NDF6: A thylakoid protein specific to terrestrial plants is essential for activity of chloroplastic NAD(P)H dehydrogenase in arabidopsis
NDF6: A thylakoid protein specific to terrestrial plants is essential for activity of chloroplastic NAD(P)H dehydrogenase in arabidopsis
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DOI：
10.1093/pcp/pcn083
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发表时间：
2008-07-01
影响因子：
4.9
通讯作者：
Sato, Fumihiko
中科院分区：
文献类型：
--
作者：
Ishikawa, Noriko;Takabayashi, Atsushi;Sato, Fumihiko
NAD(P)H脱氢酶(NDH)是呼吸复合体I的同系物，介导了PSI(CEF I)的两条循环电子流动途径之一。虽然已经在高等植物的叶绿体和核基因组中鉴定出15个NDH亚基，但到目前为止还没有鉴定出电子受体亚基。为了确定缺失的叶绿体NDH亚基，我们采用了基于共表达分析的电子计算机方法。在这份报告中，我们鉴定了新基因NDF6(NDH依赖的Flow 6；At1g18730)，它编码一种对NDH活性至关重要的蛋白质。NDF6有一个跨膜结构域，定位于类囊体膜组分。在陆生植物基因组中发现了NDF6的同源蛋白，但在蓝藻中没有发现同源蛋白，蓝藻被认为是叶绿体的起源，具有最小的NDH复合体单位。NDF6在NDHB受损或破坏的高等植物突变体中是不稳定的，在这些突变体中，叶绿体NDH复合体被认为是降解的。这些结果表明，NDF6是一个新的氯化NDH亚基，在进化过程中被添加到陆地植物中。
NAD(P)H dehydrogenase (NDH) is a homolog of respiratory complex I and mediates one of the two pathways of cyclic electron flow around PSI (CEF I). Although 15 ndh subunits have been identified in the chloroplastic and nuclear genomes of higher plants, no electron accepter subunits have been identified to date. To identify the missing chloroplastic NDH subunits, we undertook an in silico approach based on co-expression analysis. In this report, we characterized the novel gene NDF6 (NDH-dependent flow 6; At1g18730) which encodes a protein that is essential for NDH activity. NDF6 has one transmembrane domain and is localized in the thylakoid membrane fraction. Homologous proteins of NDF6 were identified in the genomes of terrestrial plants; however, no homologs have been found in cyanobacteria, which are thought to be the origin of chloroplasts and have a minimal NDH complex unit. NDF6 is unstable in ndhB-impaired or disrupted mutants of higher plants in which the chloroplastic NDH complex is thought to be degraded. These results suggest that NDF6 is a novel subunit of chloroplastic NDH that was added to terrestrial plants during evolution.