Palusińska Małgorzata, Barabasz Anna, Antosiewicz Danuta Maria
U niversity of Warsaw, Faculty of Biology, Institute of Experimental Plant Biology and Biotechnology, 1 Miecznikowa Str.,02-096 Warszawa, Poland.
Department of Molecular Biology, Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Postępu 36A, 05-552 Magdalenka, Poland.
Metallomics. 2024 Sep 5;16(9). doi: 10.1093/mtomcs/mfae035.
Plants grow in soils with varying concentrations of microelements, often in the presence of toxic metals e.g. Cd. To cope, they developed molecular mechanisms to regulate metal cross-homeostasis. Understanding underlying complex relationships is key to improving crop productivity. Recent research suggests that the Zn and Cd uptake protein NtZIP5A/B [Zinc-regulated, Iron-regulated transporter-like Proteins (ZIPs)] from tobacco (Nicotiana tabacum L. v. Xanthi) is involved in the regulation of a cross-talk between the two metals. Here, we support this conclusion by showing that RNAi-mediated silencing of NtZIP5A/B resulted in a reduction of Zn accumulation and that this effect was significantly enhanced by the presence of Cd. Our data also point to involvement of NtZIP5B in regulating a cross-talk between Cu, Fe, and Mn. Using yeast growth assays, Cu (but not Fe or Mn) was identified as a substrate for NtZIP5B. Furthermore, GUS-based analysis showed that the tissue-specific activity of the NtZIP5B promoter was different in each of the Zn-/Cu-/Fe-/Mn deficiencies applied with/without Cd. The results indicate that NtZIP5B is involved in maintaining multi-metal homeostasis under conditions of Zn, Cu, Fe, and Mn deficiency, and also in the presence of Cd. It was concluded that the protein regulates the delivery of Zn and Cu specifically to targeted different root cells depending on the Zn/Cu/Fe/Mn status. Importantly, in the presence of Cd, the activity of the NtZIP5B promoter is lost in meristematic cells and increased in mature root cortex cells, which can be considered a manifestation of a defense mechanism against its toxic effects.
植物生长在微量元素浓度各异的土壤中，且常常存在有毒金属，如镉。为了应对这种情况，它们发展出分子机制来调节金属的交叉稳态。理解其中潜在的复杂关系是提高作物产量的关键。最近的研究表明，来自烟草（Nicotiana tabacum L. v. Xanthi）的锌和镉吸收蛋白NtZIP5A/B [锌调节、铁调节转运蛋白样蛋白（ZIPs）]参与了这两种金属之间的相互作用调节。在此，我们通过表明RNAi介导的NtZIP5A/B沉默导致锌积累减少，且镉的存在显著增强了这种效应，来支持这一结论。我们的数据还表明NtZIP5B参与调节铜、铁和锰之间的相互作用。通过酵母生长试验，确定铜（而非铁或锰）是NtZIP5B的底物。此外，基于GUS的分析表明，在添加/不添加镉的情况下，应用锌/铜/铁/锰缺乏处理时，NtZIP5B启动子的组织特异性活性各不相同。结果表明，NtZIP5B在锌、铜、铁和锰缺乏条件下以及存在镉的情况下都参与维持多金属稳态。得出的结论是，该蛋白根据锌/铜/铁/锰的状态，将锌和铜特异性地输送到不同的目标根细胞。重要的是，在存在镉的情况下，NtZIP5B启动子的活性在分生细胞中丧失，而在成熟根皮层细胞中增加，这可被视为对其毒性作用的防御机制的一种表现。
