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標題: | 穀胱甘肽在阿拉伯芥耐熱性反應中的作用 The Role of Glutathione in Thermotolerance and Heat Shock Response in Arabidopsis thaliana |
作者: | Tzu-Ying Yang 楊子瑩 |
指導教授: | 常怡雍(Yee-Yung Charng) |
關鍵字: | 熱逆境反應,耐熱性,穀胱甘肽,γ-谷氨酰半胱氨酸合成酶,阿拉伯芥, Heat stress response,thermotolerance,glutathione,γ-glutamylcysteine synthetase,Arabidopsis thaliana, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 穀胱甘肽 (Glutathione) 在細胞中扮演著維持氧化還原恆定的重要角色。先前研究發現,經過 buthionine sulfoximine 處理後的動物細胞,其穀胱甘肽的含量減少,也讓耐熱性和主要的熱休克蛋白的合成受到抑制。為了了解穀胱甘肽的含量是否會影響植物的耐熱性和熱休克反應,此研究對穀胱甘肽合成相關的阿拉伯芥突變種 (cad2-1、pad2-1和zir1) 進行了四種不同的耐熱性測定。所有突變種在四種熱處理條件下皆顯示了熱敏感的表現型,說明了穀胱甘肽對於植物耐熱的重要性。在正常條件和熱處理後,突變種中的穀胱甘肽和氧化型穀胱甘肽 (oxidized glutathione) 的含量有顯著地降低。外加 10 mM 的穀胱甘肽使得pad2-1 恢復部分的耐熱性。在熱處理前後,熱休克蛋白 HSP101、HSP90、HSP70、sHSP-CI、HSA32 和 HSFA2 的表現量並不會受到穀胱甘肽含量影響。蛋白質沈澱分離分析發現造成 pad2-1 的熱敏感性的原因和 hsp101 是有所不同的,暗示穀胱甘肽的缺乏不至於導致分子伴侶功能的喪失。在突變種中,NAD+-異檸檬酸脫氫酶的活性有些微但顯著的下降,顯示穀胱甘肽的含量可能會影響某些氧化還原調節蛋白的功能。因此,在植物和動物中,穀胱甘肽對於熱休克反應之調節機制並不相同。結果也顯示穀胱甘肽在阿拉伯芥中有著抵抗熱逆境的重要作用。 Glutathione (GSH) is an important metabolite that functions in maintaining the cellular redox homeostasis in response to stresses. The reduction of glutathione content upon buthionine sulfoximine treatment results in the inhibition of thermotolerance acquisition and major heat shock proteins (HSPs) synthesis during heat acclimation in animal cells. To investigate whether the level of glutathione influences the thermotolerance and heat shock response in plants, the glutathione deficiency mutants (cad2-1, pad2-1, and zir1) in Arabidopsis were subjected to four distinct thermotolerance assay. All the mutants showed heat-sensitive phenotypes, indicating that glutathione is vital for thermotolerance. Analysis of the GSH/GSSG (oxidized glutathione) content by ultra-performance liquid chromatography mass spectrometry showed that the GSH/GSSG levels were dramatically reduced in the mutants under both normal and heat stress conditions. The thermotolerance of pad2-1 can be partially restored under heat stress conditions by treating with exogenous glutathione at 10 mM. Quantitative RT-PCR and western blotting analysis showed that the abundance of heat-inducible proteins, i.e. HSP101, HSP90, HSP70, sHSP-CI, HSA32, and HSFA2, were not significantly affected in the mutants before and after heat treatment. The thermo-sensitivity of pad2-1 was not due to compromised proteostasis, suggesting that glutathione deficiency does not substantially affect chaperone functions. The activity of NAD+-dependent isocitrate dehydrogenase decreased slightly but significantly in the mutants, indicating that the glutathione content may influence function of some redox-regulated proteins. Hence, the mechanisms of glutathione-mediated heat stress response in plants and animals may not be the same. Glutathione plays a pivotal role in Arabidopsis in conferring heat tolerance. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/54640 |
DOI: | 10.6342/NTU202002237 |
全文授權: | 有償授權 |
顯示於系所單位: | 生化科技學系 |
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