The binding of haem and zinc in the 1.9 A X-ray structure of Escherichia coli bacterioferritin.
Willies SC., Isupov MN., Garman EF., Littlechild JA.
The crystal structure of Escherichia coli bacterioferritin has been solved to 1.9 A, and shows the symmetrical binding of a haem molecule on the local twofold axis between subunits and a pair of metal atoms bound to each subunit at the ferroxidase centre. These metals have been identified as zinc by the analysis of the structure and X-ray data and confirmed by microfocused proton-induced X-ray emission experiments. For the first time the haem has been shown to be linked to both the internal and the external environments via a cluster of waters positioned above the haem molecule.