynthetic pathway, to continuethe analysisof shyI mutants and the remaining dozen nuclear genes whose functions in COX assembly remain largely unknown. With respect to heme A biosynthesis, we intend to obtain more direct evidence for the participation of ferredoxin in hydroxylationof hemc 0, to purify and characterize CoxlSp, and to identify the hydroxylated precursor of heme A. Secondly, we will strive to gain better insights into the function of Shylp by examining the assembly intermediates in shy] mutants through pulse-chase experiments and by searching for new suppressors. These studies should also shed light on the biochemical basis of Leigh's syndrome, which has been shown to be caused by mutations in SURF], the human homologue of SHYI. Together with the ongoing functional analysis of other COX-specific genes, these studies are anticipated to fill the existent gaps in our understanding of hnw thk important pn-zymp is assembled. PERFORMANCE SITE ========================================Section End===========================================