阿拉伯芥之聚泛素基因UBQ10、UBQ11和UBQ14的基因表現及啟動子序列分析

Expression and promoter analyses of Arabidopsis polyubiquitin genes, UBQ10, UBQ11 and UBQ14

張淑芝(Shu-Chih Chang)

指導教授 ： 孫智雯

國立臺灣師範大學/理學院/生命科學研究所/碩士(2009年)

摘要

泛素(ubiquitin)是一個由七十六個胺基酸所組成的蛋白質，它廣泛存在真核生物體內。近來的研究發現，阿拉伯芥中泛素主要由五個聚泛素基因所轉錄轉譯出，依其親緣特徵可分成兩群，UBQ3和UBQ4為一群，UBQ10/UBQ11/UBQ14為一群。因此本研究以阿拉伯芥之UBQ10/UBQ11/UBQ14為目標，研究其基因表現的調控機制。將UBQ10/UBQ11/UBQ14的上游序列，依序刪減後接上報導基因，分析報導基因的表現量得知UBQ10的啟動子(promoter)序列上有一正向調控區段(-2044至-1849)、UBQ11的啟動子序列有負向(-798至-577)以及正向(-577至-258)各一的調控區段，而UBQ14的啟動子序列上有一負向調控區段(-714到-636)。利用生物資訊工具調查此三基因的啟動子序列，結果發現三個保守序列(UPE1、UPE2和UPE3)。進一步比較這些基因在不同生長時期、不同溫度及光線處理的基因表現模式，得知UBQ11及UBQ14在低溫處理下會增加基因表現量，但UBQ14在UV-B及黑暗處理下影響會減少表現量。UBQ10表現則不受這些環境因子影響。

關鍵字

聚泛素基因

並列摘要

Ubiquitin (Ub) is a conserved 76-amino acid protein among all eukaryotic organisms. According to previous genetic and molecular studies, the majority of cellular Ub molecules in Arabidopsis are encoded by five polyubiquitin genes. These five genes can be further divided into two subtypes based on the gene structures phylogenic analyses. In this study, we had focused on transcription regulation of the second subtype, UBQ10/UBQ11/UBQ14. The promoter deletion and transient analyses indicated that the positive regulatory regions representing locations between -2044 to -1849, -577 to -258, and -714 to -636 were defined on the UBQ10, UBQ11, UBQ14 promoter sequences, respectively. Besides that, a negative regulatory region (-798 to -577) was also defined on UBQ11 promoter sequence. The promoter sequences of these genes were furthered analyzed by MEME software, and the results indicated three conserved cis-acting elements ubiquitin promoter elements (UPEs). We also compared the expression patterns of UBQ10/UBQ11/UBQ14 during various developmental stages and under different temperatures and light treatments. The results showed that UBQ14 and UBQ11 had a higher expression in low temperature. Moreover, the transcription level of UBQ14 also decreased transcription level under UV-B and dark treatment. In contrast, UBQ10 expression remained constantly under various environmental treatments.

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