The Burkholderia cenocepacia iron starvation σ factor, OrbS, possesses an on-board iron sensor
الباحث الأول:
Aaron T Butt
الباحثين الآخرين:
Christopher D Banyard, Sayali S Haldipurkar, Kirsty Agnoli, Muslim I Mohsin, Srdjan Vitovski, Ameya Paleja, Yingzhi Tang, Rebecca Lomax,
Fuzhou Ye, Jeffrey Green, Mark S Thomas
المجلة:
Nucleic Acids Research
تاريخ النشر:
22 نوفمبر، 2022
مختصر البحث:
Burkholderia cenocepacia is an opportunistic pathogen that causes severe infections of the cystic fibrosis (CF) lung. To acquire iron, B. cenocepacia secretes the Fe(III)-binding compound, ornibactin. Genes for synthesis and utilisation of ornibacti…
Burkholderia cenocepacia is an opportunistic pathogen that causes severe infections of the cystic fibrosis (CF) lung. To acquire iron, B. cenocepacia secretes the Fe(III)-binding compound, ornibactin. Genes for synthesis and utilisation of ornibactin are served by the iron starvation (IS) extracytoplasmic function (ECF) σ factor, OrbS. Transcription of orbS is regulated in response to the prevailing iron concentration by the ferric uptake regulator (Fur), such that orbS expression is repressed under iron-sufficient conditions. Here we show that, in addition to Fur-mediated regulation of orbS, the OrbS protein itself responds to intracellular iron availability. Substitution of cysteine residues in the C-terminal region of OrbS diminished the ability to respond to Fe(II) in vivo. Accordingly, whilst Fe(II) impaired transcription from and recognition of OrbS-dependent promoters in vitro by inhibiting the binding of OrbS to core RNA polymerase (RNAP), the cysteine-substituted OrbS variant was less responsive to Fe(II).
