title: The Bacillus subtilis EfeUOB transporter is essential for high-affinity acquisition of ferrous and ferric iron.
abstract: Efficient uptake of iron is of critical importance for growth and viability of microbial cells. Nevertheless, several mechanisms for iron uptake are not yet clearly defined. Here we report that the widely conserved transporter EfeUOB employs an unprecedented dual-mode mechanism for acquisition of ferrous (Fe[II]) and ferric (Fe[III]) iron in the bacterium Bacillus subtilis. We show that the binding protein EfeO and the permease EfeU form a minimal complex for ferric iron uptake. The third component EfeB is a hemoprotein that oxidizes ferrous iron to ferric iron for uptake by EfeUO. Accordingly, EfeB promotes growth under microaerobic conditions where ferrous iron is more abundant. Notably, EfeB also fulfills a vital role in cell envelope stress protection by eliminating reactive oxygen species that accumulate in the presence of ferrous iron. In conclusion, the EfeUOB system contributes to the high-affinity uptake of iron that is available in two different oxidation states.
authors.affiliation: Department of Chemistry/Biochemistry, Philipps University Marburg, Marburg, Germany. miethke@chem.ucla.edu
authors.forename: Marcus
authors.initials: M
authors.lastname: Miethke
authors.forename: Carmine G
authors.initials: CG
authors.lastname: Monteferrante
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Marahiel
authors.forename: Jan Maarten
authors.initials: JM
authors.lastname: van Dijl
mesh_terms: D001412:Bacillus subtilis / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D003432:Cross-Linking Reagents; D004578:Electron Spin Resonance Spectroscopy; D005290:Ferric Compounds / Q000378:metabolism*; D005296:Ferrous Compounds / Q000378:metabolism*; D005453:Fluorescence; D006420:Hemeproteins / Q000378:metabolism; D015151:Immunoblotting; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003432:Cross-Linking Reagents; D005290:Ferric Compounds; D005296:Ferrous Compounds; D006420:Hemeproteins; D026901:Membrane Transport Proteins; D009195:Peroxidase
keywords: Iron uptake; Oxidative stress; Tat; YwbL; YwbM; YwbN