請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/19867
標題: | 研究SUMOylation和phosphorylation在調控端粒長度中所扮演的角色 Investigating the role of SUMOylation and phosphorylation on telomere length regulation |
作者: | "I-Chen, Cheng" 鄭意真 |
指導教授: | 林敬哲 |
關鍵字: | 端粒,磷酸化, telomere,phosphorylation,sumoylation,cdc13, |
出版年 : | 2015 |
學位: | 碩士 |
摘要: | 端粒位於真核染色體末端。線性染色體的末端需要有端粒的存在以保持染色體的完整性。在大多數的真核細胞中,端粒長度是由端粒蛋白協助端粒酶來維持。在酵母菌中,端粒結合蛋白Cdcl3會專一性的結合至單股端粒DNA,保護末端端粒,並在調節端粒酶活性中扮演重要角色。在細胞週期S期晚期Cdcl3會與Est1產生交互作用,將端粒酶帶到端粒上,並激活端粒酶。另一方面,Cdcl3也會與Stn1和Ten1形成三聚體複合物來抑制端粒酶延長端粒。而Cdc13是藉由轉譯後修飾來決定該扮演促進或抑制端粒長度的角色,因此轉譯後修飾對Cdc13來說非常重要。當Cdcl3的Ser249/255發生磷酸化時,會與Est1產生交互作用,以激活端粒酶。而在Ser314/324的磷酸化被發現會負面的調控端粒長度,導致cdcl3Ser314/324突變株會擁有較Cdc13WT稍長端粒。而Cdcl3的Lys909會被SUMO化修飾,且這個修飾對Cdcl3和Stn1之間的交互作用非常重要。針對Cdcl3藉由磷酸化和SUMO化調控Cdcl3與Stn1或Est1相互作用的機制進行了分析。我們發現,在cdc13K909R突變株所發現的稍長的端粒,需要在Ser249/255的位置有發生磷酸化才能變長。且Ser314/324的磷酸化與SUMO化修飾是藉由不同的途徑來負調控端粒長度的。我們的研究連結了磷酸化和SUMO化對端粒之影響。Cdcl3可藉由不同的轉譯後修飾,以規範其與Est1或Stn1相互作用調節端粒酶活性。 Telomeres are the ends of eukaryotic chromosomes. Telomeres are required to maintain chromosome integrity. Telomere length is maintained by telomerase in most eukaryotic cells and is regulated by telomere associated proteins. In yeast Saccharomyces cerevisiae, telomere binding protein Cdc13 binds to single strand telomeric DNA, protects telomere ends, and plays a central role in regulating telomerase activity. Cdc13 interacts with Est1 to recruit and activate telomerase at late S phase of the cell cycle. Cdc13 also forms a trimeric complex with Stn1 and Ten1 to inhibit telomerase. Post-translational modification appears to be important to mediate Cdc13’s function on telomeres. Phosphorylation of Cdc13 at Ser249/255 was shown to be important for the interaction with Est1 to activate telomerase. The Ser314/324 phosphorylation was found to regulate telomere negatively as Cdc13 Ser314/324 mutations cause slightly longer telomere. Here we found that Cdc13 is SUMOylated at Lys909 and this modification is important for the interaction between Cdc13 and Stn1. The mechanism of how Cdc13 phosphorylation and SUMOylation mediate differential Cdc13’s interaction with Stn1 or Est1 is also analyzed. We found that the telomere lengthening in Cdc13K909R required the phosphorylations at Ser249/255. Phosphorylation at Ser314/324 did not appear to affect SUMOylation. Our results implicated a crosstalk between phosphorylation and SUMOylation. Cdc13 might utilize differential modifications to regulate its interactions with Est1 or Stn1 to modulate telomerase activity. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/19867 |
全文授權: | 未授權 |
顯示於系所單位: | 生物化學暨分子生物學科研究所 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-104-1.pdf 目前未授權公開取用 | 1.42 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。