橡胶树酵母双杂交cDNA文库的构建及HbEIN3互作蛋白筛选

Establishment of a yeast two-hybrid cDNA library of Hevea brasiliensis and screening of HbEIN3-interacting proteins

  • 摘要: 【目的】 构建橡胶树酵母双杂交cDNA文库,筛选橡胶树乙烯信号通路中关键转录因子HbEIN3的互作蛋白,挖掘乙烯介导的HbEIN3调控橡胶树抗逆性的潜在因子,为深入解析HbEIN3在橡胶树逆境应答中的调控机制提供理论基础。【方法】 提取橡胶树7-33-97叶片和胶乳的总RNA,分离纯化mRNA并反转录合成cDNA,利用Gateway建库方法构建初级cDNA文库,将初级文库质粒与次级文库载体pGADT7-DEST进行LR重组反应,构建酵母双杂交cDNA文库。克隆截短的HbEIN3基因(编码第1~472位氨基酸,记为HbEIN31-472),并将其连接至诱饵载体pGBKT7上,检测其转录自激活活性。以pGBKT7-HbEIN31-472为诱饵,通过双转法从酵母双杂交cDNA文库中筛选HbEIN3互作的候选蛋白。通过酵母回转验证,进一步验证HbEIN3与候选蛋白的互作关系。【结果】 成功构建橡胶树的酵母双杂交cDNA文库,文库滴度为4.00×106 CFU/mL,文库总量为1.60×107 CFU,插入片段长度不一致,为1000~2000 bp,重组率为100%,符合文库筛选要求。成功构建HbEIN3基因的酵母双杂交诱饵载体pGBKT7-HbEIN31-472,HbEIN3的激活结构域位于蛋白的C端,HbEIN31-472转录自激活活性消失,可用于后续酵母双杂交文库筛选试验。筛选到非特异性脂质转移蛋白(nsLTP)、泛素化修饰相关蛋白、肉桂醇脱氢酶(CAD)等20个与HbEIN3互作的候选蛋白,有14个蛋白富集在信号通路,其中2个蛋白富集在苯丙氨酸、酪氨酸和色氨酸生物合成通路,1个蛋白富集在MAPK信号通路,有1个蛋白富集在NOD样受体信号通路,暗示这些蛋白可能参与HbEIN3响应乙烯信号转导及调节橡胶树抗逆性等过程;其余6个蛋白未被注释或者富集。【结论】 构建的酵母双杂交cDNA文库质量高、库容量达标、插入片段完整性好,成功用于HbEIN3蛋白互作筛选试验。筛选得到20个潜在互作蛋白可能与HbEIN3互作来响应乙烯信号,从而影响橡胶树的抗逆性。本研究结果进一步完善HbEIN3的调控网络,为橡胶树通过乙烯信号途径抵御外界生物和非生物胁迫提供重要的基因资源。

     

    Abstract: 【Objective】 This study aimed to establish a yeast two-hybrid library of Hevea brasiliensis, screen proteins that interacted with HbEIN3, and find out potential factors in ethylene-mediated HbEIN3 that regulated stress resistance in Hevea brasiliensis, so as to provide a theoretical basis for further elucidating the regulation mechanism of HbEIN3 in stress responses in Hevea brasiliensis. 【Method】 Total RNA was extracted from the leaves and latex of Hevea brasiliensis cultivar 7-33-97, followed by mRNA isolation and purification, after which cDNA was synthesized. A primary cDNA library was established using the Gateway method. The plasmids from the primary library were recombined with the se-condary vector pGADT7-DEST via LR recombination to generate a yeast two-hybrid cDNA library. A truncated HbEIN3 gene fragment (encoding amino acids 1-472, designated as HbEIN31-472) was cloned into the bait vector pGBKT7 to test its transcriptional self-activation activity. Using pGBKT7-HbEIN31-472 as the bait, candidate HbEIN3-interacting proteins were screened from the yeast two-hybrid cDNA library via the dual transformation approach. Yeast retransformation assays were used to further confirm the interactions between HbEIN3 and the candidate proteins. 【Result】 A cDNA library of Hevea brasiliensis was successfully established,with a titer of 4.00×106 CFU/mL,a total library size of 1.60×107 CFU,insert sizes ranging from 1000 to 2000 bp,and a recombination rate of 100%,meeting the requirements for library scree-ning. The yeast two-hybrid bait vector pGBKT7-HbEIN31-472 of the HbEIN3 gene was generated. The domain activated by HbEIN3 was localized at the C-terminal of the protein; HbEIN31-472 showed no self-activation, making it suitable for subsequent yeast two-hybrid library screening assays. A total of 20 candidate HbEIN3-interacting proteins were identified, including non-specific lipid transfer proteins (nsLTP), ubiquitination-related proteins, and cinnamyl alcohol dehydro-genase (CAD). There were twelve proteins enriched in signaling pathways: two proteins were enriched in the phenylalanine, tyrosine, and tryptophan biosynthesis pathway; one protein was enriched in the MAPK signaling pathway; and one protein was enriched in the NOD-like receptor signaling pathway, suggesting that these proteins might be involved in processes such as HbEIN3-mediated ethylene signal transduction and the regulation of stress resistance in Hevea brasiliensis. The remaining eight proteins were either unannotated or not enriched in any pathway. 【Conclusion】 The established yeast two hybrid cDNA library exhibits high quality, sufficient library capacity, and complete insert diversity, and it is successfully used to screen HbEIN3-interacting proteins. The 20 candidate interacting proteins identified in this study may interact with HbEIN3 to respond to ethylene signaling, thereby influencing the stress resistance of rubber trees. The results further refine the regulatory network of HbEIN3 and provide important genetic resources for understanding how Hevea brasiliensis copes with biotic and abiotic stresses through the ethylene signaling pathway.

     

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