Interactions between an anti-sigma protein and two sigma factors that regulate the pyoverdine signaling pathway in Pseudomonas aeruginosa

摘要: Synthesis and uptake of pyoverdine, the primary siderophore opportunistic pathogen Pseudomonas aeruginosa, is dependent on two extra-cytoplasmic function (ECF) sigma factors, FpvI PvdS. PvdS are required for expression ferri-pyoverdine receptor gene fpvA pyoverdine synthesis genes respectively. In absence anti-sigma factor FpvR that spans cytoplasmic membrane inhibits activities both PvdS, despite factors having low sequence identity. To investigate interactions with we first used a tandem affinity purification system to demonstrate binding by region in P. aeruginosa at physiological levels. The bound inhibited when proteins were co-expressed Escherichia coli. Each was then subjected error prone PCR site-directed mutagenesis identify mutations increased activity presence FpvR. FpvI, amino acid changes clustered around conserved four protein likely disrupt Deletion five acids from C-terminal end also disrupted Mutations present regions four. Most these as well deletion thirteen independent whether present, suggesting they increase either stability or its core RNA polymerase. These data show binds E. coli, inhibiting activity. involve protein.