John Warren A, Lückel Benita, Matschiavelli Nicole, Hübner René, Matschi Susanne, Hoehenwarter Wolfgang, Sachs Susanne
Helmholtz - Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany.
Helmholtz - Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden, Germany.
Sci Total Environ. 2022 Jun 1;823:153700. doi: 10.1016/j.scitotenv.2022.153700. Epub 2022 Feb 7.
Endocytosis of metals in plants is a growing field of study involving metal uptake from the rhizosphere. Uranium, which is naturally and artificially released into the rhizosphere, is known to be taken up by certain species of plant, such as Nicotiana tabacum, and we hypothesize that endocytosis contributes to the uptake of uranium in tobacco. The endocytic uptake of uranium was investigated in tobacco BY-2 cells using an optimized setup of culture in phosphate-deficient medium. A combination of methods in biochemistry, microscopy and spectroscopy, supplemented by proteomics, were used to study the interaction of uranium and the plant cell. We found that under environmentally relevant uranium concentrations, endocytosis remained active and contributed to 14% of the total uranium bioassociation. Proteomics analyses revealed that uranium induced a change in expression of the clathrin heavy chain variant, signifying a shift in the type of endocytosis taking place. However, the rate of endocytosis remained largely unaltered. Electron microscopy and energy-dispersive X-ray spectroscopy showed an adsorption of uranium to cell surfaces and deposition in vacuoles. Our results demonstrate that endocytosis constitutes a considerable proportion of uranium uptake in BY-2 cells, and that endocytosed uranium is likely targeted to the vacuole for sequestration, providing a physiologically safer route for the plant than uranium transported through the cytosol.
植物中金属的内吞作用是一个不断发展的研究领域，涉及从根际吸收金属。铀会自然和人为地释放到根际，已知某些植物物种，如烟草，会吸收铀，我们推测内吞作用有助于烟草吸收铀。我们使用在缺磷培养基中优化的培养设置，研究了烟草BY-2细胞中铀的内吞摄取。采用生物化学、显微镜和光谱学相结合的方法，并辅以蛋白质组学，来研究铀与植物细胞的相互作用。我们发现，在与环境相关的铀浓度下，内吞作用仍然活跃，占总铀生物结合量的14%。蛋白质组学分析表明，铀诱导了网格蛋白重链变体表达的变化，这表明发生的内吞作用类型发生了转变。然而，内吞作用的速率基本保持不变。电子显微镜和能量色散X射线光谱显示铀吸附在细胞表面并沉积在液泡中。我们的结果表明，内吞作用在BY-2细胞吸收铀的过程中占相当大的比例，并且内吞的铀可能靶向液泡进行隔离，这为植物提供了一条比通过细胞质运输铀生理上更安全的途径。
