A FIT-binding protein is involved in modulating iron and zinc homeostasis in Arabidopsis
A FIT-binding protein is involved in modulating iron and zinc homeostasis in Arabidopsis
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DOI：
10.1111/pce.13321
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发表时间：
2018-07-01
影响因子：
7.3
通讯作者：
Ling, Hong-Qing
中科院分区：
文献类型：
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作者：
Chen, Chun-Lin;Cui, Yan;Ling, Hong-Qing
铁和锌是植物生长必需的微量元素，它们之间的动态平衡关系非常复杂。在这项研究中，我们利用酵母双杂交系统鉴定了一个fitt结合蛋白（FBP）。FBP的c端与FIT的bHLH结构域结合，使FIT的dna结合能力丧失。敲除FBP导致NAS基因表达增强和烟胺含量增加，FBP突变体对过量Zn表现出耐受性。生理分析表明，在锌过量胁迫下，突变体fbp比野生型在根中保留了更多的锌，并将更多的铁转移到芽中。由于FBP在根茎中表达，因此由FIT的隔离引起的负调控仅限于该组织，而其他主要表达于根表皮的FIT调控基因，如IRT1和FRO2，在FBP突变体中没有表现出转录上调。作为拮抗伙伴，FBP提供了一种空间微调FIT控制基因表达的新方法。综上所述，我们的研究结果为了解植物铁和锌动态平衡的相互关系提供了新的视角。
Fe and Zn are essential micronutrients for plant growth, and the interrelationship regarding their homeostasis is very complicated. In this study, we identified a FIT-binding protein (FBP) using the yeast two-hybrid system. The C-terminus of FBP binds to the bHLH domain of FIT, abolishing the DNA-binding capacity of FIT. Knockout of FBP results in an enhanced expression of NAS genes and a higher nicotianamine content, and the fbp mutant exhibits tolerance to excessive Zn. Physiological analyses reveal that the mutant fbp retains a larger amount of Zn in roots and transfers a greater proportion of Fe to shoots than that in wild type under Zn-excessive stress. As FBP is expressed in the root stele, the negative regulation caused by sequestration of FIT is restricted to this tissue, whereas other FIT-regulated genes, such as IRT1 and FRO2, which mainly expressed in root epidermis, do not show transcriptional upregulation in the fbp mutant. As an antagonistic partner, FBP offers a new approach to spatially fine-tune the expression of genes controlled by FIT. In conclusion, our findings provide a new insight to understand the interrelationship of Fe and Zn homeostasis in plants.