Instituto de Bionanotecnología del NOA (INBIONATEC-CONICET), Universidad Nacional de Santiago del Estero (UNSE), Santiago del Estero, Argentina.
Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario (UNR), Rosario, Argentina.
PLoS One. 2022 Apr 20;17(4):e0254291. doi: 10.1371/journal.pone.0254291. eCollection 2022.
Acinetobacter nosocomialis is a Gram-negative opportunistic pathogen, whose ability to cause disease in humans is well recognized. Blue light has been shown to modulate important physiological traits related to persistence and virulence in this microorganism. In this work, we characterized the three Blue Light sensing Using FAD (BLUF) domain-containing proteins encoded in the A. nosocomialis genome, which account for the only canonical light sensors present in this microorganism. By focusing on a light-modulated bacterial process such as motility, the temperature dependence of light regulation was studied, as well as the expression pattern and spectroscopic characteristics of the different A. nosocomialis BLUFs. Our results show that the BLUF-containing proteins AnBLUF65 and AnBLUF46 encode active photoreceptors in the light-regulatory temperature range when expressed recombinantly. In fact, AnBLUF65 is an active photoreceptor in the temperature range from 15°C to 37°C, while AnBLUF46 between 15°C to 32°C, in vitro. In vivo, only the Acinetobacter baumannii BlsA's ortholog AnBLUF65 was expressed in A. nosocomialis cells recovered from motility plates. Moreover, complementation assays showed that AnBLUF65 is able to mediate light regulation of motility in A. baumannii ΔblsA strain at 30°C, confirming its role as photoreceptor and in modulation of motility by light. Intra-protein interactions analyzed using 3D models built based on A. baumannii´s BlsA photoreceptor, show that hydrophobic/aromatic intra-protein interactions may contribute to the stability of dark/light- adapted states of the studied proteins, reinforcing the previous notion on the importance of these interactions in BLUF photoreceptors. Overall, the results presented here reveal the presence of BLUF photoreceptors in A. nosocomialis with idiosyncratic characteristics respect to the previously characterized A. baumannii's BlsA, both regarding the photoactivity temperature-dependency as well as expression patterns, contributing thus to broaden our knowledge on the BLUF family.
鲍曼不动杆菌是一种革兰氏阴性机会致病菌，其在人类中引起疾病的能力已得到充分认识。已证明蓝光能够调节与该微生物的持久性和毒力相关的重要生理特征。在这项工作中，我们对鲍曼不动杆菌基因组中编码的三种含 BLUF 结构域的蓝光传感蛋白（BLUF）进行了表征，这些蛋白是该微生物中唯一的典型光传感器。通过聚焦于运动等受光调节的细菌过程，研究了光调节的温度依赖性，以及不同鲍曼不动杆菌 BLUF 的表达模式和光谱特征。我们的结果表明，当在重组体中表达时，含 BLUF 的蛋白 AnBLUF65 和 AnBLUF46 编码在光调节温度范围内具有活性的光受体。实际上，AnBLUF65 在 15°C 至 37°C 的温度范围内是一种活性光受体，而 AnBLUF46 在 15°C 至 32°C 的温度范围内是一种活性光受体，在体外。在体内，仅鲍曼不动杆菌的 BlsA 同源物 AnBLUF65 在从运动平板中回收的鲍曼不动杆菌细胞中表达。此外，互补测定表明，AnBLUF65 能够在 30°C 下介导鲍曼不动杆菌ΔblsA 菌株的运动的光调节，证实了其作为光受体和通过光调节运动的作用。使用基于鲍曼不动杆菌 BlsA 光受体构建的 3D 模型分析的蛋白内相互作用表明，疏水性/芳香性蛋白内相互作用可能有助于研究蛋白的黑暗/光适应状态的稳定性，这加强了先前关于 BLUF 光受体中这些相互作用重要性的观点。总体而言，这里呈现的结果揭示了鲍曼不动杆菌中 BLUF 光受体的存在，这些光受体具有与先前表征的鲍曼不动杆菌的 BlsA 不同的特征，无论是在光活性温度依赖性还是表达模式方面，这有助于拓宽我们对 BLUF 家族的认识。
