Intracellular targeting of Gag proteins of the Drosophila telomeric retrotransposons.
Intracellular targeting of Gag proteins of the Drosophila telomeric retrotransposons.
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果蝇端粒逆转录转座子 Gag 蛋白的细胞内靶向。
DOI：
10.1128/jvi.77.11.6376-6384.2003
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发表时间：
2003
影响因子：
5.4
通讯作者：
Pardue,M-L
中科院分区：
文献类型：
--
作者：
Rashkova,S;Athanasiadis,A;Pardue,M-L
果蝇有两个非长末端重复（non-LTR）反转录转座子，它们是独特的，因为它们在染色体维持中有明确的作用。这些元件，HeT-A和TART，通过连续的转座延伸染色体末端，产生长阵列的头到尾重复序列。这些阵列似乎类似于其他生物染色体上端粒酶产生的阵列。而其他非LTR反转录转座子转座到许多染色体位点，HeT-A和TART转座仅转座到染色体末端。虽然HeT-A和TAT属于非LTR反转录转座子的不同亚家族，但它们编码非常相似的Gag蛋白，这表明Gag蛋白参与了它们独特的转座靶向。我们最近发现两种Gags都能有效地定位于HeT-AGag形成与端粒相关结构的细胞核，除非HeT-AGag存在，否则TARTGag不与端粒相关，这表明HeT-AGag提供端粒靶向的共生关系。我们现在报告的研究，以确定负责这些蛋白质的细胞内靶向的不同方面的氨基酸区域。绿色荧光蛋白标记的缺失衍生物在培养的果蝇细胞中表达。这些蛋白质的细胞内定位显示如下。(i)几个地区，直接亚细胞定位或集群的形成被发现在这两个加格，并位于两个蛋白质的等效区域。(ii)对端粒结合重要的区域仅存在于HeT-AGag中。它们存在于蛋白质的几个位置，不是冗余的，并且不能反式互补。(iii)含有锌关节和主要同源区基序的区域，逆转录病毒Gags的特征，参与端粒Gags的蛋白质-蛋白质相互作用，因为它们在逆转录病毒Gags中。
Drosophilahas two non-long-terminal-repeat (non-LTR) retrotransposons that are unique because they have a defined role in chromosome maintenance. These elements,HeT-AandTART, extend chromosome ends by successive transpositions, producing long arrays of head-to-tail repeat sequences. These arrays appear to be analogous to the arrays produced by telomerase on chromosomes of other organisms. While other non-LTR retrotransposons transpose to many chromosomal sites,HeT-AandTARTtranspose only to chromosome ends. AlthoughHeT-AandTARTbelong to different subfamilies of non-LTR retrotransposons, they encode very similar Gag proteins, which suggests that Gag proteins are involved in their unique transposition targeting. We have recently shown that both Gags localize efficiently to nuclei whereHeT-AGag forms structures associated with telomeres.TARTGag does not associate with telomeres unlessHeT-AGag is present, suggesting a symbiotic relationship in whichHeT-AGag provides telomeric targeting. We now report studies to identify amino acid regions responsible for different aspects of the intracellular targeting of these proteins. Green fluorescent protein-tagged deletion derivatives were expressed in culturedDrosophilacells. The intracellular localization of these proteins shows the following. (i) Several regions that direct subcellular localizations or cluster formation are found in both Gags and are located in equivalent regions of the two proteins. (ii) Regions important for telomere association are present only inHeT-AGag. These are present at several places in the protein, are not redundant, and cannot be complemented intrans. (iii) Regions containing zinc knuckle and major homology region motifs, characteristic of retroviral Gags, are involved in protein-protein interactions of the telomeric Gags, as they are in retroviral Gags.