Rice-Specific Mitochondrial Iron-Regulated Gene (MIR) Plays an Important Role in Iron Homeostasis
Rice-Specific Mitochondrial Iron-Regulated Gene (MIR) Plays an Important Role in Iron Homeostasis
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DOI：
10.1093/mp/ssp051
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发表时间：
2009-09-01
期刊：
影响因子：
27.5
通讯作者：
Nishizawa, Naoko K.
中科院分区：
文献类型：
--
作者：
Ishimaru, Yasuhiro;Bashir, Khurram;Nishizawa, Naoko K.
线粒体利用铁(Fe)，但参与线粒体铁调节的蛋白质在植物中并不是特有的。我们克隆并鉴定了水稻线粒体铁调节(MIR)基因，该基因参与铁的动态平衡。MIR在烟草BY-2细胞中表达时，定位于线粒体。根和地上部组织中的MIR转录本在缺铁条件下显著增加。MIR与任何已知的蛋白质都不是同源的，因为在水稻或拟南芥基因组数据库中没有发现同源蛋白，或者在其他生物的EST数据库中没有发现同源蛋白。与野生型水稻(WT)相比，在缺铁或缺铁条件下，MIR T-DNA基因敲除水稻突变体(Mir)的生长明显受损。此外，无论在缺铁或富铁条件下，MIR植株在地上部和根组织中的铁积累量都是WT植株的两倍以上。尽管铁在根和地上部的积累很高，但mir植物触发了缺铁诱导基因的表达，这表明mir可能不能利用Fe来实现生理功能。这些结果清楚地表明，MIR是一种水稻特有的线粒体蛋白，最近进化而来，在铁稳态中发挥着重要作用。
Mitochondria utilize iron (Fe), but the proteins involved in mitochondrial Fe regulation are not characterized in plants. We cloned and characterized a mitochondrial iron-regulated (MIR) gene in rice involved in Fe homeostasis. MIR, when expressed in tobacco BY-2 cells, was localized to the mitochondria. MIR transcripts were greatly increased in response to Fe deficiency in roots and shoot tissue. MIR is not homologous to any known protein, as homologs were not found in the rice or Arabidopsis genome databases, or in the EST database for other organisms. Growth in the MIR T-DNA knockout rice mutant (mir) was significantly impaired compared to wild-type (WT) plants when grown under Fe-deficient or -sufficient conditions. Furthermore, mir plants accumulated more than twice the amount of Fe in shoot and root tissue compared to WT plants when grown under either Fe-sufficient or -deficient conditions. Despite the high accumulation of Fe in roots and shoots, mir plants triggered the expression of Fe-deficiency-inducible genes, indicating that mir may not be able to utilize Fe for physiological functions. These results clearly suggest that MIR is a rice-specific mitochondrial protein, recently evolved, and plays a significant role in Fe homeostasis.