Esyunina Daria, Klimuk Evgeny, Severinov Konstantin, Kulbachinskiy Andrey
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia;
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia; Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia; and.
Proc Natl Acad Sci U S A. 2015 Feb 17;112(7):2017-22. doi: 10.1073/pnas.1416330112. Epub 2015 Feb 2.
Transcription antitermination is a common strategy of gene expression regulation, but only a few transcription antitermination factors have been studied in detail. Here, we dissect the transcription antitermination mechanism of Xanthomonas oryzae virus Xp10 protein p7, which binds host RNA polymerase (RNAP) and regulates both transcription initiation and termination. We show that p7 suppresses intrinsic termination by decreasing RNAP pausing and increasing the transcription complex stability, in cooperation with host-encoded factor NusA. Uniquely, the antitermination activity of p7 depends on the ω subunit of the RNAP core and is modulated by ppGpp. In contrast, the inhibition of transcription initiation by p7 does not require ω but depends on other RNAP sites. Our results suggest that p7, a bifunctional transcription factor, uses distinct mechanisms to control different steps of transcription. We propose that regulatory functions of the ω subunit revealed by our analysis may extend to its homologs in eukaryotic RNAPs.
转录抗终止是基因表达调控的一种常见策略，但只有少数转录抗终止因子得到了详细研究。在此，我们剖析了水稻黄单胞菌病毒Xp10蛋白p7的转录抗终止机制，该蛋白与宿主RNA聚合酶（RNAP）结合并调控转录起始和终止。我们发现，p7与宿主编码因子NusA协同作用，通过减少RNAP暂停和增加转录复合物稳定性来抑制内在终止。独特的是，p7的抗终止活性依赖于RNAP核心的ω亚基，并受ppGpp调节。相比之下，p7对转录起始的抑制不依赖于ω，而是依赖于其他RNAP位点。我们的结果表明，双功能转录因子p7利用不同机制控制转录的不同步骤。我们提出，我们分析中揭示的ω亚基的调控功能可能扩展到其在真核RNAP中的同源物。
