最近提出异戊二烯是一种信号分子,可以增强对生物和非生物胁迫的耐受性。不是所有的植物都能制造异戊二烯,但迄今为止测试的所有植物都对异戊二烯有反应。我们假设异戊二烯与现有的信号通路相互作用,而不需要新的机制来影响植物。我们分析了异戊二烯响应基因启动子中的顺式调节元件(CREs)以及结合这些启动子元件的相应转录因子,以获得有关异戊二烯信号传导的转录因子和其他蛋白质的线索。使用拟南芥顺式调节元件数据库表征异戊二烯应答基因的启动子区。CREs绑定ARR1、Dof、DPBF,BHLH112,GATA因素,GT-1,MYB,和WRKY转录因子,光响应元件在异戊二烯响应基因的启动子中过量代表;CBF-,HSF-,具有WUS约束力的基序代表性不足。与异戊二烯反应基因启动子中过度代表的CRE相对应的转录因子主要是那些对应激反应很重要的因子:干旱,盐/渗透-,氧化-,食草动物/创伤和病原体应激。超过一半的异戊二烯响应基因包含至少一个IV类(同源域亮氨酸拉链)HD-ZIP家族的TF的结合位点,如GL2,ATML1,PDF2,HDG11,ATHB17。当HD-拉链-环-拉链(ZLZ)结构域与启动子区的L1盒结合时,一个特殊的结构域称为类固醇生成急性调节蛋白相关的脂质转移,或开始域,可以结合配体,如脂肪酸(例如,亚麻酸和亚油酸)。我们测试了异戊二烯是否可能在这样的START结构域中结合。进行分子模拟和建模以测试异戊二烯与IV类HD-ZIP家族含有START结构域的蛋白质之间的相互作用。没有HDG11START结构域的膜渗透,脂质双层内的异戊二烯无法进入该结构域,防止蛋白质与膜结合异戊二烯相互作用。异戊二烯介导的信号与其他生长调节剂和应激信号通路之间的交叉对话,就常见的CRE和转录因子而言,当异戊二烯在植物中进化时,它可以增强异戊二烯排放性状的稳定性,但到目前为止,还不能说异戊二烯是如何被感知以启动信号反应的。
Isoprene has recently been proposed to be a signaling molecule that can enhance tolerance of both biotic and abiotic stress. Not all plants make isoprene, but all plants tested to date respond to isoprene. We hypothesized that isoprene interacts with existing signaling pathways rather than requiring novel mechanisms for its effect on plants. We analyzed the cis-regulatory elements (CREs) in promoters of isoprene-responsive genes and the corresponding transcription factors binding these promoter elements to obtain clues about the transcription factors and other proteins involved in isoprene signaling. Promoter regions of isoprene-responsive genes were characterized using the Arabidopsis cis-regulatory element database. CREs bind ARR1, Dof, DPBF, bHLH112, GATA factors, GT-1, MYB, and WRKY transcription factors, and light-responsive elements were overrepresented in promoters of isoprene-responsive genes; CBF-, HSF-, WUS-binding motifs were underrepresented. Transcription factors corresponding to CREs overrepresented in promoters of isoprene-responsive genes were mainly those important for stress responses: drought-, salt/osmotic-, oxidative-, herbivory/wounding and pathogen-stress. More than half of the isoprene-responsive genes contained at least one binding site for TFs of the class IV (homeodomain leucine zipper) HD-ZIP family, such as GL2, ATML1, PDF2, HDG11, ATHB17. While the HD-zipper-loop-zipper (ZLZ) domain binds to the L1 box of the promoter region, a special domain called the steroidogenic acute regulatory protein-related lipid transfer, or START domain, can bind ligands such as fatty acids (e.g., linolenic and linoleic acid). We tested whether isoprene might bind in such a START domain. Molecular simulations and modeling to test interactions between isoprene and a class IV HD-ZIP family START-domain-containing protein were carried out. Without membrane penetration by the HDG11 START domain, isoprene within the lipid bilayer was inaccessible to this domain, preventing protein interactions with membrane bound isoprene. The cross-talk between isoprene-mediated signaling and other growth regulator and stress signaling pathways, in terms of common CREs and transcription factors could enhance the stability of the isoprene emission trait when it evolves in a plant but so far it has not been possible to say what how isoprene is sensed to initiate signaling responses.