Norepinephrine derepresses the Fur regulon of Neisseria gonorrhoeae to enable growth in iron-limited conditions

Neisseria gonorrhoeae (Gc) is the Gram-negative bacterium that causes gonorrhea, a prevalent sexually transmitted infection that can have life-threatening clinical sequelae. Gc requires iron for human infection and uses the iron-responsive, iron-binding transcriptional repressor Fur to maintain iron homeostasis. Gc infects mucosal sites, where the neuroendocrine hormone norepinephrine (NE) is produced by the autonomic nervous system and various epithelial and immune cell types. By RNA-seq, we determined that NE rewires gonococcal gene expression to increase capacity for iron uptake while enabling increased intracellular iron availability. Of the 30 genes that were differentially expressed in NE-treated compared to untreated bacteria, 27 have Fur box-containing promoters. Overall design: Neisseria gonorrhoeae of strain background FA1090, constitutively expressing the OpaD protein (PMID: 23625842) was grown to mid-log phase in Chelex-treated chemically defined medium (PMID: 32202529), alone or with 12.5 µM Fe(NO3)3 or with 10 µM norepinephrine for 1 hour. Total RNA was isolated using the RNeasy Plus minikit. Ribosomal RNA was depleted using the NEBNext rRNA depletion kit and the remaining RNA was reverse-transcribed into a cDNA library for Illumina sequencing. Reads were mapped to the FA1090 genome (GCA_009757095.1, ASM975709v1).