CONVERGENT TRANSCRIPTION INITIATES FROM OPPOSITELY ORIENTED PROMOTERS WITHIN THE 5' END REGIONS OF DROSOPHILA-MELANOGASTER F ELEMENTS
CONVERGENT TRANSCRIPTION INITIATES FROM OPPOSITELY ORIENTED PROMOTERS WITHIN THE 5' END REGIONS OF DROSOPHILA-MELANOGASTER F ELEMENTS
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DOI：
10.1128/mcb.11.10.5171
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发表时间：
1991-10-01
影响因子：
5.3
通讯作者：
DINOCERA, PP
中科院分区：
文献类型：
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作者：
MINCHIOTTI, G;DINOCERA, PP
果蝇F元件是可移动的，寡核苷酸(A)端DNA序列，可能通过RNA中间体的反转录进行繁殖。在施耐德果蝇II型培养细胞中，将含有与CAT基因融合的全长F元件左侧区域DNA片段的质粒作为模板进行瞬时表达试验。蛋白质和RNA分析鉴定出两个启动子，F（in）和F(out)，转录方向相反。F（in）启动子驱动转录本的合成，转录本在残基+6周围启动，并指向该元素。F（in）可能控制F转位RNA中间体和基因产物的形成，位于转录区内部。对F（in）转录本积累重要的序列包括在+1到+30区间内；另外一个调控元件可能与位于该区域下游的七聚体一致，该七聚体也存在于果蝇f样反转录转座子的5'端区域。对3'缺失衍生物模板活性的分析表明，F(in) RNA的积累水平也取决于位于+175至+218区间的序列的存在。F（out）启动子以与F（in）相反的方向驱动转录。F（out）转录本在+92至+102区间内在附近的位点启动。这些多个RNA起始位点的下游序列不需要F（out）启动子的活性。敲除F（in）启动子的缺失不会损害F（out）转录；相反，在缺乏F（out）启动子的模板中，F（in）启动子的起始仍然发生。在低水平上，这两种启动子在培养细胞中都是活跃的。
Drosophila melanogaster F elements are mobile, oligo(A)-terminated DNA sequences that likely propagate by the retrotranscription of RNA intermediates. Plasmids bearing DNA segments from the left-hand region of a full-length F element fused to the CAT gene were used as templates for transient expression assays in Drosophila Schneider II cultured cells. Protein and RNA analyses led to the identification of two promoters, F(in) and F(out), that transcribe in opposite orientations. The F(in) promoter drives the synthesis of transcripts that initiate around residue +6 and are directed toward the element. F(in), that probably controls the formation of F transposition RNA intermediates and gene products, is internal to the transcribed region. Sequences important for accumulation of F(in) transcripts are included within the +1 to +30 interval; an additional regulatory element may coincide with a heptamer located downstream of this region also found in the 5' end regions of F-like Drosophila retrotransposons. Analysis of the template activity of 3' deletion derivatives indicates that the level of accumulation of F(in) RNA is also dependent upon the presence of sequences located within the +175 to +218 interval. The F(out) promoter drives transcription in the opposite orientation with respect to F(in). F(out) transcripts initiate at nearby sites within the +92 to +102 interval. Sequences downstream of these multiple RNA start sites are not required for the activity of the F(out) promoter. Deletions knocking out the F(in) promoter do not impair F(out) transcription; conversely, initiation at the F(in) promoter still takes place in templates that lack the F(out) promoter. At a low level, both promoters are active in cultured cells.