Transcriptional pausing in the Bacillus subtilis pyr operon in vitro: a role in transcriptional attenuation?
Transcriptional pausing in the Bacillus subtilis pyr operon in vitro: a role in transcriptional attenuation?
复制标题
体外枯草芽孢杆菌pyr操纵子中的转录暂停：在转录减弱中的作用？
DOI：
10.1128/jb.185.16.4764-4771.2003
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发表时间：
2003
影响因子：
3.2
通讯作者：
Switzer,RobertL
中科院分区：
文献类型：
--
作者：
Zhang,Hesheng;Switzer,RobertL
The genes encoding the enzymes of pyrimidine nucleotide biosynthesis (pyrgenes) are regulated inBacillus subtilisand many other bacterial species by transcriptional attenuation. When UMP or UTP is bound to the PyrR regulatory protein, it binds topyrmRNA at specific sequences and secondary structures in the RNA. Binding to this site prevents formation of an antiterminator stem-loop in the RNA and permits formation of a downstream terminator, leading to reduced expression of thepyrgenes lying downstream from the terminator. The functioning of several other transcriptional attenuation systems has been shown to involve transcriptional pausing; this observation stimulated us to use single-round transcription ofpyrgenes to test for formation of paused transcripts in vitro. Using templates with each of the three knownB. subtilis pyrattenuation sites, we identified one major pause site in each in which the half-life of the paused transcript was increased four- to sixfold by NusA. In each case pausing at the NusA-stimulated site prevented formation of a complete antiterminator stem-loop, while it resulted in increased time for a PyrR binding loop to form and for PyrR to bind to this loop. Thus, the pausing detected in vitro is potentially capable of playing a role in establishing the correct timing forpyrattenuation in vivo. With two of threepyrtemplates the combination of NusA with PyrR markedly stimulated termination of transcription at the normal termination sites. This suggests that NusA, by stabilizing pausing, plays a role in termination ofpyrtranscription in vivo.
