Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, Poznań, Poland.
Mol Biol Evol. 2010 Jan;27(1):91-101. doi: 10.1093/molbev/msp196.
Ferritins are one of the most important elements of cellular machinery involved in iron management. Despite extensive studies conducted during the last decade, many factors regulating the expression of ferritin genes in plants remain unknown. To broaden our knowledge about the mechanisms controlling ferritin production in plant cells, we have identified and characterized a new family of ferritin genes (from yellow lupine). We have also inventoried all available plant ferritins and their genes and subjected them to a complex bioinformatic analysis. It showed that the conservative structure of ferritin genes was established much earlier than it was thought before. The first introns in ferritin genes appeared already in green algae. The number and location of introns have been finally established in mosses, over 400 million years ago, and are strictly preserved in all plants from bryophytes to dicots. Comparison of ferritin gene promoters revealed that the 14-bp-long iron-dependent regulatory sequence (IDRS), identified earlier in Arabidopsis and maize, is characteristic for all higher plants. Moreover, we found that a highly conserved IDRS can be extended (extIDRS) up to 22 bp. Phylogenetic analysis of plant ferritins showed that polypeptides of the eudicot clade can be divided into two subclasses (eudicot-1 and eudicot-2). Interestingly, we found that genes encoding proteins classified as eudicot-1 and eudicot-2 are equipped with class-specific promoters. This suggests that eudicot ferritins are structurally and perhaps functionally diverse. Based on the above observations, we were able to identify conservative elements (ELEM1--6) other than extIDRS within plant ferritin gene promoters. We also found E-boxes and iron-responsive sequence elements FeRE1 and 2, characteristically distributed within ferritin promoters. Because most of the identified conserved sequences are located within or in close proximity of extIDRS, we named this fragment of the plant ferritin gene promoter the regulatory element rich region.
铁蛋白是参与铁管理的细胞机制中最重要的元素之一。尽管在过去的十年中进行了广泛的研究，但许多调节植物铁蛋白基因表达的因素仍然未知。为了扩大我们对控制植物细胞中铁蛋白产生的机制的了解，我们已经鉴定和表征了一个新的铁蛋白基因家族（来自黄羽扇豆）。我们还对所有可用的植物铁蛋白及其基因进行了编目，并对它们进行了复杂的生物信息学分析。结果表明，铁蛋白基因的保守结构的建立时间远比以前认为的要早。铁蛋白基因中的第一个内含子早在绿藻中就出现了。大约 4 亿年前，在苔藓植物中最终确定了内含子的数量和位置，并且在从苔藓植物到双子叶植物的所有植物中都严格保留了这些内含子。铁蛋白基因启动子的比较表明，早些时候在拟南芥和玉米中鉴定出的 14 个碱基对长的铁依赖性调节序列（IDRS）是所有高等植物的特征。此外，我们发现一个高度保守的 IDRS 可以延长（extIDRS）到 22 个碱基对。植物铁蛋白的系统发育分析表明，真双子叶植物的多肽可以分为两个亚类（eudicot-1 和 eudicot-2）。有趣的是，我们发现编码被归类为 eudicot-1 和 eudicot-2 的蛋白质的基因配备了具有特定类别的启动子。这表明真双子叶植物铁蛋白在结构上可能具有多样性。基于上述观察结果，我们能够在植物铁蛋白基因启动子中识别出除 extIDRS 之外的保守元件（ELEM1--6）。我们还发现了 E 盒和铁反应序列元件 FeRE1 和 2，它们在铁蛋白启动子中特征性分布。由于大多数鉴定出的保守序列位于 extIDRS 内部或附近，因此我们将植物铁蛋白基因启动子的这个片段命名为富含调节元件的区域。
