BadR (BB0693) controls growth phase-dependent induction of rpoS and bosR in Borrelia burgdorferi via recognizing TAAAATAT motifs
BadR (BB0693) controls growth phase-dependent induction of rpoS and bosR in Borrelia burgdorferi via recognizing TAAAATAT motifs
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DOI：
10.1111/mmi.13206
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发表时间：
2015-12-01
影响因子：
3.6
通讯作者：
Zhou, Jianli
中科院分区：
文献类型：
--
作者：
Ouyang, Zhiming;Zhou, Jianli
在伯氏疏螺旋体（Bb）中，替代性σ因子RpoS在Bb适应蜱和哺乳动物期间起核心作用。以前的研究表明，RpoS不表达在螺旋体生长的早期阶段，或当Bb驻留在蜱在蜕皮期，但这些事件的分子细节仍然未知。在目前的研究中，rpoS启动子结合蛋白的生物磁珠分离，加上遗传失活，被用来确定BadR（BB 0693）作为一个负调节器，控制生长阶段依赖性诱导的rpoS和bosR在Bb。当badR失活时，rpoS和bosR的表达仅在细菌生长的早期阶段被诱导，而不是在稳定生长期。重组BadR通过富含AT的TAAAATAT基序与rpoS的启动子DNA和bosR上游的调控区结合。该基序中的突变显著抑制或消除rBadR结合。这些结果表明BadR直接影响Bb中rpoS和bosR的表达。BadR在Bb生命周期的关键时刻微调RpoN-RpoS通路激活的这种新认识的作用可能代表了对sigma（54）依赖性基因调控的另一层基因控制。
In Borrelia burgdorferi (Bb), the alternative sigma factor RpoS plays a central role during Bb's adaptation to ticks and mammals. Previous studies have demonstrated that RpoS is not expressed during the early stages of spirochetal growth or when Bb resides in ticks during the intermolt phase, but the molecular details of these events remain unknown. In the current study, biomagnetic bead separation of rpoS promoter-binding proteins, coupled with genetic inactivation, was employed to identify BadR (BB0693) as a negative regulator that controls growth phase-dependent induction of rpoS and bosR in Bb. When badR was inactivated, the expression of rpoS and bosR was induced only during the early stages of bacterial growth, but not during the stationary growth phase. Recombinant BadR bound to the promoter DNA of rpoS and the regulatory region upstream of bosR via AT-rich TAAAATAT motifs. Mutations in this motif markedly inhibited or abolished rBadR binding. These results suggest that BadR directly influences the expression of both rpoS and bosR in Bb. This newly recognized role for BadR to fine-tune the activation of the RpoN-RpoS pathway at strategic times in Bb's life cycle potentially represents another layer of gene control over sigma(54)-dependent gene regulation.