Biofilm-forming bacteria, including the Gram-negative Pseudomonas aeruginosa, cause multiple types of chronic infections and are responsible for serious health burdens in humans, animals, and plants. Nitric oxide (NO) has been shown to induce biofilm dispersal via triggering a reduction in cyclic-di-GMP levels in a variety of bacteria. However, how NO, at homeostatic levels, also facilitates biofilm formation is unknown. Here, we found that complestatin, a structural analog of vancomycin isolated from Streptomyces, inhibits P. aeruginosa biofilm formation by upregulating NO production via nitrite reductase (NIR) induction and c-di-GMP degradation via phosphodiesterase (PDE) stimulation. The complestatin protein target was identified as a nitrite transporter from a genome-wide screen using the Keio Escherichia coli knockout library and confirmed using nitrite transporter knockout and overexpression strains. We demonstrated that the nitrite transporter stimulated biofilm formation by controlled NO production via appropriate NIR suppression and subsequent diguanylate cyclase (DGC) activation, not PDE activity, and c-di-GMP production in E. coli and P. aeruginosa. Thus, this study provides a mechanism for NO-mediated biofilm formation, which was previously not understood.

中文翻译：

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亚硝酸盐转运蛋白通过抑制亚硝酸盐还原酶促进生物膜的形成，并且是铜绿假单胞菌中新的抗生物膜靶标。

生物膜形成细菌，包括革兰氏阴性铜绿假单胞菌，会导致多种类型的慢性感染，并给人类，动物和植物造成严重的健康负担。一氧化氮（NO）已显示出通过触发多种细菌中环二GMP含量的降低而诱导生物膜扩散。然而，在稳态水平的NO如何促进生物膜的形成还未知。在这里，我们发现complestatin是从链霉菌中分离出的万古霉素的结构类似物，可抑制铜绿假单胞菌通过上调亚硝酸还原酶（NIR）诱导的NO产生和通过磷酸二酯酶（PDE）刺激的c-di-GMP降解来形成生物膜。使用Keio Escherichia coli基因敲除文库从全基因组筛选中将complestatin蛋白靶标鉴定为亚硝酸盐转运蛋白，并使用亚硝酸盐转运蛋白敲除和过表达菌株确认了其功能。我们证明了亚硝酸盐转运蛋白通过适当的NIR抑制和随后的二鸟苷酸环化酶（DGC）活化而不是PDE活性以及c-di-GMP在大肠杆菌和铜绿假单胞菌中的产生，通过控制NO的产生来刺激生物膜的形成。因此，这项研究为NO介导的生物膜形成提供了一种机制，这以前是未知的。