Open AccessSpecies-specific recruitment of transcription factors dictates toxin expression
Author(s) -
Julian Trouillon,
Erwin Sentausa,
Michel Ragno,
Mylène Robert-Genthon,
Stephen Lory,
Ina Attrée,
Sylvie Elsen
Publication year - 2020
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/gkz1232
Subject(s) - biology , regulon , operon , virulence , repressor , genetics , pseudomonas aeruginosa , promoter , gene , conserved sequence , regulation of gene expression , genome , regulatory sequence , transcription factor , gene expression , escherichia coli , bacteria , peptide sequence
Tight and coordinate regulation of virulence determinants is essential for bacterial biology and involves dynamic shaping of transcriptional regulatory networks during evolution. The horizontally transferred two-partner secretion system ExlB–ExlA is instrumental in the virulence of different Pseudomonas species, ranging from soil- and plant-dwelling biocontrol agents to the major human pathogen Pseudomonas aeruginosa. Here, we identify a Cro/CI-like repressor, named ErfA, which together with Vfr, a CRP-like activator, controls exlBA expression in P. aeruginosa. The characterization of ErfA regulon across P. aeruginosa subfamilies revealed a second conserved target, the ergAB operon, with functions unrelated to virulence. To gain insights into this functional dichotomy, we defined the pan-regulon of ErfA in several Pseudomonas species and found ergAB as the sole conserved target of ErfA. The analysis of 446 exlBA promoter sequences from all exlBA+ genomes revealed a wide variety of regulatory sequences, as ErfA- and Vfr-binding sites were found to have evolved specifically in P. aeruginosa and nearly each species carries different regulatory sequences for this operon. We propose that the emergence of different regulatory cis-elements in the promoters of horizontally transferred genes is an example of plasticity of regulatory networks evolving to provide an adapted response in each individual niche.