Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA.
Present address: Stowers Institute for Medical Research, Kansas City, MO 64110, USA.
Microbiology (Reading). 2023 Feb;169(2). doi: 10.1099/mic.0.001294.
Many saprophytic bacteria have LuxR-I-type acyl-homoserine lactone (AHL) quorum-sensing systems that may be important for competing with other bacteria in complex soil communities. LuxR AHL receptors specifically interact with cognate AHLs to cause changes in expression of target genes. Some LuxR-type AHL receptors have relaxed specificity and are responsive to non-cognate AHLs. These promiscuous receptors might be used to sense and respond to AHLs produced by other bacteria by eavesdropping. We are interested in understanding the role of eavesdropping during interspecies competition. The soil saprophyte has a single AHL circuit, CviR-I, which produces and responds to hexanoyl-HSL (C6-HSL). The AHL receptor CviR can respond to a variety of AHLs in addition to C6-HSL. In prior studies we have utilized a coculture model with and another soil saprophyte, . Using this model, we previously showed that promiscuous activation of CviR by AHLs provides a competitive advantage to . Here, we show that AHLs activate transcription of dozens of genes in including the genes coding for production of hydrogen cyanide. We show that hydrogen cyanide production is population density-dependent and demonstrate that the cross-induction of hydrogen cyanide by AHLs provides a competitive advantage to . Our results provide new information on quorum sensing and are the basis for future studies aimed at understanding the role of eavesdropping in interspecies competition.
许多腐生细菌都具有 LuxR-I 型酰基高丝氨酸内酯 (AHL) 群体感应系统，这对于在复杂的土壤群落中与其他细菌竞争可能很重要。LuxR AHL 受体特异性地与同源 AHL 相互作用，导致靶基因表达的变化。一些 LuxR 型 AHL 受体具有宽松的特异性，并且对非同源 AHL 有反应。这些混杂的受体可能被用来通过偷听来感知和响应其他细菌产生的 AHL。我们有兴趣了解在种间竞争中偷听的作用。土壤腐生菌 只有一个 AHL 回路 CviR-I，它产生并响应己酰基-HSL (C6-HSL)。AHL 受体 CviR 除了 C6-HSL 之外，还可以响应各种 AHL。在之前的研究中，我们利用 与另一种土壤腐生菌 的共培养模型。利用该模型，我们之前表明， 通过 AHLs 对 CviR 的混杂激活为 提供了竞争优势。在这里，我们表明 AHLs 激活了 中的数十个基因的转录，包括编码产生氢氰酸的 基因。我们表明氢氰酸的产生是种群密度依赖的，并证明 AHLs 对氢氰酸的交叉诱导为 提供了竞争优势。我们的结果提供了有关 群体感应的新信息，并且是未来旨在了解偷听在种间竞争中的作用的研究的基础。
