探討Puf6與Loc1於核醣體大單元體60S生合成途徑中功能之關聯性

Study the Functional Connection between Puf6 and Loc1 in 60S Biogenesis

楊貽婷(Yi-Ting Yang)

指導教授 ： 羅凱尹

國立臺灣大學/生物資源暨農學院/農業化學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.00159

摘要

在真核細胞中，Puf6與Loc1同時參與兩條重要的途徑: mRNA之不對稱運輸，以及核醣體生合成。此外，Puf6與Loc1在細胞中主要分布位置皆位於核仁。此兩個蛋白結合ASH1 mRNA，將mRNA運輸至子細胞尖端(bud tip)，而mRNA之不對稱分布對於真核細胞之分化相當地重要。另外，Puf6與Loc1也被發現與60S生合成有關聯。若將細胞中PUF6或LOC1移除，pre-rRNA之剪切 (Processing)，60S之出核情形，以及60S的生成量皆會受到影響。然而，目前對於Puf6與Loc1之研究大部分是針對ASH1 mRNA運輸之途徑，關於此兩個蛋白如何於60S生合成途徑執行其功能，目前仍尚未明瞭。
在此篇研究中，發現RPL43是puf6∆之High-copy suppressor，以及Puf6、Rpl43與Loc1三個蛋白質之間具有直接的結合，且於60S生合成途徑中的功能有緊密之關聯性。Loc1為Rpl43之伴護子，並和Puf6協助Rpl43結合60S。且Puf6及Loc1需要彼此才能在正確的時間點結合60S。接著，待Puf6與Loc1執行完其功能後，離開60S則需要Rpl43。

關鍵字

核醣體 ； 核醣體生合成 ； Puf6 ； Loc1 ； Rpl43

並列摘要

Puf6 and Loc1 have two important functional roles in the cells, asymmetric mRNA distribution and ribosome biogenesis. Puf6 and Loc1 are localized predominantly in the nucleolus. They bind ASH1 mRNA, repress its translation, and facilitate the transport to the daughter cells. Asymmetric mRNA distribution is important for cell differentiation. Besides, Puf6 and Loc1 have been shown to involve in 60S biogenesis. In puf6∆ or loc1∆ cells, the pre-rRNA processing and 60S export are impaired and 60S subunits are under-accumulated. The functional studies of Puf6 and Loc1 have been focused on ASH1 mRNA pathway, but the functional roles in 60S biogenesis are still not clear.
In this study, we identified that RPL43 is the high-copy suppressor of puf6∆. Besides, Puf6, Loc1 and Rpl43 have direct physical interaction, and these proteins are tightly connected in 60S biogenesis. Loc1 is the chaperon of Rpl43. Loc1 and Puf6 facilitate the loading of Rpl43. Furthermore, Puf6 and Loc1 depend on each other for joining 60S biogenesis pathway properly. Finally, the recruitment of Rpl43 is required for release of Puf6 and Loc1.

並列關鍵字

Ribosome ； Ribosome biogenesis ； Puf6 ； Loc1 ； Rpl43

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