吳世雄臺灣大學：生化科學研究所陳則安Chen, Tse-AnTse-AnChen2007-11-262018-07-062007-11-262018-07-062004http://ntur.lib.ntu.edu.tw//handle/246246/52746HU蛋白，一種在原核生物中的類組織蛋白，跟細菌的類核物質相互關連，在細菌複製起始、調節轉錄、特定序列重組上扮演結構性的角色。為了能夠更加瞭解Lon酵素蛋白在調節HU蛋白上的角色，純化出來的Bt-Lon跟來自Bacillus subtilis 的HU蛋白定溫培養。Lon以ATP相關的方式有選擇性的分解Bs-HU，證實了Lon直接辨識並分解特定受質的能力。HU最初被分解的序列是在Leu44-Ile45 和Ala57-Arg58，也正是HU 的DNA結合區域所在。Plasmid DNA和雙股DNA均會增加Lon 分解HU的能力，但是plasmid DNA影響比較大。即使一開始HU的切點是在DNA的結合位，在HU剛開始分解的階段，HU的分解並不會影響HU的DNA結合能力。要到降解兩小時候，HU的DNA結合能力才開始下降。HU對DNA結構的改變，更可以被Lon酵素還原。 這是第一篇關於DNA結合蛋白HU是Lon蛋白酵素的一種生理受質，且Lon也麻ル圁U的分解可以參與基因調節。HU, a prokaryotic histone-like protein, associates with bacterial nucleoids and plays architectural roles in replication initiation, transcription regulation and site-specific recombination. To gain an insight into the role of Lon protease in regulation of HU, the purified Bt-Lon was incubated with HU of Bacillus subtilis (Bs-HU). Lon selectively degraded Bs-HU in an ATP-dependent manner, thus confirming the ability of Lon to directly recognize and degrade specific substrates. Cleavage occurred at Leu44-Ile45 and Ala57-Arg58 peptide bonds in the early period of degradation, which are known to be in the DNA-binding motif of Bs-HU. Plasmid DNA and ds-DNA can both enhance proteolysis, with plasmid being better enhancer than ds-DNA . In addition, the degradation of Bs-HU by Bt-Lon in the early period does not influence its ability to bind single-stranded DNA even removing the DNA-binding motif; however, the degradation causes the loss of the DNA-binding ability after incubation with Bt-Lon for 2 h. Furthermore, the DNA conformation altered by Hu can be reformed from the degradation of HU by Bt-Lon. This is the first example to show that HU, a DNA binding protein, is a physiological substrate of Lon protease and Lon protease is probably involved in the regulation of gene expression by degradation of HU.ABSTRACT………………………………………………………………..i 中文摘要………………………………………………………ii LIST OF ABBREVIATIONS…………………………………………iii MATERIALS AND METHODS………………………………………………8 RESULTS AND DISCUSSION……………………………………………25 CONCLUSION…………………………………………………………..31 FIGURES……………………………………………………………….33 REFERENCES………………………………………………………...471511149 bytesapplication/pdfen-USDNA結合蛋白Lon蛋白HU蛋白HU proteinLon proteinDNA binding proteinotherhttp://ntur.lib.ntu.edu.tw/bitstream/246246/52746/1/ntu-93-R91242021-1.pdf