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標題: | 阿拉伯芥中CIL (Chloroplast-Import-Apparatus 2 Like)蛋白質之特性分析 Characterization of Arabidopsis CIL (Chloroplast-Import-Apparatus 2 Like) protein |
作者: | Min- Yan Kuo 郭明艷 |
出版年 : | 2002 |
學位: | 碩士 |
摘要: | 植物葉綠體需自細胞質中輸入大量蛋白質以維持其正常運作。葉綠體因而發展出一套特殊運轉機組(translocon complex),用以辨識及輸入葉綠體蛋白質至正確的部位。運轉機組成員中位於外膜者稱為:Toc (translocons at the outer envelope membrane of chloroplasts) proteins;位於內膜者稱為:Tic (translocons at the inner envelope membrane of chloroplasts) proteins。在篩選蛋白質輸入葉綠體機制發生缺失的變株中,我們得到一突變株,造成此缺失的基因:CIA2(Chloroplast-Import-Apparatus 2) 在阿拉伯芥中尚具有一個同源性基因: CIL(Chloroplast-Import-Apparatus 2 Like)。兩者在蛋白質序列上均具有CCT-domain,可能為一種轉錄因數(transcription factor)。已知CIA 2調控數個運轉機組蛋白基因的表現,進而影響蛋白質輸入葉綠體的效率。本篇論文則針對CIL在植物體內的功能作分析。結果顯示,在蛋白質輸入葉綠體的過程中,CIA 2具有較顯著的影響,CIL可能僅提供植物維持一個基本的需求量;但若是同時失去了CIA 2和CIL,則蛋白質輸入葉綠體的過程中會發生嚴重的缺失。然而CIL並不會影響運轉基因的表現,可能是透過不同於CIA 2的方式,對蛋白質輸入葉綠體的效率產生影響。 Chloroplasts are organelles essential for the photoautotrophic growth of plants. To carry out their functions, chloroplasts need to import hundreds of different precursor proteins from the cytosol. Cleavable transit sequences, located at the N-terminus of precursor proteins, target the precursor proteins to chloroplasts. The import process is mediated by a set of translocon complexes located at the chloroplast envelope. To understand the transcriptional regulation of translocon genes, we have previously identified the CIA2 gene, which encodes a nuclear protein containing a CCT- motif.CIA2 regulates the transcription of several translocon genes. Completion of the Arabidopsis genome revealed CIL encodes a homologue of CIA2. Here I report the characterizations of the CIL gene. The two homologues only express in above-ground tissues, especially in leaves. There is less developmental regulation in CIL than in CIA2 expression. For maintaining chloroplast protein import efficiency, CIL plays a basal-level supporting role for CIA2 in mature plants, but both proteins are equally important in younger plants. Unlike CIA2, CIL does not regulate the transcript abundance of translocon genes. In addition, residues 47?50, but not the CCT-motif, are essential for nuclear localization of CIL. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/75353 |
全文授權: | 未授權 |
顯示於系所單位: | 植物科學研究所 |
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