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首页> 外文期刊>Journal of bacteriology >Joint Transcriptional Control of xpsR, the Unusual Signal Integrator of the Ralstonia solanacearum Virulence Gene Regulatory Network, by a Response Regulator and a LysR-Type Transcriptional Activator
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Joint Transcriptional Control of xpsR, the Unusual Signal Integrator of the Ralstonia solanacearum Virulence Gene Regulatory Network, by a Response Regulator and a LysR-Type Transcriptional Activator

机译：xpsR，青枯雷尔氏菌毒力基因调控网络的异常信号整合者，由响应调节剂和LysR型转录激活因子联合转录控制。

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摘要

Ralstonia (Pseudomonas)solanacearum is a soil-borne phytopathogen that causes a wilting disease of many important crops. It makes large amounts of the exopolysaccharide EPS I, which it requires for efficient colonization, wilting, and killing of plants. Transcription of the epsoperon, encoding biosynthetic enzymes for EPS I, is controlled by a unique and complex sensory network that responds to multiple environmental signals. This network is comprised of the novel transcriptional activator XpsR, three distinct two-component regulatory systems (VsrAD, VsrBC, and PhcSR), and the LysR-type regulator PhcA, which is under the control of PhcSR. Here we show that thexpsR promoter (PxpsR) is simultaneously controlled by PhcA and VsrD, permitting XpsR to act like a signal integrator, simultaneously coordinating signal input into theeps promoter from both VsrAD and PhcSR. Additionally, we used in vivo expression analysis and in vitro DNA binding assays with substitution and deletion mutants of PxpsR to show the following. (i) PhcA primarily interacts with a typical 14-bp LysR-type consensus sequence around position ?77, causing a sixfold activation of PxpsR; a weaker, less-defined binding site between ?183 and ?239 likely enhances PhcA binding and activation via the ?77 site another twofold. (ii) Full 70-fold activation of PxpsR requires the additional interaction of the VsrD response regulator (or its surrogate) with a 14-bp dyadic sequence centered around ?315 where it enhances activation (and possibly binding) by PhcA; however, VsrD alone cannot activate PxpsR. (iii) Increasing the distance between the putative VsrD binding site from that of PhcA by up to 232 bp did not dramatically affect PxpsR activation or regulation.
机译： Ralstonia （ Pseudomonas ） solanacearum 是一种土壤传播的植物病原体，可导致许多重要农作物萎。它会产生大量的胞外多糖EPS I，这是有效定植，枯萎和杀死植物所必需的。编码EPS I生物合成酶的 eps 操纵子的转录受一个独特且复杂的传感网络控制，该传感网络可响应多种环境信号。该网络由新型转录激活因子XpsR，三个不同的两组分调节系统（VsrAD，VsrBC和PhcSR）和LysR型调节剂PhcA组成，后者在PhcSR的控制下。在这里我们显示 xpsR 启动子（P xpsR ）同时受PhcA和VsrD的控制，从而允许XpsR同时充当信号积分器协调信号从VsrAD和PhcSR输入到 eps 启动子。此外，我们使用体内表达分析和体外DNA结合测定法以及P xpsR 的取代和缺失突变体来显示以下内容。 （i）PhcA主要与第77位的典型14 bp LysR型共有序列相互作用，引起P xpsR 的六倍活化;在？183和？239之间较弱，定义较不明确的结合位点可能会通过另外的？77位点增强PhcA结合和激活。 （ii）P xpsR 的全部70倍激活需要VsrD反应调节剂（或其替代物）与以315为中心的14 bp二进序列进行额外的相互作用它增强了PhcA的激活作用（并可能结合）;但是，仅VsrD不能激活P xpsR 。 （iii）假定的VsrD结合位点与PhcA的结合位点之间的距离最多增加232 bp，并没有显着影响P xpsR 的激活或调节。

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