title: Structural model of FeoB, the iron transporter from Pseudomonas aeruginosa, predicts a cysteine lined, GTP-gated pore.
abstract: Iron is essential for the survival and virulence of pathogenic bacteria. The FeoB transporter allows the bacterial cell to acquire ferrous iron from its environment, making it an excellent drug target in intractable pathogens. The protein consists of an N-terminal GTP-binding domain and a C-terminal membrane domain. Despite the availability of X-ray crystal structures of the N-terminal domain, many aspects of the structure and function of FeoB remain unclear, such as the structure of the membrane domain, the oligomeric state of the protein, the molecular mechanism of iron transport, and how this is coupled to GTP hydrolysis at the N-terminal domain. In the present study, we describe the first homology model of FeoB. Due to the lack of sequence homology between FeoB and other transporters, the structures of four different proteins were used as templates to generate the homology model of full-length FeoB, which predicts a trimeric structure. We confirmed this trimeric structure by both blue-native-PAGE (BN-PAGE) and AFM. According to our model, the membrane domain of the trimeric protein forms a central pore lined by highly conserved cysteine residues. This pore aligns with a central pore in the N-terminal GTPase domain (G-domain) lined by aspartate residues. Biochemical analysis of FeoB from Pseudomonas aeruginosa further reveals a putative iron sensor domain that could connect GTP binding/hydrolysis to the opening of the pore. These results indicate that FeoB might not act as a transporter, but rather as a GTP-gated channel.
authors.affiliation: Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K.
authors.forename: Saeed
authors.initials: S
authors.lastname: Seyedmohammad
authors.affiliation: Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Natalia Alveal
authors.initials: NA
authors.lastname: Fuentealba
authors.affiliation: School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, GPO Box 2471, Adelaide 5001, Australia.
authors.forename: Robert A J
authors.initials: RA
authors.lastname: Marriott
authors.affiliation: Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K.
authors.forename: Tom A
authors.initials: TA
authors.lastname: Goetze
authors.affiliation: Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Edwardson
authors.affiliation: Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile rietie.venter@unisa.edu.au nbarrera@bio.puc.cl.
authors.forename: Nelson P
authors.initials: NP
authors.lastname: Barrera
authors.affiliation: School of Pharmacy and Medical Sciences, Sansom Institute for Health Research, University of South Australia, GPO Box 2471, Adelaide 5001, Australia rietie.venter@unisa.edu.au nbarrera@bio.puc.cl.
authors.forename: Henrietta
authors.initials: H
authors.lastname: Venter
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D027682:Cation Transport Proteins / Q000737:chemistry*; D008958:Models, Molecular; D000072417:Protein Domains; D020836:Protein Structure, Quaternary; D011550:Pseudomonas aeruginosa / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D027682:Cation Transport Proteins
keywords: FeoB; GTPase (guanosine 5′-triphosphatase); channel; homology modelling; iron acquisition; membrane protein; pathogen