School of Biological Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, M13 9PT, UK.
Nanjing Medical University, School, 140 Hanzhong Road, Nanjing, 210029, China.
Sci Rep. 2017 Dec 20;7(1):17924. doi: 10.1038/s41598-017-17891-0.
In this study we characterise three tandem promoters (PR1-1, PR1-2 and PR1-3) within the PR1 regulatory region of the Escherichia coli kps capsule gene cluster. Transcription from promoter PR1-2 was dependent on the activity of the upstream promoter PR1-1, which activated PR1-2 via transcription coupled DNA supercoiling. During growth at 37 °C a temporal pattern of transcription from all three promoters was observed with maximum transcriptional activity evident during mid-exponential phase followed by a sharp decrease in activity as the cells enter stationary phase. The growth phase dependent transcription was regulated by Integration Host Factor (IHF), which bound within the PR1 region to repress transcription from PR1-2 and PR1-3. This pattern of transcription was mirrored by growth phase dependent expression of the K1 capsule. Overall these data reveal a complex pattern of transcriptional regulation for an important virulence factor with IHF playing a role in regulating growth phase expression.
在这项研究中,我们描述了大肠杆菌 kps 荚膜基因簇 PR1 调节区中的三个串联启动子(PR1-1、PR1-2 和 PR1-3)。启动子 PR1-2 的转录依赖于上游启动子 PR1-1 的活性,PR1-1 通过转录偶联的 DNA 超螺旋化激活 PR1-2。在 37°C 下生长时,观察到所有三个启动子的转录存在时间模式,在指数中期表现出最大的转录活性,随后随着细胞进入静止期,活性急剧下降。这种生长阶段依赖性转录受整合宿主因子 (IHF) 的调节,IHF 在 PR1 区域内结合,抑制 PR1-2 和 PR1-3 的转录。这种转录模式与 K1 荚膜的生长阶段依赖性表达相呼应。总的来说,这些数据揭示了一个重要毒力因子的复杂转录调控模式,IHF 在调节生长阶段表达中发挥作用。