A Light-Regulated Type I Pilus Contributes to Acinetobacter baumannii Biofilm, Motility, and Virulence Functions.
A Light-Regulated Type I Pilus Contributes to Acinetobacter baumannii Biofilm, Motility, and Virulence Functions.
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光调节的 I 型菌毛有助于鲍曼不动杆菌生物膜、运动性和毒力功能。
DOI：
10.1128/iai.00442-18
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发表时间：
2018
影响因子：
3.1
通讯作者：
Actis,LuisA
中科院分区：
文献类型：
--
作者：
Wood,CecilyR;Ohneck,EmilyJ;Edelmann,RichardE;Actis,LuisA
鲍曼不动杆菌ATCC 17978的转录分析表明，在24°C黑暗培养的细胞中，A1S_2091的表达通过依赖于BlsA光感受器的过程增强。A1S_2091是A1S_2088-A1S_2091多顺反子操纵子的一个组成部分，被预测编码I型伴侣/usher菌毛组装系统，破坏A1S_2091会破坏塑料表面的运动和膜的形成，但在黑暗中培养的细菌会显著增强塑料上生物膜的形成。基于这些观察结果，A1S_2088-A1S_2091操纵子被命名为光调节菌毛ABCD （prpABCD）操纵子，其中A1S_2091编码PrpA蛋白亚基。出乎意料的是，在37°C培养的ATCC 17978和prpa2等基因突变细胞的比较分析显示，在温度条件下，光调节生物膜的生物发生和运动功能的表达极大地影响了BlsA的产生及其光感活性。这些实验还表明，ATCC 17978细胞产生可替代的光调节黏附素和/或菌毛系统，在24°C和37°C的塑料和极化A549肺泡上皮细胞表面增强细菌黏附和生物膜的形成，其中细菌细丝和细胞链的形成显着增强。当使用mellonella毒力模型进行测试时，prpa的失活也导致毒力显著降低。所有这些观察结果都提供了强有力的证据，表明鲍曼不动杆菌有能力感知光，并利用未确定的替代感知和调节系统，以及替代粘附和运动细胞功能，与生物和非生物表面相互作用，从而使这种病原体能够在不同的生态位中持续存在。
Transcriptional analyses of Acinetobacter baumannii ATCC 17978 showed that the expression of A1S_2091 was enhanced in cells cultured in darkness at 24°C through a process that depended on the BlsA photoreceptor. Disruption of A1S_2091, a component of the A1S_2088-A1S_2091 polycistronic operon predicted to code for a type I chaperone/usher pilus assembly system, abolished surface motility and pellicle formation but significantly enhanced biofilm formation on plastic by bacteria cultured in darkness. Based on these observations, the A1S_2088-A1S_2091 operon was named thephotoregulatedpilus ABCD (prpABCD) operon, with A1S_2091 coding for the PrpA pilin subunit. Unexpectedly, comparative analyses of ATCC 17978 andprpAisogenic mutant cells cultured at 37°C showed the expression of light-regulated biofilm biogenesis and motility functions under a temperature condition that drastically affects BlsA production and its light-sensing activity. These assays also suggest that ATCC 17978 cells produce alternative light-regulated adhesins and/or pilus systems that enhance bacterial adhesion and biofilm formation at both 24°C and 37°C on plastic as well as on the surface of polarized A549 alveolar epithelial cells, where the formation of bacterial filaments and cell chains was significantly enhanced. The inactivation ofprpAalso resulted in a significant reduction in virulence when tested by using the Galleria mellonella virulence model. All these observations provide strong evidence showing the capacity of A. baumannii to sense light and interact with biotic and abiotic surfaces using undetermined alternative sensing and regulatory systems as well as alternative adherence and motility cellular functions that allow this pathogen to persist in different ecological niches.