Cytochrome c biogenesis

描述(由申请人提供)：细胞色素是大多数生物体中有氧和无氧电子传输所必需的血红素蛋白。虽然这些蛋白质中的许多结构和功能已经被研究了50多年，但直到最近才变得清楚，细胞色素通常需要组装因子。这种组装因子在某些人类疾病中是有缺陷的，对许多病原体的生长是必不可少的。C型细胞色素的生物发生需要大量的因素，并且可以通过三种系统中的任何一种来进行。原核生物、植物线粒体和叶绿体使用系统I或系统II，据预测，这两个系统都需要专门的机制来运送血红素和细胞色素硫醇还原。在真菌、无脊椎动物和脊椎动物的线粒体中特异进化的系统III中，线粒体膜间隙中的一种称为细胞色素C-血红素裂解酶的酶起着关键作用。细胞色素c的生物发生需要9个系统I和至少3个系统II的专用、完整的膜蛋白。本建议的目的是了解系统I和II使用三个模型变形杆菌的分子机制：胶囊红杆菌(系统I)、百日咳杆菌(系统II)和大肠杆菌(系统I和重组系统II)。具体地说，目的是(1)鉴定和表征百日咳杆菌新的系统II基因；(2)利用系统I和系统II重建体外生物发生；(3)确定底物识别要求(即。系统I和系统II所必需的生理条件；(4)对系统I和系统II涉及的关键蛋白质进行功能分析。

DESCRIPTION (provided by applicant): Cytochromes are heme proteins essential for aerobic and anaerobic electron transport in most organisms. While the structures and functions of many of these proteins have been studied for over fifty years, only relatively recently has it become clear that cytochromes often require assembly factors. Such assembly factors are defective in certain human disorders, and essential for growth in many pathogens. Biogenesis of the c-type cytochromes requires a large number of factors and can proceed by any one of three systems. Prokaryotes, plant mitochondria, and chloroplasts use either system I or II, which are each predicted to require dedicated mechanisms for heme delivery and apocytochrome thiolreduction. In system III, which has specifically evolved in the mitochondna of fungi, invertebrates, and vertebrates, a pivotal role is played by a single enzyme called cytochrome c heme lyase in the mitochondrial intermembrane space. Cytochrome c biogenesis requires nine dedicated, integral membrane proteins for System I and at least three for System II. The goals of this proposal are to understand the molecular mechanisms by which Systems I and II operate using three model proteobacteria, Rhodobacter capsulatus (System I), Bordetella pertussis (System II), and Escherichia coli (System I and recombinant System II). Specifically, aims are to (1) identify and characterize novel System II genes in B. pertussis; (2) reconstitute in vitro biogenesis using System I and System II; (3) determine the substrate recognition requirements (ie. apocytocbrome and heme) and the physiological conditions essential for System I and II; (4) carry out a functional analysis of key proteins involved in System I and II.