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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/91872


    Title: AlaRS透過其C端區域結合L構型tRNA的肘部;Evolutionary gain of C-Ala enables AlaRS to target the tRNAAla elbow
    Authors: 安媞卡;Antika, Titi Rindi
    Contributors: 生命科學系
    Keywords: 丙氨酰-tRNA 合成酶;tRNA;C-Ala;秀麗隱桿線蟲;tRNA 結合區域;DNA 結合區域;Alanyl-tRNA synthetase;tRNA;C-Ala;C. elegans;tRNA-binding domain;DNA-binding domain
    Date: 2023-07-18
    Issue Date: 2023-10-04 14:44:53 (UTC+8)
    Publisher: 國立中央大學
    Abstract: Alanyl-tRNA synthetase (AlaRS)是細胞內必要的轉譯酵素之一,它的主要功能是將丙胺酸(alanine)接到相對應的tRNAAla上。AlaRS藉由辨識tRNAAla acceptor stem上的G3:U70鹼基配對來維持其tRNAAla辨識的專一性,這種辨認方式存在幾乎所有物種中。AlaRS的結構含有四個功能區域(包含催化、tRNA辨識、校正、及C-Ala),而且在演化上一直保持這四個功能區域,因此不論是原核或真核生物的AlaRS都是由四個功能區域組成。然而,不同於胺基端的其他三個功能區域,他們在序列及功能上都非常保守,C端區域 (C-Ala)在序列和功能上有著顯著差異。例如,大腸桿菌C-Ala參與了tRNA結合,並參與AlaRS二聚體的形成,但人類細胞質C-Ala卻不參與tRNA結合,而且人類AlaRS是以單體的形式存在。更有趣的是,人類C-Ala雖然失去結合tRNA的能力,卻獲得DNA結合能力。在本論文中,我們發現線蟲C. elegans細胞質C-Ala同時具有tRNA和DNA的結合能力,而且此 C-Ala 能夠結合許多不同種類的tRNA,但是明顯地偏好tRNAAla。我們進一步的實驗發現線蟲C-Ala 可以專一性地辨識tRNAAla D-loop上的G18。值得注意的是:這二個鹼基在演化上非常保守,且參與了tRNA L構型的形成,因此這二個鹼基也廣泛存在非tRNAAla的D-loop上。雖然線蟲粒線體AlaRS的C-Ala比其細胞質AlaRS的C-Ala 短小許多(大約只有四分之一大小),卻也可以同時與DNA及其同源tRNAAla D-loop結合。這項研究解釋了C-Ala如何透過與tRNAAla的D-loop結合,促進 AlaRS 的tRNAAla結合能力及胺醯化活性。;Alanyl-tRNA synthetase (AlaRS) is the enzyme responsible for charging alanine to its cognate tRNAAla. AlaRS is prominent for its ability to specifically recognize tRNAAla through a wobble base pair in the acceptor stem, G3:U70, which is highly conserved in nearly all organisms. AlaRS retains a highly-conserved four-domain structure. Nevertheless, its C-terminal domain (C-Ala) is significantly diverged in sequence and function. For example, E. coli C-Ala mediates tRNA binding and dimerization, while human cytoplasmic C-Ala poorly binds tRNA and forms a monomer. Instead, human C-Ala retains a strong DNA-binding activity. We showed herein that the nematode C. elegans cytoplasmic C-Ala robustly binds both tRNA and DNA. Despite the fact that this C-Ala can bind many different tRNAs with appreciable affinities, with a distinct preference to tRNAAla. As it turns out, Ce-C-Alac specifically recognized the conserved invariant base G18 in the D-loop of tRNAAla through a highly conserved lysine residue, K934. While its mitochondrial counterpart is only one fourth the size of a regular C-Ala domain, it can also bind DNA and its cognate tRNAAla. This study underscores the molecular mechanism of how C-Ala targets AlaRS to the elbow-containing tRNAAla and facilitates its aminoacylation.
    Appears in Collections:[生命科學研究所 ] 博碩士論文

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