Koirala Pratik, Doody Cassie, Blackwell Helen, Chandler Josephine R
Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045 USA.
Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706 USA.
bioRxiv. 2023 Sep 3:2023.09.02.556004. doi: 10.1101/2023.09.02.556004.
The soil bacterium uses a single LuxI-R-type quorum-sensing system, CviI-R, to regulate genes in a cell density-dependent manner. CviI synthesizes the signal -hexanoyl-homoserine lactone (C6-HSL) and CviR is a C6-HSL-responsive cytoplasmic transcription regulator. C6-HSL-bound CviR activates dozens of genes, for example the cluster coding for an efflux pump conferring antibiotic resistance. The genes are also regulated by an antibiotic-responsive transcription factor, CdeR, which represses expression of these genes. We are interested in understanding how integrates different environmental cues to regulate antibiotic resistance. In this study, we sought to delineate the mechanism of regulation of the genes by CviR and CdeR. In recombinant the promoter is activated by CviR and repressed by CdeR. We identify non-overlapping sequence elements in the promoter that are required for CviR activation and CdeR repression, respectively. We also examined the role of CdeR in modulating activation by C6-HSL in . We show that CviR and CdeR can independently modulate transcription from the promoter in , consistent with the conclusion that CviR and CdeR regulate the genes by interacting directly with different binding sites in the promoter. These results contribute to a molecular understanding of how the genes are regulated and provide new insight into how integrates different environmental cues to regulate antibiotic resistance.
这种土壤细菌利用单一的LuxI-R型群体感应系统CviI-R，以细胞密度依赖的方式调控基因。CviI合成信号分子己酰基高丝氨酸内酯（C6-HSL），CviR是一种对C6-HSL有反应的细胞质转录调节因子。与C6-HSL结合的CviR激活数十个基因，例如编码赋予抗生素抗性的外排泵的基因簇。这些基因也受到一种抗生素反应性转录因子CdeR的调控，CdeR会抑制这些基因的表达。我们感兴趣的是了解该细菌如何整合不同的环境信号来调控抗生素抗性。在本研究中，我们试图阐明CviR和CdeR对这些基因的调控机制。在重组细菌中，这些基因的启动子被CviR激活并被CdeR抑制。我们确定了这些基因启动子中分别对于CviR激活和CdeR抑制所必需的非重叠序列元件。我们还研究了CdeR在调节细菌中C6-HSL介导的激活作用中的角色。我们表明，CviR和CdeR可以独立地调节细菌中这些基因启动子的转录，这与CviR和CdeR通过直接与这些基因启动子中的不同结合位点相互作用来调控这些基因的结论一致。这些结果有助于从分子层面理解这些基因是如何被调控的，并为该细菌如何整合不同的环境信号来调控抗生素抗性提供了新的见解。
