State Key Laboratory of Tree Genetics and Breeding (Northeast Forestry University), 26 Hexing Road, Harbin, China.
BMC Plant Biol. 2012 Jul 26;12:118. doi: 10.1186/1471-2229-12-118.
The eukaryotic translation initiation factor 5A (eIF5A) promotes formation of the first peptide bond at the onset of protein synthesis. However, the function of eIF5A in plants is not well understood.
In this study, we characterized the function of eIF5A (TaeIF5A1) from Tamarix androssowii. The promoter of TaeIF5A1 with 1,486 bp in length was isolated, and the cis-elements in the promoter were identified. A WRKY (TaWRKY) and RAV (TaRAV) protein can specifically bind to a W-box motif in the promoter of TaeIF5A1 and activate the expression of TaeIF5A1. Furthermore, TaeIF5A1, TaWRKY and TaRAV share very similar expression pattern and are all stress-responsive gene that functions in the abscisic acid (ABA) signaling pathway, indicating that they are components of a single regulatory pathway. Transgenic yeast and poplar expressing TaeIF5A1 showed elevated protein levels combined with improved abiotic stresses tolerance. Furthermore, TaeIF5A1-transformed plants exhibited enhanced superoxide dismutase (SOD) and peroxidase (POD) activities, lower electrolyte leakage and higher chlorophyll content under salt stress.
These results suggested that TaeIF5A1 is involved in abiotic stress tolerance, and is likely regulated by transcription factors TaWRKY and TaRAV both of which can bind to the W-box motif. In addition, TaeIF5A1 may mediate stress tolerance by increasing protein synthesis, enhancing ROS scavenging by improving SOD and POD activities, and preventing chlorophyll loss and membrane damage. Therefore, eIF5A may play an important role in plant adaptation to changing environmental conditions.
真核翻译起始因子 5A（eIF5A）促进蛋白质合成起始时第一个肽键的形成。然而，eIF5A 在植物中的功能尚不清楚。
本研究从柽柳中鉴定了 eIF5A（TaeIF5A1）的功能。分离了长度为 1486bp 的 TaeIF5A1 启动子，并鉴定了启动子中的顺式作用元件。WRKY（TaWRKY）和 RAV（TaRAV）蛋白可以特异性结合 TaeIF5A1 启动子中的 W 盒基序，并激活 TaeIF5A1 的表达。此外，TaeIF5A1、TaWRKY 和 TaRAV 的表达模式非常相似，都是应激响应基因，在脱落酸（ABA）信号通路中发挥作用，表明它们是单个调控通路的组成部分。表达 TaeIF5A1 的转基因酵母和杨树表现出提高的蛋白水平，同时提高了非生物胁迫耐受性。此外，在盐胁迫下，TaeIF5A1 转化的植物表现出增强的超氧化物歧化酶（SOD）和过氧化物酶（POD）活性、较低的电解质渗漏和较高的叶绿素含量。
这些结果表明，TaeIF5A1 参与非生物胁迫耐受性，并且可能受到转录因子 TaWRKY 和 TaRAV 的调节，这两个转录因子都可以结合 W 盒基序。此外，TaeIF5A1 可能通过增加蛋白质合成、通过提高 SOD 和 POD 活性来增强 ROS 清除、防止叶绿素损失和膜损伤来介导胁迫耐受性。因此，eIF5A 可能在植物适应不断变化的环境条件中发挥重要作用。
