2012年10月31日 訊 /生物谷BIOON/ --人們經(jīng)常認(rèn)為細(xì)胞內(nèi)發(fā)生的蛋白運輸過程與細(xì)胞的年齡無關(guān),。但是在一項新的研究中，中國臺灣中央研究院研究員Hsou-min Li博士領(lǐng)導(dǎo)的一個研究團隊發(fā)現(xiàn)在植物中,，葉綠體年齡差異性地調(diào)節(jié)著蛋白運輸?shù)竭@種細(xì)胞器中,。這一發(fā)現(xiàn)推翻了一個曾被廣泛接受的觀點：這種蛋白運輸過程是與年齡不相關(guān)的,。相關(guān)研究結(jié)果于10月30日發(fā)表在PLoS Biology期刊上。
在這項研究中,，Li博士和同事們研究了不同年齡的豌豆葉子,，結(jié)果發(fā)現(xiàn)運輸?shù)饺~綠體---植物細(xì)胞中進行光合作用的細(xì)胞器---中的蛋白能夠分為三組：第一組偏好運輸?shù)椒浅Ｄ贻p的葉綠體中，第二組沒有特別的偏好,，而第三組偏好運輸?shù)捷^老的葉綠體中,。
由于存在技術(shù)上的困難，蛋白運輸水平上的年齡依賴性調(diào)控一直沒有得到深入的研究,。如今,，利用基因組分析和蛋白質(zhì)分析產(chǎn)生的大通量數(shù)據(jù)，研究人員能夠測試更多的蛋白,，并且能夠證實這種調(diào)控的確存在,，而且每種蛋白受到差異性地的調(diào)控。
在發(fā)現(xiàn)這種新的調(diào)控之后,，Li博士研究團隊然后試圖發(fā)現(xiàn)控制年齡選擇性的信號,。他們發(fā)現(xiàn)就每種蛋白而言，年齡選擇性信號位于控制蛋白運輸?shù)郊?xì)胞器中的信號肽內(nèi),。他們還鑒定出蛋白運輸?shù)捷^老的葉綠體中所必需的信號肽基序,。
Li博士說，他們相信類似的調(diào)控機制可能也存在其他有機體(比如人類)內(nèi)的其他細(xì)胞器中,，而且可能存在信號肽基序允許人們特異性地靶向運輸治療性蛋白到衰老心臟組織中的線粒體內(nèi),。(生物谷Bioon.com)
doi: 10.1371/journal.pbio.1001416
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Differential Age-Dependent Import Regulation by Signal Peptides
Yi-Shan Teng, Po-Ting Chan, Hsou-min L
Gene-specific, age-dependent regulations are common at the transcriptional and translational levels, while protein transport into organelles is generally thought to be constitutive. Here we report a new level of differential age-dependent regulation and show that chloroplast proteins are divided into three age-selective groups: group I proteins have a higher import efficiency into younger chloroplasts, import of group II proteins is nearly independent of chloroplast age, and group III proteins are preferentially imported into older chloroplasts. The age-selective signal is located within the transit peptide of each protein. A group III protein with its transit peptide replaced by a group I transit peptide failed to complement its own mutation. Two consecutive positive charges define the necessary motif in group III signals for older chloroplast preference. We further show that different members of a gene family often belong to different age-selective groups because of sequence differences in their transit peptides. These results indicate that organelle-targeting signal peptides are part of cells' differential age-dependent regulation networks. The sequence diversity of some organelle-targeting peptides is not a result of the lack of selection pressure but has evolved to mediate regulation.
