Formation of intermediate transcription initiation complexes at pfliD and pflgM by sigma(28) RNA polymerase.
Formation of intermediate transcription initiation complexes at pfliD and pflgM by sigma(28) RNA polymerase.
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通过 sigma(28) RNA 聚合酶在 pfliD 和 pflgM 处形成中间转录起始复合物。
DOI：
10.1128/jb.183.21.6244-6252.2001
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发表时间：
2001
影响因子：
3.2
通讯作者：
Dombroski,AJ
中科院分区：
文献类型：
--
作者：
Givens,JR;McGovern,CL;Dombroski,AJ
原核生物RNA聚合酶的α亚基是控制转录起始的重要因子。初级生长因子对生长至关重要，而替代生长因子则在各种刺激下被激活。鼠伤寒沙门氏菌鞭毛生物合成过程中3类基因的表达依赖于替代性转录因子β 28。以前，提出了一种新的机制，转录起始在thefliC启动子的p28全酶。在这里，我们已经表征了在fliD和flgM启动子处携带p28的全酶的转录起始机制，以确定在pfliC处观察到的起始机制是否是所有p28依赖性启动子的普遍现象。温度依赖性足迹法表明，启动子结合特性和低温开放复合物的形成是相似的pfliC，pfliD，和pflgM。然而，DNA链分离和复合物稳定性的某些方面是启动子依赖性的。在pflgM处以协调一致的方式形成开放复合物，而在pfliD处发生开放复合物形成的顺序模式。由全酶携带的pFlgM形成的开放和引发的复合物通常对肝素挑战不稳定，除了在pFlgM处引发的复合物，其在核苷三磷酸存在下是稳定的。
The ς subunit of prokaryotic RNA polymerase is an important factor in the control of transcription initiation. Primary ς factors are essential for growth, while alternative ς factors are activated in response to various stimuli. Expression of class 3 genes during flagellum biosynthesis inSalmonella entericaserovar Typhimurium is dependent on the alternative ς factor ς28. Previously, a novel mechanism of transcription initiation at thefliCpromoter by ς28holoenzyme was proposed. Here, we have characterized the mechanism of transcription initiation by a holoenzyme carrying ς28at thefliDandflgMpromoters to determine if the mechanism of initiation observed at pfliCis a general phenomenon for all ς28-dependent promoters. Temperature-dependent footprinting demonstrated that promoter binding properties and low-temperature open complex formation are similar for pfliC, pfliD, and pflgM. However, certain aspects of DNA strand separation and complex stability are promoter dependent. Open complexes form in a concerted manner at pflgM, while a sequential pattern of open complex formation occurs at pfliD. Open and initiated complexes formed by holoenzyme carrying ς28are generally unstable to heparin challenge, with the exception of initiated complexes at pflgM, which are stable in the presence of nucleoside triphosphates.