Two promoters within the psbK-psbI-trnG gene cluster in tobacco chloroplast DNA
Two promoters within the psbK-psbI-trnG gene cluster in tobacco chloroplast DNA
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DOI：
10.1007/bf00326241
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发表时间：
1991-08
期刊：
影响因子：
2.5
通讯作者：
B. Meng;T. Wakasugi;M. Sugiura
中科院分区：
文献类型：
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作者：
B. Meng;T. Wakasugi;M. Sugiura
研究了烟草叶绿体中2. 6 kbppsbK-psbI-trnG簇的转录。该簇以线性序列包含编码光系统II的两种低分子量多肽K和I（分别为psbK和psbI）和tRNAGly（UCC）（trnG）的基因。北方印迹杂交显示，最大的转录本（2.6 kb）与topsbK、psbI和trnG杂交，但不与随后的trnR-UCU杂交。还检测到10个范围从0.1到1.3 kb的其他转录本。其中三个转录本与位于相对DNA链上的trnS-GCU产生的不同转录本重叠。S1作图和引物延伸实验表明，这些多个转录本包含8个不同的5′端。通过体外加帽实验，确定其中两个为转录起始位点，一个位于psbK上游163 bp处，另一个位于trnG上游6 bp处。通过S1作图确定转录本的3′端，一个位于psbI和trnG之间，另一个位于trnG的末端。对trnG双启动子的存在进行了讨论。
Transcription of the 2.6 kbppsbK-psbI-trnGcluster in tobacco chloroplasts has been studied. This cluster contains, in linear sequence, the genes encoding two low-molecular-mass polypeptides, K and I, of photosystem II (psbKandpsbI, respectively), and tRNAGly(UCC) (trnG). Northern blot hybridization revealed that the largest transcript (2.6 kb) hybridizes topsbK, psbIandtrnG, but not to the followingtrnR-UCU. Ten other transcripts ranging from 0.1 to 1.3 kb were also detected. Three of these transcripts overlap the divergent transcript arising fromtrnS-GCU located on the opposite DNA strand. S1 mapping and primer extension experiments showed that these multiple transcripts comprise eight distinct 5′ ends. By in vitro capping assays two of them were determined to be transcriptional initiation sites; one is located 163 bp upstream ofpsbKand the other is 6 bp upstream oftrnG. The 3′ ends of transcripts were determined by S1 mapping; one lies betweenpsbIandtrnGand the other is at the end oftrnG. The presence of dual promoters oftrnGis discussed.