Laboratory of Plant Biotechnology, Faculty of Sciences, University of Sfax, BP 1171, 3000 Sfax, Tunisia; Laboratoire de Génie Civil et géo-Environnement, Université de Lille 1, F-59655 Villeneuve d'Ascq, France.
Laboratory of Plant Biotechnology, Faculty of Sciences, University of Sfax, BP 1171, 3000 Sfax, Tunisia.
Ecotoxicol Environ Saf. 2017 Jun;140:7-17. doi: 10.1016/j.ecoenv.2017.02.020. Epub 2017 Feb 27.
We studied date palm phytochelatin synthase type I (PdPCS1), which catalyzes the cytosolic synthesis of phytochelatins (PCs), a heavy metal binding protein, in plant cells. The gene encoding PdPCS1 (Pdpcs) consists of 8 exons and 7 introns and encodes a protein of 528 amino acids. PCs gene history was studied using Notung phylogeny. During evolution, gene loss from several lineages was predicted including Proteobacteria, Bilateria and Brassicaceae. In addition, eleven gene duplication events appeared toward interior nodes of the reconciled tree and four gene duplication events appeared toward the external nodes. These latter sequences belong to species with a second copy of PCs suggesting that this gene evolved through subfunctionalization. Pdpcs1 gene expression was measured in seedling hypocotyls exposed to Cd, Cu and Cr using quantitative real-time polymerase chain reaction (qPCR). A Pdpcs1 overexpression was evidenced in P. dactylifera seedlings exposed to metals suggesting that 1-the Pdpcs1 gene is functional, 2-there is an implication of the enzyme in metal detoxification mechanisms. Additionally, the structure of PdPCS1 was predicted using its homologue from Nostoc (cyanobacterium, NsPCS) as a template in Discovery studio and PyMol software. These analyses allowed us to identify the phytochelatin synthase type I enzyme in date palm (PdPCS1) via recognition of key consensus amino acids involved in the catalytic mechanism, and to propose a hypothetical binding and catalytic site for an additional substrate binding cavity.
我们研究了棕榈植物的植物螯合肽合酶 I 型（PdPCS1），它在植物细胞中催化植物螯合肽（PCs）的细胞质合成，PCs 是一种重金属结合蛋白。编码 PdPCS1（Pdpcs）的基因由 8 个外显子和 7 个内含子组成，编码 528 个氨基酸的蛋白质。使用 Notung 系统发生法研究了 PCs 基因的历史。在进化过程中，预测了几个谱系的基因丢失，包括变形菌门、两侧对称动物和十字花科。此外，在调和树的内部节点出现了十一个基因复制事件，在外部节点出现了四个基因复制事件。这些后一个序列属于具有第二个 PC 副本的物种，表明该基因通过亚功能化进化。使用定量实时聚合酶链反应（qPCR）测量幼苗下胚轴暴露于 Cd、Cu 和 Cr 时 Pdpcs1 基因的表达。在暴露于金属的 P. dactylifera 幼苗中证实了 Pdpcs1 的过表达，表明 1-Pdpcs1 基因是功能性的，2-该酶参与了金属解毒机制。此外，还使用来自 Nostoc（蓝藻，NsPCS）的同源物作为模板在 Discovery studio 和 PyMol 软件中预测了 PdPCS1 的结构。这些分析使我们能够通过识别参与催化机制的关键保守氨基酸来识别棕榈植物中的植物螯合肽合酶 I 型（PdPCS1），并为额外的底物结合腔提出了一个假设的结合和催化位点。
