2.6 Å resolution crystal structure of the bacterioferritin from Azotobacter vinelandii

The crystal structure of the bacterioferritin from Azotobacter vinelandii has been determined at 2.6 Angstrom resolution. Both the low occupancy of one iron ion in the dinuclear iron center and the deviation of its adjacent residue His130 from the center suggest migration of the iron ion from the dinuclear iron site to the inner nucleation site. The concerted movement of His130 and Glu47 may admit a dynamic gating mechanism for shift of the oxidized iron ion. Ba-2+ binding to the fourfold channel implicates that the channel bears Fe2+ conductivity and selectivity to provide a route for iron access to the inner cavity during core formation. (C) 2004 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.