An unconventional RNA-based thermosensor within the 5′ UTR of Staphylococcus aureus cidA
An unconventional RNA-based thermosensor within the 5′ UTR of Staphylococcus aureus cidA
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DOI：
10.1371/journal.pone.0214521
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发表时间：
2019-04-01
期刊：
影响因子：
3.7
通讯作者：
Murphy, Erin R.
中科院分区：
文献类型：
--
作者：
Hussein, Hebaallaha;Fris, Megan E.;Murphy, Erin R.
金黄色葡萄球菌是一种全球关注的革兰氏阳性细菌病原体，也是世界范围内细菌感染的主要原因。无症状携带金黄色葡萄球菌在皮肤和鼻腔前部是常见的，并被认为是侵袭性感染的诱发因素。金黄色葡萄球菌从携带状态向侵袭性感染状态的转变通常伴随着温度从大约33摄氏度上升到37摄氏度，这种温度变化在其他病原体中已知会影响基因表达，通常导致促进宿主生存或毒力的因子的产生增加。细菌根据温度调节基因表达的一种机制是通过基于rna的温度传感器的调节活性，即控制翻译效率的顺式核糖体调节剂。本研究旨在鉴定和表征金黄色葡萄球菌中基于rna的热传感器。最初通过对金黄色葡萄球菌USA300基因组的计算机分析预测，基于记者的基因表达分析和位点特异性诱变进行了研究，以证明在cidA的5' UTR中存在一个功能性的热传感器，该基因与生物膜的形成和病原体的存活有关。组成已鉴定的热传感器的核酸序列足以赋予温度依赖的转录后调控，并且通过引入旨在稳定或破坏已鉴定的热传感器结构的位点特异性突变，可预测地改变活性。所鉴定的调节因子在原生细菌宿主金黄色葡萄球菌和远端相关物种大肠杆菌中都起作用，表明其调节活性独立于宿主特异性因子。有趣的是，与迄今为止表征的大多数基于细菌rna的热传感器不同，cidA热传感器有助于在较低温度下增加靶基因的表达。除了在重要的病原菌金黄色葡萄球菌中首次对基于rna的热传感器进行表征外，它还强调了这类重要的核糖调节因子的功能多样性。
Staphylococcus aureus is a Gram-positive bacterial pathogen of global concern and a leading cause of bacterial infections worldwide. Asymptomatic carriage of S. aureus on the skin and in the anterior nares is common and recognized as a predisposing factor to invasive infection. Transition of S. aureus from the carriage state to that of invasive infection is often accompanied by a temperature upshift from approximately 33 degrees C to 37 degrees C. Such a temperature shift is known in other pathogens to influence gene expression, often resulting in increased production of factors that promote survival or virulence within the host. One mechanism by which bacteria modulate gene expression in response to temperature is by the regulatory activity of RNA-based thermosensors, cis-acting riboregulators that control translation efficiency. This study was designed to identify and characterize RNA-based thermosensors in S. aureus. Initially predicted by in silico analyses of the S. aureus USA300 genome, reporter-based gene expression analyses and site-specific mutagenesis were performed to demonstrate the presence of a functional thermosensor within the 5' UTR of cidA, a gene implicated in biofilm formation and survival of the pathogen. The nucleic sequence composing the identified thermosensor are sufficient to confer temperature-dependent post-transcriptional regulation, and activity is predictably altered by the introduction of site-specific mutations designed to stabilize or destabilize the structure within the identified thermosensor. The identified regulator is functional in both the native bacterial host S. aureus and in the distally related species Escherichia coli, suggesting that its regulatory activity is independent of host-specific factors. Interestingly, unlike the majority of bacterial RNA-based thermosensors characterized to date, the cidA thermosensor facilitates increased target gene expression at lower temperatures. In addition to the characterization of the first RNA-based thermosensor in the significant pathogen S. aureus, it highlights the diversity of function within this important class of ribo-regulators.