Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju 500-757, Korea.
Mol Cells. 2012 Jun;33(6):617-26. doi: 10.1007/s10059-012-0080-8. Epub 2012 May 17.
Translationally controlled tumor protein (TCTP), also termed P23 in human, belongs to a family of calcium- and tubulin-binding proteins, and it is generally regarded as a growth-regulating protein. Recently, Arabidopsis TCTP (AtTCTP) has been reported to function as an important growth regulator in plants. On the other hand, plant TCTP has been suggested to be involved in abiotic stress signaling such as aluminum, salt, and water deficit by a number of microarray or proteomic analyses. In this study, the biological functions of AtTCTP were investigated by using transgenic Arabidopsis plants overexpressing AtTCTP. Interestingly, AtTCTP overexpression enhanced drought tolerance in plants. The expression analysis showed that AtTCTP was expressed in guard cells as well as in actively growing tissues. Physiological studies of the overexpression lines showed increased ABA- and calcium-induced stomatal closure ratios and faster stomatal closing responses to ABA. Furthermore, in vitro protein-protein interaction analysis confirmed the interaction between AtTCTP and microtubules, and microtubule cosedimentation assays revealed that the microtubule binding of AtTCTP increased after calcium treatment. These results demonstrate that the overexpression of AtTCTP confers drought tolerance to plants by rapid ABA-mediated stomatal closure via the interaction with microtubules in which calcium binding enhances the interaction. Collectively, the present results suggest that the plant TCTP has molecular properties similar to animal TCTPs, such as tubulin- and calcium-binding, and that it functions in ABA-mediated stomatal movement, in addition to regulating the growth of plants.
翻译控制肿瘤蛋白（TCTP），在人类中也称为 P23，属于钙和微管结合蛋白家族，通常被认为是一种生长调节蛋白。最近，拟南芥 TCTP（AtTCTP）被报道在植物中作为一种重要的生长调节剂发挥作用。另一方面，通过许多微阵列或蛋白质组学分析表明，植物 TCTP 参与了非生物胁迫信号转导，如铝、盐和水分亏缺。在这项研究中，通过过表达 AtTCTP 的转基因拟南芥植物来研究 AtTCTP 的生物学功能。有趣的是，AtTCTP 的过表达增强了植物的耐旱性。表达分析表明，AtTCTP 在保卫细胞以及活跃生长的组织中表达。过表达系的生理研究表明，ABA 和钙诱导的气孔关闭比例增加，以及对 ABA 的气孔关闭反应更快。此外，体外蛋白-蛋白相互作用分析证实了 AtTCTP 与微管之间的相互作用，并且微管共沉淀测定表明，钙处理后 AtTCTP 与微管的结合增加。这些结果表明，AtTCTP 的过表达通过与微管的相互作用快速介导 ABA 诱导的气孔关闭来赋予植物耐旱性，其中钙结合增强了相互作用。总的来说，这些结果表明，植物 TCTP 具有与动物 TCTP 相似的分子特性，如微管和钙结合，并且除了调节植物生长外，它还参与了 ABA 介导的气孔运动。
