Ferritins and iron accumulation in plant tissues
Ferritins and iron accumulation in plant tissues
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DOI：
10.1007/1-4020-4743-6_17
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发表时间：
2006-01-01
期刊：
影响因子：
--
通讯作者：
Gaymard, Frederic
中科院分区：
文献类型：
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作者：
Briat, Jean-Francois;Cellier, Francoise;Gaymard, Frederic
在生理pH下，铁倾向于以不溶性形式沉淀。此外，其氧化还原循环通过芬顿化学参与还原形式的氧的活化，导致细胞损伤和细胞死亡。由于这些特性，植物已经进化出控制铁吸收和储存的机制。一类多聚体蛋白，铁蛋白，通过以可溶的、无毒的和生物可利用的形式储存这种离子，在细胞内充当铁缓冲剂。这些蛋白质存在于植物、动物、真菌和细菌中。在植物中，它们定位于质体内，并且它们的合成受发育和环境因素（如铁过量或氧化应激）的调节。特别是，铁超载转录激活一些铁蛋白基因。脱落酸依赖性和脱落酸非依赖性途径都参与了这种铁反应。后者涉及一些磷酸化和去磷酸化事件，并且在一些铁蛋白启动子序列中已经证明了特定的顺式调节元件。铁蛋白的表达已经通过在各种异源启动子的控制下过表达而在转基因植物中被实验性地解除调节。由于这些转基因植物中铁蛋白的积累，随着根系铁还原酶和根系H+-ATP酶活性的增加而增加，这两个决定双子叶植物铁吸收的关键因素。这导致提出一种生物技术方法来治疗估计影响世界人口30%的人类缺铁症。然而，植物铁蛋白过度积累的富铁表型似乎是高度依赖于土壤类型。
At physiological pH, iron tends to precipitate as insoluble forms. Furthermore, its redox cycling participates in activation of reduced forms of oxygen through Fenton chemistry, leading to cellular damage and cell death. As a consequence of these properties, plants have evolved mechanisms to control iron uptake and storage. A class of multimeric proteins, the ferritins, acts as an iron buffer inside the cell by storing this ion in a soluble, non-toxic and bioavailable form. These proteins are present in plants, animals, fungi and bacteria. In plants, they are localized within plastids, and their synthesis is regulated by developmental and environmental factors, such as iron excess or oxidative stress. In particular, iron overload transcriptionally activates some ferritin genes. Both an abscissic acid-dependent and an abscissic acid-independent pathway are involved in this iron response. The latter involves some phosphorylation and dephosphorylation events, and specific cis-regulatory elements have been evidenced in some ferritin promoter sequences. Ferritin expression has been experimentally deregulated in transgenic plants by overexpressing them under the control of various heterologous promoters. As a consequence of ferritin accumulation in these transgenic plants, an increase with an increase in root ferric reductase and root H+-ATPase activities, two key determinants of iron uptake by dicotyledonous plants. This leads to propose a biotechnological approach to treat human iron deficiency estimated to affect 30% of the world population. However, the iron–enriched phenotype of plants over-accumulating ferritins seems to be highly soil-type dependent.