IRT1 DEGRADATION FACTOR1, a RING E3 Ubiquitin Ligase, Regulates the Degradation of IRON-REGULATED TRANSPORTER1 in Arabidopsis
IRT1 DEGRADATION FACTOR1, a RING E3 Ubiquitin Ligase, Regulates the Degradation of IRON-REGULATED TRANSPORTER1 in Arabidopsis
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DOI：
10.1105/tpc.113.115212
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发表时间：
2013-08-01
期刊：
影响因子：
11.6
通讯作者：
Yeh, Kuo-Chen
中科院分区：
文献类型：
--
作者：
Shin, Lung-Jiun;Lo, Jing-Chi;Yeh, Kuo-Chen
铁是植物生长和发育所必需的微量营养素;植物已经发展出复杂的策略来从土壤中获取铁。非禾本科植物通过基于还原的机制获得Fe，禾本科植物使用基于螯合的机制。在使用还原法的拟南芥中，铁调节转运蛋白1（IRON-REGULATED TRANSPORTER 1，IRT 1）是亚铁吸收的最重要的转运蛋白。IRT 1的快速组成性降解使植物能够快速响应变化的条件，以维持铁的稳态。IRT 1降解涉及泛素化。为了鉴定参与IRT 1降解的特异性E3泛素连接酶，我们筛选了一组RING型E3连接酶的插入突变体，并鉴定了一种显示IRT 1延迟降解和IRT 1-泛素复合物丢失的突变体。相应的基因被命名为IRT 1降解因子1（IDF 1）。IDF 1和IRT 1在质膜中直接相互作用的证据支持IDF 1在IRT 1降解中的作用。IRT 1的积累减少时，共表达与酵母或非洲爪蟾卵母细胞中的IDF 1。IDF 1的功能依赖于RING结构域。idf 1突变体表现出增加耐受铁缺乏，导致增加IRT 1水平。这一证据表明，IDF 1通过其RING型E3连接酶活性直接调节IRT 1降解。
Fe is an essential micronutrient for plant growth and development; plants have developed sophisticated strategies to acquire ferric Fe from the soil. Nongraminaceous plants acquire Fe by a reduction-based mechanism, and graminaceous plants use a chelation-based mechanism. In Arabidopsis thaliana, which uses the reduction-based method, IRON-REGULATED TRANSPORTER1 (IRT1) functions as the most important transporter for ferrous Fe uptake. Rapid and constitutive degradation of IRT1 allows plants to quickly respond to changing conditions to maintain Fe homeostasis. IRT1 degradation involves ubiquitination. To identify the specific E3 ubiquitin ligases involved in IRT1 degradation, we screened a set of insertional mutants in RING-type E3 ligases and identified a mutant that showed delayed degradation of IRT1 and loss of IRT1-ubiquitin complexes. The corresponding gene was designated IRT1 DEGRADATION FACTOR1 (IDF1). Evidence of direct interaction between IDF1 and IRT1 in the plasma membrane supported the role of IDF1 in IRT1 degradation. IRT1 accumulation was reduced when coexpressed with IDF1 in yeast or Xenopus laevis oocytes. IDF1 function was RING domain dependent. The idf1 mutants showed increased tolerance to Fe deficiency, resulting from increased IRT1 levels. This evidence indicates that IDF1 directly regulates IRT1 degradation through its RING-type E3 ligase activity.