权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Physiological function of respiratory enzymes specific for parasite mitochondria in the adaptation to low oxygen tension

寄生虫线粒体特异性呼吸酶在适应低氧张力中的生理功能

基本信息

批准号：
13854011
负责人：
KITA Kiyoshi
金额：
$ 62.9万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (S)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13854011/
关键词：
mitochondria complex II NADH-fumarate reductase Ascaris suum parasite crystal structure analysis adaptation to low oxygen tension biosynthesis of ubiquinone NADH-フアル酸還元系 HIF-1 呼吸鎖フマル酸還元酵素ロドキノン

项目摘要

Our studies on respiratory chain of the parasitic helminth, A. suum, has shown that the mitochondrial NA DH-fumarate reductase system plays an important role in the anaerobic energy metabolism of adult parasites inhabiting hosts as well as unique features of the developmental changes that occur during their life cycle. In this system, the reducing equivalent of NA DH is transferred to the low-potential rhodoquinone (RQ) by the NADH-RQ reductase complex (Complex I). This pathway ends with the production of succinate by the quinol-fumarate reductase activity of complex II (succinate-ubiquinone reductase in aerobic respiration). Electron transfer from NA DH to fumarate is coupled to site I phosphorylation of complex I via generation of a proton motive force, which is sufficiently high to drive ATP synthesis.Kinetic analysis of Complex I along with the fact that helminth complex I uses both rhodoquinone-9 (RQ_9) and ubiquinone-9 (UQ_9) as an electron acceptor suggest that the structural features of the quinone reduction site of helminth complex I may differ from that of mammalian complex I. In fact, the inhibitory mechanism of quinazolines was competitive and partially competitive against RQ_2 and UQ_2, respectively.Recently study showed that A. suum mitochondria express stage-specific isoforms of complex II: the flavoprotein subunit and the small subunit of cytochrome b (CybS) of the larval complex II differ from those of adult enzyme, while two complex II's share a common iron-sulfur cluster subunit (Ip). Enzymatic assays revealed that the adult and larval A. suum complex II's have different properties than the complex II of the mammalian host and that the larval complex II is able to function as a RQ-fumarate reductase. Most potent inhibitor of complex II, Atpenin A5 was found during the screening of inhibitors for A. suum complex II. We obtained a crystal of adult complex II for the first example of mitochondrial RQ-fumarate reductase.

本文对寄生蠕虫A. suum等人的研究表明，线粒体NA DH-延胡索酸还原酶系统在寄生于宿主的成虫的无氧能量代谢中起重要作用，并且在其生命周期中发生的发育变化的独特特征中起重要作用。在该系统中，NADH的还原当量通过NADH-RQ还原酶复合物（复合物I）转移到低电位的玫瑰醌（RQ）。该途径以通过复合物II（有氧呼吸中的琥珀酸-泛醌还原酶）的喹啉-富马酸还原酶活性产生琥珀酸而结束。从NADH到富马酸盐的电子转移通过产生质子动力与复合物I的位点I磷酸化偶联，复合物I的动力学分析沿着蠕虫复合物I同时使用玫瑰醌-9（RQ_9）和泛醌-9（UQ_9）的事实。作为电子受体，表明蠕虫复合物I的醌还原位点的结构特征可能不同于哺乳动物复合物I。事实上，喹唑啉类化合物对RQ_2和UQ_2的抑制机制分别为竞争性和部分竞争性。猪线粒体表达复合物II的阶段特异性同种型：幼虫复合物II的黄素蛋白亚基和细胞色素B小亚基（CybS）不同于成虫酶，而两个复合物II共享一个共同的铁硫簇亚基（Ip）。酶活性测定结果表明，A.猪复合物II具有与哺乳动物宿主的复合物II不同的性质，并且幼虫复合物II能够起到RQ-延胡索酸还原酶的作用。在筛选A抑制剂的过程中发现了复合物II的最有效抑制剂Atpenin A5。suum complex II.我们获得了成人复合物II的第一个例子的线粒体RQ-延胡索酸还原酶的晶体。