Metal binding to Saccharomyces cerevisiae ferrochelatase.
Ferrochelatase is the terminal enzyme in the heme biosynthetic pathway. It catalyzes the insertion of ferrous iron into protoporphyrin IX to produce protoheme IX. The crystal structures of ferrochelatase from Saccharomyces cerevisiae in free form, in complex with Co(II), a substrate metal ion, and in complex with two inhibitors, Cd(II) and Hg(I), are presented in this work. The enzyme is a homodimer, with clear asymmetry between the monomers with regard to the porphyrin binding cleft and the mode of metal binding. The Co(II) and Cd(II) complexes reveal the metal binding site which consists of the invariant amino acids H235, E314, and S275 and solvent molecules. The shortest distance to the metal reveals that amino acid H235 is the primary metal binding residue. A second site with bound Cd(II) was found close to the surface of the molecule, approximately 14 A from H235, with E97, H317, and E326 participating in metal coordination. It is suggested that this site corresponds to the magnesium binding site in Bacillus subtilis ferrochelatase. The latter site is also located at the surface of the molecule and thought to be involved in initial metal binding and regulation.
Karlberg
Tobias
T
Department of Molecular Biophysics, Centre for Chemistry and Chemical Engineering, Lund University, Sweden.
Lecerof
David
D
Gora
Monika
M
Silvegren
Germund
G
Labbe-Bois
Rosine
R
Hansson
Mats
M
Al-Karadaghi
Salam
S
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology; D001665:Binding Sites; D002104:Cadmium / Q000378:metabolism; D003035:Cobalt / Q000378:metabolism*; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D005294:Ferrochelatase / Q000235:genetics / Q000378:metabolism*; D007501:Iron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011166:Porphyrins / Q000378:metabolism; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid
D011166:Porphyrins; D002104:Cadmium; D003035:Cobalt; D007501:Iron; D005294:Ferrochelatase