Posttranslational Regulation of the Iron Deficiency Basic Helix-Loop-Helix Transcription Factor FIT Is Affected by Iron and Nitric Oxide
Posttranslational Regulation of the Iron Deficiency Basic Helix-Loop-Helix Transcription Factor FIT Is Affected by Iron and Nitric Oxide
复制标题
DOI：
10.1104/pp.111.183285
复制
发表时间：
2011-12-01
期刊：
影响因子：
7.4
通讯作者：
Bauer, Petra
中科院分区：
文献类型：
--
作者：
Meiser, Johannes;Lingam, Sivasenkar;Bauer, Petra
了解铁 (Fe) 传感和调节对于针对铁含量等重要营养性状的关键基因非常重要。基本的螺旋-环-螺旋转录因子 FIT（FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR）控制双子叶植物根中的 Fe 获取基因。转录因子的转录后调节可以快速适应细胞变化，FIT 也对此进行了描述。然而，长期以来，FIT 监管背后的机制尚不清楚。在这里，我们研究了拟南芥 (Arabidopsis thaliana) 中 FIT 的转录后控制机制，并确定一氧化氮是 FIT 蛋白丰度的稳定刺激物。使用放线菌酮，我们证实野生型和血凝素 FIT 植物中 FIT 蛋白的水平是通过蛋白质周转的方式调节的。放线菌酮处理后，FIT 活性几乎没有受到影响，因为缺铁基因（如铁调节转运蛋白 1 和铁还原酶氧化酶 2）仍然可由缺铁诱导。一小部分“活性”FIT 足以诱导缺铁下游反应。一氧化氮抑制剂会导致 FIT 蛋白丰度下降，并且在野生型中，也会导致 FIT 活性下降。 FIT 蛋白水平的降低可被蛋白酶体抑制剂 MG132 逆转，这表明在一氧化氮存在的情况下，FIT 蛋白不太可能成为蛋白酶体降解的目标。因此，独立于 FIT 转录，FIT 蛋白稳定性和 FIT 蛋白活性是响应 Fe 和一氧化氮的控制机制的目标。我们在一个模型中总结了我们的结果，该模型解释了集成控制 FIT 的植物信号的 FIT 调节的不同步骤。
Understanding iron (Fe) sensing and regulation is important for targeting key genes for important nutritional traits like Fe content. The basic helix-loop-helix transcription factor FIT (for FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR) controls Fe acquisition genes in dicot roots. Posttranscriptional regulation of transcription factors allows rapid adaptation to cellular changes and was also described for FIT. However, the mechanisms behind this regulation of FIT were for a long time not known. Here, we studied the posttranscriptional control mechanisms of FIT in Arabidopsis (Arabidopsis thaliana) and identified nitric oxide as a stabilizing stimulus for FIT protein abundance. Using cycloheximide, we confirmed that the level of FIT protein was regulated by way of protein turnover in wild-type and hemagglutinin-FIT plants. Upon cycloheximide treatment, FIT activity was hardly compromised, since Fe deficiency genes like IRON-REGULATED TRANSPORTER1 and FERRIC REDUCTASE OXIDASE2 were still inducible by Fe deficiency. A small pool of "active" FIT was sufficient for the induction of Fe deficiency downstream responses. Nitric oxide inhibitors caused a decrease of FIT protein abundance and, in the wild type, also a decrease in FIT activity. This decrease of FIT protein levels was reversed by the proteasomal inhibitor MG132, suggesting that in the presence of nitric oxide FIT protein was less likely to be a target of proteasomal degradation. Independent of FIT transcription, FIT protein stability and FIT protein activity, therefore, were targets of control mechanisms in response to Fe and nitric oxide. We summarize our results in a model that explains the different steps of FIT regulation integrating the plant signals that control FIT.