While the array of emergent properties assigned to biofilms is extensive (e.g. antimicrobial tolerance), the mechanisms that underpin these are largely unknown. In particular, the extracellular matrix, a defining feature of biofilms, remains poorly understood in terms of its composition and contribution to biofilm structure and function. Here we demonstrate that extracellular DNA exists in a complex with RNA that forms the main cross-linking exopolymer of Pseudomonas biofilms, and explains biofilm elasticity. The RNA has a high purine content and our solid-state NMR data indicate the formation of Hoogsteen guanine base pairs. This may suggest the presence of G-quadruplexes, which is also corroborated by the enhancement of biofilm formation in the presence of potassium. The finding that non-canonical interactions mediate networking of matrix-forming extracellular nucleic acids addresses how eDNA is organized and contributes to matrix biophysical properties. This understanding will allow for the development of more effective biofilm control strategies.

中文翻译：

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假单胞菌属物种的生物膜基质支架包含非规范碱基配对的细胞外DNA和RNA

虽然分配给生物膜的一系列新兴特性（例如，抗菌素耐受性）广泛，但支撑这些特性的机制却鲜为人知。特别地，就其组成以及对生物膜结构和功能的贡献而言，细胞膜外基质（生物膜的主要特征）仍然知之甚少。在这里，我们证明细胞外DNA与RNA形成复合物，形成了假单胞菌的主要交联外聚合物生物膜，并解释生物膜的弹性。RNA具有较高的嘌呤含量，我们的固态NMR数据表明了Hoogsteen鸟嘌呤碱基对的形成。这可能表明存在G-四链体，而钾存在下生物膜形成的增强也证实了G-四链体的存在。非规范相互作用介导形成基质的细胞外核酸网络的发现解决了eDNA的组织方式并有助于基质的生物物理特性。这种理解将有助于开发更有效的生物膜控制策略。