Hyde Jenny A, Trzeciakowski Jerome P, Skare Jonathan T
Department of Microbial and Molecular Pathogenesis, Texas A&M Health Science Center, College Station, TX 77843-1114, USA.
J Bacteriol. 2007 Jan;189(2):437-45. doi: 10.1128/JB.01109-06. Epub 2006 Nov 10.
The etiologic agent of Lyme disease, Borrelia burgdorferi, must adapt to the distinct environments of its arthropod vector and mammalian host during its complex life cycle. B. burgdorferi alters gene expression and protein synthesis in response to temperature, pH, and other uncharacterized environmental factors. The hypothesis tested in this study is that dissolved gases, including CO(2), serve as a signal for B. burgdorferi to alter protein production and gene expression. In this study we focused on characterization of in vitro anaerobic (5% CO(2), 3% H(2), 0.087 ppm O(2)) and microaerophilic (1% CO(2), 3.48 ppm O(2)) growth conditions and how they modulate protein synthesis and gene expression in B. burgdorferi. Higher levels of several immunoreactive proteins, including BosR, NapA, DbpA, OspC, BBK32, and RpoS, were synthesized under anaerobic conditions. Previous studies demonstrated that lower levels of NapA were produced when microaerophilic cultures were purged with nitrogen gas to displace oxygen and CO(2). In this study we identified CO(2) as a factor contributing to the observed change in NapA synthesis. Specifically, a reduction in the level of dissolved CO(2), independent of O(2) levels, resulted in reduced NapA synthesis. BosR, DbpA, OspC, and RpoS synthesis was also decreased with the displacement of CO(2). Quantitative reverse transcription-PCR indicated that the levels of the dbpA, ospC, and BBK32 transcripts are increased in the presence of CO(2), indicating that these putative borrelial virulence determinants are regulated at the transcriptional level. Thus, dissolved CO(2) may be an additional cue for borrelial host adaptation and gene regulation.
莱姆病的病原体伯氏疏螺旋体在其复杂的生命周期中必须适应节肢动物媒介和哺乳动物宿主的不同环境。伯氏疏螺旋体响应温度、pH值和其他未明确的环境因素而改变基因表达和蛋白质合成。本研究检验的假设是，包括二氧化碳在内的溶解气体作为一种信号，促使伯氏疏螺旋体改变蛋白质产生和基因表达。在本研究中，我们着重于体外厌氧（5%二氧化碳、3%氢气、0.087 ppm氧气）和微需氧（1%二氧化碳、3.48 ppm氧气）生长条件的特性，以及它们如何调节伯氏疏螺旋体中的蛋白质合成和基因表达。在厌氧条件下合成了几种免疫反应性较高的蛋白质，包括BosR、NapA、DbpA、OspC、BBK32和RpoS。先前的研究表明，当用氮气吹扫微需氧培养物以置换氧气和二氧化碳时，NapA的产生水平较低。在本研究中，我们确定二氧化碳是导致观察到的NapA合成变化的一个因素。具体而言，溶解二氧化碳水平的降低（与氧气水平无关）导致NapA合成减少。随着二氧化碳的置换，BosR、DbpA、OspC和RpoS的合成也减少。定量逆转录PCR表明，在有二氧化碳存在的情况下，dbpA、ospC和BBK32转录本的水平升高，表明这些假定的疏螺旋体毒力决定因素在转录水平受到调控。因此，溶解的二氧化碳可能是疏螺旋体适应宿主和基因调控的另一个线索。
