Identification of AtSM34, a novel tonoplast intrinsic protein-interacting polypeptide expressed in response to osmotic stress in germinating seedlings

作     者：LI LiJuan REN Fei WEI PengCheng CHEN QiJun CHEN Jia WANG XueChen 

作者机构：State Key Laboratory of Plant Physiology and Biochemistry College of Biological Sciences China Agricultural University Beijing 100193 China Institute of Forestry and Pomology Beijing Academy of Agriculture and Forestry Sciences Beijing 100093 China 

出 版 物：《Chinese Science Bulletin》 (中国科学通报)

年 卷 期：2011年第56卷第33期

页      面：3518-3530页

核心收录：

学科分类：09[农学] 0903[农学-农业资源与环境] 

基　　金：supported by the National Natural Science Foundation of China (30770193) the National Basic Research Program of China (2006CB100100) the "111 Project" (B06003) 

主　　题：蛋白质相互作用 渗透胁迫 液泡膜 幼苗 多肽 酵母双杂交系统 组织化学染色 鉴定 

摘      要：Aquaporins are implicated in a wide variety of plant physiological processes, although the mechanisms involved in their regulation are not fully understood. To gain further insight into the regulatory factors involved in this process, we used a yeast two-hybrid system to screen for potential binding partners to the Arabidopsis tonoplast intrinsic protein (TIP) AtTIP1;1. This was the first protein identified to be associated with high water permeability in vacuolar membranes from Arabidopsis thaliana. Using AtTIP1;1 as bait, a novel binding protein was identified in both yeast and plant cells. This prey protein, named AtSM34, was a 309 aa polypeptide with a predicted molecular mass of 34 kD and contained a single MYB/SANT-like domain. AtSM34 promoter:: GUS histochemical staining analysis detected AtSM34 expression in flowers, stems and leaves, particularly in the vascular tissues, in response to osmotic stress. AtSM34 expression was localized in the endoplasmic reticulum membrane, and sequence deletion analysis revealed that the N-terminal coding region (amino acids 1-83) was critical for this localization. Overexpression of AtSM34 resulted in hypersensitivity to exogenous mannitol, sorbitol and abscisic acid, and caused a significant delay in germination. AtSM34 interacted with AtTIP1;2 and AtTIP2;1, which are essential proteins for modulation of tonoplast permeability and highly expressed in germinating seedlings. These data indicate AtSM34 is a novel TIPs binding protein involved in the osmotic stress response of seedlings at an early stage of development.