Abstract
The crystal structure of SEp22, a DNA-binding protein from starved cells from Salmonella enterica subsp. enterica serovar Enteritidis, has been determined in two forms: the native state at 1.25 Å resolution and an iron-soaked form at 1.30 Å resolution. The SEp22 protomers form a dodecameric shell with 23 symmetry and a single iron ion per protomer was found at the ferroxidase centre in the iron-soaked form. Along the threefold axes of the 23 symmetry, hydrophilic Asp channels that consist of Asp146 were found. Iron ions may flow into the cavity of the dodecameric shell through the Asp channels.