- 期刊
核糖體第二轉錄區間的二級結構及其在親緣分析上的應用
Secondary Structure of Ribosomal Internal Transcribed Spacer 2 (ITS2) and Its Application in Phylogenetic Analysis
摘要
核糖體廣泛分布自細菌到脊椎動物的細胞中，為生物體內蛋白質合成的系統。核糖體不僅在顯微結構上非常類似，甚至在核糖核酸分子序列也有相當程度的保守性。負責製造核糖體去氧核糖核酸分子的基因序列（即核糖體去氧核糖核酸基因）包含了演化速度較慢的譯碼基因，包括5.8S、小次單元與大次單元，以及介於這些單元之間，演化速度較快的轉錄區間。核糖體去氧核糖核酸不同演化速度的序列片段，提供研究不同分類階層親緣分析時所需的分子遺傳標誌。核糖體轉錄區間的去氧核糖核酸分子序列因具有高度變異，常被選為近緣種以及族群遺傳研究的分子遺傳標誌。但是由於轉錄區間較高的變異性常伴隨著較多的插入與剔除的位點，而造成序列排序時鑑定同源序列的困難。最近的研究發現，從酵母菌到脊椎動物，其核糖體第二轉錄區間二級結構都具有類似的核心區域。此核心區域為四或五個核甘酸相互鍵結的折疊區圍繞著此核心，統稱為環狀模式。折疊區在核糖體分子序列加工形成蛋白質合成系統時，扮演了一個重要的角色。因此，藉由核糖體第二轉錄區間二級結構的保守性，我們可以將變異性較大的序列做正確性的排序修正，增加親緣分析上的可信度。本文將藉由文獻回顧整理過去對核糖體第二轉錄區間初級核甘酸序列與二級結構的研究，並以造礁珊瑚為例說明核糖體第二轉錄區間二級結構的環狀模式以及其在親緣分析上的應用。
並列摘要
Ribosome is a universal organelle in all organisms that specifies for protein synthesis. Ribosome not only highly resemble in its ultrastructure, but the encoded ribosomal DNA (rDNA) sequences also show high conservation among taxa. The structure of rDNA genes includes three coding regions, 5.8S, small subunit, and large subunit. Two internal transcribed spacer (ITS), ITS1 and ITS2, span between 5.8S and small subunit rDNA (ssrDNA) and between 5.8S and large subunit rDNA (IsrDNA) respectively. These different regions of rDNA provide the genetic markers for a wide range of phylogenetic analyses. The rDNA ITS region is served as a potential marker to resolve the phylogenetic relationship at closely-related species level or population structure due to its high evolutionary rate. The high ITS variation caused by point mutations and large pieces of insertion and deletion, on the other hand, has made the identification of homologous sequences more difficult. Recent studies on yeasts, plant, and vertebrates suggested a conservative secondary structure can be identified, thus providing a core for readjusting the homologous sequence regions in the ITS alignment. In this report, the rDNA ITS2 molecular characteristic, secondary structure, and function are reviewed. Examples from the secondary structure scleractinian ITS2 are used to demonstrate the construction of secondary structure and its application in phlyogenetic analysis.
延伸閱讀
- Lee, Y. J. (2018). 高通量分析信使核糖核酸的二級結構對轉譯起始的影響 [master's thesis, National Taiwan University]. Airiti Library. https://doi.org/10.6342/NTU201803699
- Lin, J. H. (2008). 細菌物種基因體中非編碼小片段核糖核酸之預測 [master's thesis, National Central University]. Airiti Library. https://www.airitilibrary.com/Article/Detail?DocID=U0031-0207200917355208
- Huang, Y. S. (2019). 探討小分子核糖核酸在Treg-of-B細胞中所扮演的角色 [master's thesis, National Taiwan University]. Airiti Library. https://doi.org/10.6342/NTU201902720
- Wang, C. L., Chang, P. F. L., Lin, Y. H., Malkus, A., Gao, L. Y., & Ueng, P. P. (2009). Group I Introns in Small Subunit Ribosomal DNA (SSU-rDNA) of Cereal Phaeosphaeria Species. Botanical Studies, 50(2), 137-147. https://www.airitilibrary.com/Article/Detail?DocID=1817406X-200904-50-2-137-147-a
- 陳建樺（2008）。Phylogenetic Analysis Using Nuclear-Encoded Mitochondrial Proteins〔碩士論文，亞洲大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0118-1511201215455507