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Structural model of FeoB, the iron transporter from Pseudomonas aeruginosa, predicts a cysteine lined, GTP-gated pore.

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Seyedmohammad, Saeed 
Fuentealba, Natalia Alveal 
Marriott, Robert AJ 
Goetze, Tom A 
Edwardson, J Michael 


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.



FeoB, GTPase (guanosine 5′-triphosphatase), channel, homology modelling, iron acquisition, membrane protein, pathogen, Bacterial Proteins, Cation Transport Proteins, Models, Molecular, Protein Domains, Protein Structure, Quaternary, Pseudomonas aeruginosa

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Bioscience Reports

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Portland Press, Biochemical Society
Wellcome Trust (089125/Z/09/Z)
BBSRC (BB/F017464/1)
This work was supported by the Wellcome Trust [grant number 089125/Z/09/Z (to T.A.G. and J.M.E.)]; the grants [Fondecyt 1120169, DPI-Conicyt 20140080, Anillo ACT-1108 and ICM-P10-035F (to N.P.B. and N.A.F.)]; the University of South Australia and the Sansom Institute for Health Research (to H.V.); and the BBSRC scholarship [grant number F017464/1 (to S.S.)].