Ivanov Rumen, Brumbarova Tzvetina, Blum Ailisa, Jantke Anna-Maria, Fink-Straube Claudia, Bauer Petra
Institute of Botany, Heinrich-Heine University, D-40225 Duesseldorf, Germany.
Plant Cell. 2014 Mar;26(3):1294-307. doi: 10.1105/tpc.113.116244. Epub 2014 Mar 4.
Dicotyledonous plants growing under limited iron availability initiate a response resulting in the solubilization, reduction, and uptake of soil iron. The protein factors responsible for these steps are transmembrane proteins, suggesting that the intracellular trafficking machinery may be involved in iron acquisition. In search for components involved in the regulation of Arabidopsis thaliana iron deficiency responses, we identified the members of the SORTING NEXIN (SNX) protein family. SNX loss-of-function plants display enhanced susceptibility to iron deficiency in comparison to the wild type. The absence of SNX led to reduced iron import efficiency into the root. SNX1 showed partial colocalization with the principal root iron importer IRON-REGULATED TRANSPORTER1 (IRT1). In SNX loss-of-function plants, IRT1 protein levels were decreased compared with the wild type due to enhanced IRT1 degradation. This resulted in diminished amounts of the IRT1 protein at the plasma membrane. snx mutants exhibited enhanced iron deficiency responses compared with the wild type, presumably due to the lower iron uptake through IRT1. Our results reveal a role of SNX1 for the correct trafficking of IRT1 and, thus, for modulating the activity of the iron uptake machinery.
在铁供应有限的条件下生长的双子叶植物会启动一种反应，导致土壤中铁的溶解、还原和吸收。负责这些步骤的蛋白质因子是跨膜蛋白，这表明细胞内运输机制可能参与铁的获取。为了寻找参与拟南芥缺铁反应调控的成分，我们鉴定了分选连接蛋白（SNX）蛋白家族的成员。与野生型相比，SNX功能缺失的植物对缺铁表现出更高的敏感性。SNX的缺失导致铁进入根部的效率降低。SNX1与主根铁转运蛋白铁调节转运蛋白1（IRT1）部分共定位。在SNX功能缺失的植物中，由于IRT1降解增强，IRT1蛋白水平与野生型相比降低。这导致质膜上IRT1蛋白的量减少。与野生型相比，snx突变体表现出增强的缺铁反应，可能是由于通过IRT1的铁吸收较低。我们的结果揭示了SNX1在IRT1正确运输中的作用，从而在调节铁吸收机制的活性方面发挥作用。
