Department of Microbiology, Miami Universitygrid.259956.4, Oxford, Ohio, USA.
J Bacteriol. 2022 Jun 21;204(6):e0003222. doi: 10.1128/jb.00032-22. Epub 2022 May 23.
The opportunistic pathogen A. baumannii has a remarkable capacity to persist in the hospital environment and cause devastating human infections. This capacity can be attributed partly to the sensing and regulatory systems that enable this pathogen to modify its physiology based on environmental cues. One of the signals that A. baumannii senses and responds to is light through the sensing and regulatory roles of the BlsA photoreceptor protein in cells cultured at temperatures below 30°C. This report presents evidence that a light stimulon is operational at 37°C, a condition at which the BlsA production and activity are drastically impaired. Global transcriptional analysis showed that the 37°C light stimulon includes the differential expression of chromosomal genes encoding a wide range of functions that are known to be involved in the adaptation to different metabolic conditions, as well as virulence and persistence in the host and the medical environment. Unexpectedly, the 37°C light stimulon also includes the differential expression of conjugation functions encoded by pAB3 plasmid genes. Our work further demonstrates that the TetR1 and H-NS regulators encoded by this conjugative plasmid control the expression of HO resistance and surface motility, respectively. Furthermore, our data showed that pAB3 has an overall negative effect on the expression of these phenotypes and plays no significant virulence role. Although the nature of the bacterial factors and the mechanisms by which the regulation is attained at 37°C remain unknown, taken together, our work expands the current knowledge about light sensing and gene regulation in A. baumannii. As a facultative pathogen, Acinetobacter baumannii persists in various environments by sensing different environmental cues, including light. This report provides evidence of light-dependent regulation at 37°C of the expression of genes coding for a wide range of functions, including those involved in the conjugation of the pAB3 plasmid. Although this plasmid affects the expression of virulence traits when tested under laboratory conditions, it does not have a significant impact when tested using and experimental models. These findings provide a better understanding of the interplay between light regulation and plasmid persistence in the pathobiology of A. baumannii.
机会性病原体鲍曼不动杆菌具有在医院环境中持续存在并引起严重人体感染的非凡能力。这种能力部分归因于感应和调节系统，使这种病原体能够根据环境线索改变其生理学。鲍曼不动杆菌感应和响应的信号之一是光，这是通过细胞中 BlsA 光受体蛋白在低于 30°C 的温度下培养时的感应和调节作用来实现的。本报告提供的证据表明，在 37°C 时存在光刺激物，而 BlsA 的产生和活性在该条件下严重受损。全转录组分析表明，37°C 光刺激物包括染色体基因的差异表达，这些基因编码广泛的功能，已知这些功能参与适应不同代谢条件以及在宿主和医疗环境中的毒力和持久性。出乎意料的是，37°C 光刺激物还包括 pAB3 质粒基因编码的接合功能的差异表达。我们的工作进一步表明，该可接合质粒编码的 TetR1 和 H-NS 调节剂分别控制 HO 抗性和表面运动性的表达。此外，我们的数据表明，pAB3 对这些表型的表达有整体负效应，并且没有发挥重要的毒力作用。尽管细菌因子的性质和在 37°C 下获得调节的机制尚不清楚，但总的来说，我们的工作扩展了关于鲍曼不动杆菌中光感应和基因调节的现有知识。作为一种兼性病原体，鲍曼不动杆菌通过感应包括光在内的各种环境线索在各种环境中持续存在。本报告提供了在 37°C 时依赖光调节表达编码广泛功能的基因的证据，这些功能包括与 pAB3 质粒接合相关的基因。虽然在实验室条件下测试时，该质粒会影响毒力性状的表达，但在使用 和 实验模型测试时，它没有显著影响。这些发现提供了对鲍曼不动杆菌病生物学中光调节和质粒持续存在之间相互作用的更好理解。
