苏格兰松氨丙基转移酶为种子植物多胺生物合成途径的进化提供了新的线索。
Scots pine aminopropyltransferases shed new light on evolution of the polyamine biosynthesis pathway in seed plants.
机构信息
University of Oulu, Department of Ecology and Genetics, Oulu, Finland.
Natural Resources Institute Finland, Bio-based Business and Industry, Parkano, Finland.
出版信息
Ann Bot. 2018 May 11;121(6):1243-1256. doi: 10.1093/aob/mcy012.
BACKGROUND AND AIMS
Polyamines are small metabolites present in all living cells and play fundamental roles in numerous physiological events in plants. The aminopropyltransferases (APTs), spermidine synthase (SPDS), spermine synthase (SPMS) and thermospermine synthase (ACL5), are essential enzymes in the polyamine biosynthesis pathway. In angiosperms, SPMS has evolved from SPDS via gene duplication, whereas in gymnosperms APTs are mostly unexplored and no SPMS gene has been reported. The present study aimed to investigate the functional properties of the SPDS and ACL5 proteins of Scots pine (Pinus sylvestris L.) in order to elucidate the role and evolution of APTs in higher plants.
METHODS
Germinating Scots pine seeds and seedlings were analysed for polyamines by high-performance liquid chromatography (HPLC) and the expression of PsSPDS and PsACL5 genes by in situ hybridization. Recombinant proteins of PsSPDS and PsACL5 were produced and investigated for functional properties. Also gene structures, promoter regions and phylogenetic relationships of PsSPDS and PsACL5 genes were analysed.
KEY RESULTS
Scots pine tissues were found to contain spermidine, spermine and thermospermine. PsSPDS enzyme catalysed synthesis of both spermidine and spermine. PsACL5 was found to produce thermospermine, and PsACL5 gene expression was localized in the developing procambium in embryos and tracheary elements in seedlings.
CONCLUSIONS
Contrary to previous views, our results demonstrate that SPMS activity is not a novel feature developed solely in the angiosperm lineage of seed plants but also exists as a secondary property in the Scots pine SPDS enzyme. The discovery of bifunctional SPDS from an evolutionarily old conifer reveals the missing link in the evolution of the polyamine biosynthesis pathway. The finding emphasizes the importance of pre-existing secondary functions in the evolution of new enzyme activities via gene duplication. Our results also associate PsACL5 with the development of vascular structures in Scots pine.
背景与目的
多胺是存在于所有活细胞中的小分子代谢物，在植物的许多生理事件中发挥着基本作用。氨基丙基转移酶（APTs）、亚精胺合酶（SPDS）、精胺合酶（SPMS）和热精胺合酶（ACL5）是多胺生物合成途径中的必需酶。在被子植物中，SPMS 是通过基因复制从 SPDS 进化而来的，而在裸子植物中，APTs 大多未被探索，也没有报道过 SPMS 基因。本研究旨在研究苏格兰松（Pinus sylvestris L.）的 SPDS 和 ACL5 蛋白的功能特性，以阐明 APT 在高等植物中的作用和进化。
方法
通过高效液相色谱法（HPLC）分析发芽的苏格兰松种子和幼苗中的多胺，并通过原位杂交分析 PsSPDS 和 PsACL5 基因的表达。生产重组 PsSPDS 和 PsACL5 蛋白，并研究其功能特性。还分析了 PsSPDS 和 PsACL5 基因的结构、启动子区域和系统发育关系。
主要结果
发现苏格兰松组织含有亚精胺、精胺和热精胺。PsSPDS 酶催化亚精胺和精胺的合成。发现 PsACL5 产生热精胺，并且 PsACL5 基因表达定位于胚胎中的发育原形成层和幼苗中的木质部元素中。
结论
与先前的观点相反，我们的结果表明，SPMS 活性不是种子植物被子植物谱系中仅开发的新特征，而且在苏格兰松 SPDS 酶中也存在二次特征。从进化古老的针叶树中发现的多功能 SPDS 揭示了多胺生物合成途径进化中的缺失环节。这一发现强调了在通过基因复制进化新酶活性时，预先存在的次要功能的重要性。我们的结果还将 PsACL5 与苏格兰松血管结构的发育联系起来。
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