阿拉伯芥F-box蛋白EID1透過調控熱休克因子結合蛋白影響後天耐熱性

Abstract

隨著全球暖化日益嚴重，了解植物耐熱性與其在高溫下的調控機制也越發重要。在過往的研究中顯示，植物主要會倚賴由大量轉錄因子所組成的熱休克反應來應對高溫逆境，同時其中的各個重要蛋白的轉譯後修飾作用在熱逆境調控中也扮演了重要的角色，如泛素化、類小泛素化修飾、磷酸化、組蛋白修飾。前人研究中發現SCF E3 ligase的組成蛋白之一，F-box 蛋白EID1的突變株有著較高的植物耐熱性，但詳細的機制仍尚未闡明。在本篇論文中，我發現eid1突變株有著較弱的短期後天耐熱性，且發現EID1能和HSBP及HSA32相互作用，同時HSBP位於EID1的下游。更進一步研究發現，EID1能夠透過穩定HSBP蛋白、影響HSBP的次細胞定位、並影響最終下游Hsp70和Hsp101的基因轉錄量。此外，初步研究結果發現雖然EID1可以增強HSBP的泛素化程度，但並不會導致HSBP透過26S proteasome降解，因此泛素化如何調控HSBP的功能，仍需更多證據才能證明。最後，我們的研究結果證實了EID1能夠透過正向調控HSBP，負向調控短期後天耐熱性下的Hsp70和Hsp101的轉錄量。

As global warming intensifies, understanding plant heat tolerance and their regulatory mechanisms under high temperatures becomes increasingly important. Previous research has shown that plants primarily rely on a heat shock response (HSR) involving numerous transcription factors to cope with heat stress. However, post-translational modifications (PTMs) of key proteins, such as ubiquitination, SUMOylation, phosphorylation, and histone modifications, also play crucial roles in heat stress regulation. Previous studies found that mutations in EID1, an F-box protein component of the SCF E3 ligase complex, result in enhanced plant heat tolerance with unknown mechanisms. In this study, I discovered that eid1 mutants exhibit reduced short-term acquired thermotolerance (SAT). Additionally, I found that EID1 interacts with HSBP and HSA32, with HSBP acting downstream of EID1. Further investigations revealed that EID1 positively regulates HSBP by stabilizing its protein levels and influencing its subcellular localization. These actions ultimately affect the transcription levels of downstream genes Hsp70 and Hsp101. Although EID1 increased HSBP ubiquitination in my preliminary analysis, it did not cause HSBP degradation via the 26S proteasome-mediated pathway. Further information is required to determine whether HSBP function is connected to its ubiquitination levels. Finally, our findings confirm that EID1 positively regulates HSBP, thereby lowering the transcription levels of Hsp70 and Hsp101 during short-term acquired thermotolerance.