Jiang Jia-Fu, Han Ye, Xing Li-Jing, Xu Yun-Yuan, Xu Zhi-Hong, Chong Kang
Research Center for Molecular and Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, the Chinese Academy of Sciences, Beijing 100093, China.
Toxicon. 2006 Jan;47(1):133-9. doi: 10.1016/j.toxicon.2005.10.010. Epub 2005 Dec 13.
Lectin plays an important role in defense signaling in plants. A few genes of this family have been cloned. Here we report on a mannose-specific jacalin-related lectin in rice. Using sequence information of wheat gene VER2, which we had previously cloned, we were able to amplify a cDNA of OsJAC1 from Oryza sativa by RT-PCR. The cDNA of OsJAC1 was 1172 bp and contained a 921-bp open reading frame (ORF) encoding dirigent (amino acids 26-139) and jacalin (amino acids 175-305) domains of 306 amino acids. Comparison of the OsJAC1 sequence with those of other lectins (jacalin) from rice, wheat and other species revealed that OsJAC1 had the 12 amino acid positions conserved in all mannose-binding lectins. Semi-quantitative RT-PCR revealed that OsJAC1 expression was present in stems, leaves and young spikes but not young roots; the expression was high in leaves and low in stems and spikes. And methyl jasmonate could induce the expression of OsJAC1. To test the activity of OsJAC1, the jacalin domain at the C-terminal was expressed in E. coli. BL21 (DE3). The purified recombinant protein could agglutinate red blood cells of rabbit, and the agglutination activity was strongly inhibited by mannose compared with other carbohydrates. These results indicate that lectin with dirigent and jacalin domains exists in rice as well as wheat. This is the first report of cDNA cloning of mannose-binding jacalin-related lectin with a dirigent domain in N-terminal region from O. sativa.
凝集素在植物的防御信号传导中发挥着重要作用。该家族的一些基因已被克隆。在此，我们报道了水稻中一种甘露糖特异性的与jacalin相关的凝集素。利用我们之前克隆的小麦基因VER2的序列信息，通过逆转录聚合酶链反应（RT-PCR）从水稻中扩增出了OsJAC1的cDNA。OsJAC1的cDNA为1172 bp，包含一个921 bp的开放阅读框（ORF），编码由306个氨基酸组成的 dirigent结构域（氨基酸26 - 139）和jacalin结构域（氨基酸175 - 305）。将OsJAC1序列与来自水稻、小麦和其他物种的其他凝集素（jacalin）序列进行比较，发现OsJAC1在所有甘露糖结合凝集素中具有12个保守的氨基酸位点。半定量RT-PCR显示，OsJAC1在茎、叶和幼穗中表达，但在幼根中不表达；在叶中表达量高，在茎和穗中表达量低。茉莉酸甲酯可诱导OsJAC1的表达。为了检测OsJAC1的活性，将C端的jacalin结构域在大肠杆菌BL21（DE3）中表达。纯化的重组蛋白能够凝集兔红细胞，与其他碳水化合物相比，甘露糖对凝集活性有强烈抑制作用。这些结果表明，水稻和小麦中都存在具有dirigent和jacalin结构域的凝集素。这是关于从水稻中克隆N端区域具有dirigent结构域的甘露糖结合jacalin相关凝集素cDNA的首次报道。
