PIC1, an ancient permease in Arabidopsis chloroplasts, mediates iron transport
PIC1, an ancient permease in Arabidopsis chloroplasts, mediates iron transport
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DOI：
10.1105/tpc.106.047407
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发表时间：
2007-03-01
期刊：
影响因子：
11.6
通讯作者：
Philippar, Katrin
中科院分区：
文献类型：
--
作者：
Duy, Daniela;Wanner, Gerhard;Philippar, Katrin
在叶绿体中，过渡金属铁和铜在光合电子传递中起重要作用，并作为超氧化物歧化酶的辅因子。铁是叶绿素生物合成所必需的，质体中的铁蛋白簇在萌发、发育和铁胁迫期间储存铁。因此，过渡金属，特别是铁的质体内稳态对于叶绿体以及植物发育至关重要。然而，很少有人知道铁吸收叶绿体。拟南芥叶绿体渗透酶1（PIC 1），在质体中的金属转运蛋白筛选中鉴定，含有四个预测的α-螺旋，靶向内包膜，并显示与蓝藻渗透酶样蛋白的同源性。PIC 1的敲除突变体只生长异养，其特征在于由缺铁植物的褪绿和矮化表型。质体的超微结构分析显示，严重受损的叶绿体发育和铁蛋白簇显着增加。除了上调铁蛋白，pic 1突变体表现出差异调节的基因和蛋白质相关的铁胁迫或运输，光合作用，和Fe-S集群生物合成。此外，PIC 1和它的蓝藻同系物介导的铁积累在铁摄取缺陷的酵母突变体。这些观察结果表明，PIC 1的功能在铁运输通过叶绿体的内被膜，因此在细胞的金属稳态。
In chloroplasts, the transition metals iron and copper play an essential role in photosynthetic electron transport and act as cofactors for superoxide dismutases. Iron is essential for chlorophyll biosynthesis, and ferritin clusters in plastids store iron during germination, development, and iron stress. Thus, plastidic homeostasis of transition metals, in particular of iron, is crucial for chloroplast as well as plant development. However, very little is known about iron uptake by chloroplasts. Arabidopsis thaliana PERMEASE IN CHLOROPLASTS1 (PIC1), identified in a screen for metal transporters in plastids, contains four predicted alpha-helices, is targeted to the inner envelope, and displays homology with cyanobacterial permease-like proteins. Knockout mutants of PIC1 grew only heterotrophically and were characterized by a chlorotic and dwarfish phenotype reminiscent of iron-deficient plants. Ultrastructural analysis of plastids revealed severely impaired chloroplast development and a striking increase in ferritin clusters. Besides upregulation of ferritin, pic1 mutants showed differential regulation of genes and proteins related to iron stress or transport, photosynthesis, and Fe-S cluster biogenesis. Furthermore, PIC1 and its cyanobacterial homolog mediated iron accumulation in an iron uptake-defective yeast mutant. These observations suggest that PIC1 functions in iron transport across the inner envelope of chloroplasts and hence in cellular metal homeostasis.