Department of Biology and Ecology, Faculty of Sciences, University of Novi Sad, Novi Sad, Serbia.
Institute for Biological Research "Siniša Stanković", University of Belgrade, Belgrade, Serbia.
Mol Ecol. 2019 Feb;28(4):731-745. doi: 10.1111/mec.14984.
Metallothioneins are ubiquitous proteins important in metal homeostasis and detoxification. However, they have not previously been identified in honey bees or other Hymenoptera, where metallothioneins could be of ecophysiological and ecotoxicological significance. Better understanding of the molecular responses to stress induced by toxic metals could contribute to honey bee conservation. In addition, honey bee metallothionein could represent a biomarker for monitoring environmental quality. Here we identify and characterize a metallothionein gene in Apis mellifera (AmMT). AmMT is 1,680 bp long and encodes a 48 amino acids protein with 15 cysteines and no aromatic residues. A metal response element upstream of the start codon, coupled with numerous cis-regulatory elements indicate the functional context of AmMT. Molecular modelling predicts several transition metal binding sites, and comparative phylogenetic analysis revealed five putative metallothionein proteins in three other hymenoptera species. AmMT was characterized by cloning the full-length coding sequence of the putative metallothionein. Recombinant AmMT was found to increase metal tolerance upon overexpression in Escherichia coli supplemented with Cd, Cu or Pb. Finally, in laboratory tests on honey bees, gene expression profiles showed a dose-dependant relationship between Cd, Cu and Pb concentrations present in food and AmMT expression, while field experiments showed induction of AmMT in bees from an industrial site compared to those from an urban area. These studies suggest that AmMT has metal binding properties in agreement with a possible role in metal homeostasis. Further functional and structural characterization of metallothionein in honey bees and other Hymenoptera are necessary.
金属硫蛋白是一类在金属稳态和解毒中起重要作用的普遍存在的蛋白质。然而，它们以前从未在蜜蜂或其他膜翅目昆虫中被发现过，而金属硫蛋白在这些昆虫中可能具有生态生理学和生态毒理学意义。更好地了解有毒金属诱导的应激的分子反应可能有助于保护蜜蜂。此外，蜜蜂金属硫蛋白可以作为监测环境质量的生物标志物。在这里，我们鉴定并描述了蜜蜂（Apis mellifera）中的一个金属硫蛋白基因（AmMT）。AmMT 长 1680bp，编码一个 48 个氨基酸的蛋白质，有 15 个半胱氨酸和没有芳香族残基。起始密码子上游的金属反应元件，加上许多顺式调控元件，表明了 AmMT 的功能背景。分子建模预测了几个过渡金属结合位点，比较系统发育分析显示在其他三种膜翅目昆虫中有五个假定的金属硫蛋白蛋白。通过克隆假定的金属硫蛋白的全长编码序列来鉴定 AmMT。发现重组 AmMT 在大肠杆菌中过表达时，在添加 Cd、Cu 或 Pb 的情况下增加了金属耐受性。最后，在对蜜蜂的实验室测试中，基因表达谱显示在食物中存在 Cd、Cu 和 Pb 浓度与 AmMT 表达之间存在剂量依赖性关系，而田间实验表明，与来自城市地区的蜜蜂相比，来自工业场所的蜜蜂中的 AmMT 被诱导。这些研究表明，AmMT 具有金属结合特性，这与它在金属稳态中的可能作用一致。需要进一步对蜜蜂和其他膜翅目昆虫中的金属硫蛋白进行功能和结构表征。
