Transcriptional and posttranscriptional control of mRNA from lrtA, a light-repressed transcript in Synechococcus sp. PCC 7002.
Transcriptional and posttranscriptional control of mRNA from lrtA, a light-repressed transcript in Synechococcus sp. PCC 7002.
复制标题
lrtA mRNA 的转录和转录后控制，lrtA 是聚球藻中的光抑制转录物。
DOI：
10.1104/pp.117.1.225
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发表时间：
1998
期刊：
影响因子：
7.4
通讯作者：
Widger,WR
中科院分区：
文献类型：
--
作者：
Samartzidou,H;Widger,WR
蓝细菌集球藻lrtA的转录调控和转录稳定性研究使用核糖核酸酶保护测定法研究PCC 7002。在连续照射的细胞中没有检测到lrtA的转录物，但是当细胞置于黑暗中时，转录物水平增加。在将细胞置于黑暗中后，在该转录物的积累中观察到20至30分钟的滞后。转录物合成在黑暗中持续3小时，并且转录物水平保持升高至少7小时。暗适应前加入10 μm利福平可抑制暗条件下flrtA的转录。在向3小时暗适应细胞中加入利福平后，lrtA转录物水平保持恒定30分钟并持续3小时。在黑暗中估计半衰期为3小时，而在光照下观察到半衰期为4分钟。预测了该转录本在5′非翻译区内的广泛二级结构，该转录本也存在于来自不同蓝细菌集胞藻的flrtA的5′非翻译区中。PCC 6803。有证据表明lrtA转录物的稳定性不是由核糖核酸酶活性从暗到亮的差异引起的。加入25 μg mL− 1氯霉素后，在照射的细胞中检测到少量的flrtA转录物。在光照前向暗适应细胞中加入氯霉素允许相对于不含氯霉素的对照在光照下检测thelrtA转录物更长的时间。这些结果表明，lrtA mRNA的加工在光下是不同的，在黑暗中，和蛋白质合成所需的光抑制的lrtA转录。
Transcription regulation and transcript stability of a light-repressed transcript,lrtA, from the cyanobacteriumSynechococcussp. PCC 7002 were studied using ribonuclease protection assays. The transcript forlrtA was not detected in continuously illuminated cells, yet transcript levels increased when cells were placed in the dark. A lag of 20 to 30 min was seen in the accumulation of this transcript after the cells were placed in the dark. Transcript synthesis continued in the dark for 3 h and the transcript levels remained elevated for at least 7 h. The addition of 10 μm rifampicin to illuminated cells before dark adaptation inhibited the transcription oflrtA in the dark. Upon the addition of rifampicin to 3-h dark-adapted cells,lrtA transcript levels remained constant for 30 min and persisted for 3 h. A 3-h half-life was estimated in the dark, whereas a 4-min half-life was observed in the light. Extensive secondary structure was predicted for this transcript within the 5′ untranslated region, which is also present in the 5′ untranslated region oflrtA from a different cyanobacterium,Synechocystissp. PCC 6803. Evidence suggests thatlrtA transcript stability is not the result of differences in ribonuclease activity from dark to light. Small amounts oflrtA transcript were detected in illuminated cells upon the addition of 25 μg mL−1chloramphenicol. The addition of chloramphenicol to dark-adapted cells before illumination allowed detection of thelrtA transcript for longer times in the light relative to controls without chloramphenicol. These results suggest thatlrtA mRNA processing in the light is different from that in the dark and that protein synthesis is required for light repression of thelrtA transcript.