BrlR from Pseudomonas aeruginosa is a receptor for both cyclic di-GMP and pyocyanin.
Wang, F., He, Q., Yin, J., Xu, S., Hu, W., Gu, L.(2018) Nat Commun 9: 2563-2563
- PubMed: 29967320 
- DOI: https://doi.org/10.1038/s41467-018-05004-y
- Primary Citation of Related Structures:  
5XBI, 5XBT, 5XBW - PubMed Abstract: 
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.
Organizational Affiliation: 
State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, Shandong, China.