State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, Shandong, China.
Nat Commun. 2018 Jul 2;9(1):2563. doi: 10.1038/s41467-018-05004-y.
The virulence factor pyocyanin and the intracellular second messenger cyclic diguanylate monophosphate (c-di-GMP) play key roles in regulating biofilm formation and multi-drug efflux pump expression in Pseudomonas aeruginosa. However, the crosstalk between these two signaling pathways remains unclear. Here we show that BrlR (PA4878), previously identified as a c-di-GMP responsive transcriptional regulator, acts also as a receptor for pyocyanin. Crystal structures of free BrlR and c-di-GMP-bound BrlR reveal that the DNA-binding domain of BrlR contains two separate c-di-GMP binding sites, both of which are involved in promoting brlR expression. In addition, we identify a pyocyanin-binding site on the C-terminal multidrug-binding domain based on the structure of the BrlR-C domain in complex with a pyocyanin analog. Biochemical analysis indicates that pyocyanin enhances BrlR-DNA binding and brlR expression in a concentration-dependent manner.
毒力因子绿脓菌素和细胞内第二信使环二鸟苷酸单磷酸（c-di-GMP）在调节铜绿假单胞菌生物膜形成和多药外排泵表达中起关键作用。然而，这两种信号通路之间的串扰尚不清楚。在这里，我们表明，BrlR（PA4878），先前被鉴定为 c-di-GMP 反应性转录调节因子，也作为绿脓菌素的受体发挥作用。游离 BrlR 和 c-di-GMP 结合的 BrlR 的晶体结构表明，BrlR 的 DNA 结合结构域包含两个独立的 c-di-GMP 结合位点，这两个位点都参与促进 brlR 表达。此外，我们基于 BrlR-C 结构域与绿脓菌素类似物复合物的结构，在 C 末端多药物结合结构域上鉴定出一个绿脓菌素结合位点。生化分析表明，绿脓菌素以浓度依赖的方式增强 BrlR-DNA 结合和 brlR 表达。
