海洋细菌费氏弧菌引发其鱿鱼宿主的共生定植,Euprymnascolopes,通过从依赖于共生多糖基因座(syp)的生物膜形成和分散。历史上,费氏弧菌的遗传操作需要可视化syp依赖性生物膜的形成在体外,但是最近,我们发现两个小分子的结合,对氨基苯甲酸(PABA)和钙,足以诱导野生型菌株ES114形成生物膜。这里,我们确定这些依赖syp的生物膜依赖于syp阳性调节因子RscS,因为这种感应激酶的丢失废除了生物膜的形成和syp转录。这些结果特别值得注意,因为RscS的损失,一个关键的殖民因素,在其他遗传和培养基条件下对生物膜形成几乎没有影响。生物膜缺陷可以通过野生型RscS和RscS嵌合体来补充,该嵌合体包含与SypF的C端HPT结构域融合的RscS的N端结构域,下游传感器激酶。它不能补充缺乏周质感觉结构域或在磷酸化保守位点含有突变的衍生物,H412,表明这些线索通过RscS促进信号传导。最后,当将rscS引入异源系统时,pABA和/或钙能够诱导生物膜形成。一起来看,这些数据表明RscS负责识别pABA和钙,或者这些线索的下游后果,诱导生物膜形成。因此,这项研究提供了对促进费氏弧菌生物膜形成的信号和调节剂的见解。重要性细菌生物膜在各种环境中是常见的。众所周知,由于生物膜对抗生素的内在抗性,在人体内形成的感染性生物膜难以治疗。细菌必须整合来自环境的信号来构建和维持生物膜,并且经常使用感应外部信号的传感器激酶,它触发信号级联以引发响应。然而,识别激酶感知的信号仍然是一个具有挑战性的研究领域。这里,我们确定混合传感器激酶,RscS,对于费氏弧菌识别对氨基苯甲酸和钙作为诱导生物膜形成的线索至关重要。因此,这项研究提高了我们对导致生物膜形成的信号转导途径的理解。
The marine bacterium Vibrio fischeri initiates symbiotic colonization of its squid host, Euprymna scolopes, by forming and dispersing from a biofilm dependent on the symbiosis polysaccharide locus (syp). Historically, genetic manipulation of V. fischeri was needed to visualize syp-dependent biofilm formation in vitro, but recently, we discovered that the combination of two small molecules, para-aminobenzoic acid (
pABA) and calcium, was sufficient to induce wild-type strain ES114 to form biofilms. Here, we determined that these syp-dependent biofilms were reliant on the positive syp regulator RscS, since the loss of this sensor kinase abrogated biofilm formation and syp transcription. These results were of particular note because loss of RscS, a key colonization factor, exerts little to no effect on biofilm formation under other genetic and medium conditions. The biofilm defect could be complemented by wild-type RscS and by an RscS chimera that contains the N-terminal domains of RscS fused to the C-terminal HPT domain of SypF, the downstream sensor kinase. It could not be complemented by derivatives that lacked the periplasmic sensory domain or contained a mutation in the conserved site of phosphorylation, H412, suggesting that these cues promote signaling through RscS. Lastly,
pABA and/or calcium was able to induce biofilm formation when rscS was introduced into a heterologous system. Taken together, these data suggest that RscS is responsible for recognizing
pABA and calcium, or downstream consequences of those cues, to induce biofilm formation. This study thus provides insight into signals and regulators that promote biofilm formation by V. fischeri. IMPORTANCE Bacterial biofilms are common in a variety of environments. Infectious biofilms formed in the human body are notoriously hard to treat due to a biofilm\'s intrinsic resistance to antibiotics. Bacteria must integrate signals from the environment to build and sustain a biofilm and often use sensor kinases that sense an external signal, which triggers a signaling cascade to elicit a response. However, identifying the signals that kinases sense remains a challenging area of investigation. Here, we determine that a hybrid sensor kinase, RscS, is crucial for Vibrio fischeri to recognize para-aminobenzoic acid and calcium as cues to induce biofilm formation. This study thus advances our understanding of the signal transduction pathways leading to biofilm formation.