Journal:JBIC:4

<scene name='Journal:JBIC:4/Opening/1'>Ferrochelatase</scene> produces <scene name='Journal:JBIC:4/Heme_bound_ferro/4'>heme by insertion of iron into protoporphyrin IX</scene>. It can also <scene name='Journal:JBIC:4/Copper_protorphyrin/4'>insert other metal ions</scene>. However, the ability to insert other metal ions is species specific. In this way Bacillus subtilis ferrochelatase can insert copper,<scene name='Journal:JBIC:4/Co_chelo_bound/2'>but to a much less extent cobalt</scene>. In contrast, the human and Saccharomyces cerevisiae ferrochelatases prefer cobalt over copper. <scene name='Journal:JBIC:4/Iron_binding/7'>Our structural work shows that one His residue and one Glu residue are direct ligands to the metal ion</scene>. A third residue, <scene name='Journal:JBIC:4/Iron_bound_met/2'>Tyr in B. subtilis ferrochelatase and Met in human/S. cerevisiae ferrochelatase,</scene> is a third ligand via a water molecule. In the structures of the ferrochelatases the Tyr/Met occupies the same position. We also know that the Tyr residue of the B. subtilis enzyme is a direct ligand to a copper-porphyrin reaction product. By site directed mutagenesis we changed the Tyr to a Met residue and showed that the metal specificity changed so that the modified B. subtilis ferrochelatase preferred cobalt over copper. Two Proteopedia structures are presented. One shows how <scene name='Journal:JBIC:4/Iron_binding_zoomout/1'>a metal ion (iron) is coordinated in the active site of the B. subtilis ferrochelatase</scene>. The other shows how a <scene name='Journal:JBIC:4/Bound_cu_por/1'>copper in a reaction product (copper-mesoporphyrin) is coordinated by the Tyr residue</scene> in the B. subtilis enzyme.