The membrane-attached electron carrier cytochrome cy from Rhodobacter sphaeroides is functional in respiratory but not in photosynthetic electron transfer.
The membrane-attached electron carrier cytochrome cy from Rhodobacter sphaeroides is functional in respiratory but not in photosynthetic electron transfer.
复制标题
来自球形红杆菌的膜附着电子载体细胞色素 cy 在呼吸中起作用，但在光合电子转移中不起作用。
DOI：
10.1073/pnas.96.8.4348
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发表时间：
1999
影响因子：
11.1
通讯作者：
Daldal,F
中科院分区：
文献类型：
--
作者：
Myllykallio,H;Zannoni,D;Daldal,F
细胞色素是细胞内普遍存在的电子载体，在细胞能量和信号转导中起重要作用，是研究细胞色素结构和功能的重要模式生物。在这些物种中，Rhodobacter capsulatus具有周质Cytc2Rc和膜结合的二分CytcyRc。这些电子载体参与呼吸和光合电子传递链。另一方面，直到最近，球形红细菌被认为只有这两种细胞色素中的一种，即可溶性Cytc2Rs。最近的工作表明，该物种有一个基因，cycYRs，这是高度同源tocycYRc，在这里提出的工作，其基因产物（CytcyRs）的功能特性的定义。CytcyRsis不参与光合作用的电子传递，但与itsR不同，它在呼吸电子传递中具有活性。capsulatuscounterpart，CytcyRc.嵌合构建体已经表明，CytcyRsis的光合能力丧失至少部分是由其氧化还原活性亚结构域引起的，该亚结构域携带共价结合的血红素。因此，似乎这个结构域与不同的氧化还原伙伴（如光化学反应中心和Cytcoxidase）进行不同的相互作用，并允许细菌在不同的生长条件下有效地将电子汇集到各种目的地。这些发现提出了一个关于细胞凋亡的有趣的进化问题：为什么高等生物的线粒体不像它们的细菌祖先，在呼吸电子传递链中只使用一种可溶性电子载体？
Rhodobacterspecies are useful model organisms for studying the structure and function ofctype cytochromes (Cytc), which are ubiquitous electron carriers with essential functions in cellular energy and signal transduction. Among these species,Rhodobacter capsulatushas a periplasmic Cytc2Rcand a membrane-bound bipartite CytcyRc. These electron carriers participate in both respiratory and photosynthetic electron-transfer chains. On the other hand, until recently,Rhodobacter sphaeroideswas thought to have only one of these two cytochromes, the soluble Cytc2Rs. Recent work indicated that this species has a gene,cycYRs, that is highly homologous tocycYRc, and in the work presented here, functional properties of its gene product (CytcyRs) are defined. It was found that CytcyRsis unable to participate in photosynthetic electron transfer, although it is active in respiratory electron transfer, unlike itsR. capsulatuscounterpart, CytcyRc. Chimeric constructs have shown that the photosynthetic incapability of CytcyRsis caused, at least in part, by its redox active subdomain, which carries the covalently bound heme. It, therefore, seems that this domain interacts differently with distinct redox partners, like the photochemical reaction center and the Cytcoxidase, and allows the bacteria to funnel electrons efficiently to various destinations under different growth conditions. These findings raise an intriguing evolutionary issue in regard to cellular apoptosis: why do the mitochondria of higher organisms, unlike their bacterial ancestors, use only one soluble electron carrier in their respiratory electron-transport chains?