Difference between amino acid residues in the metal-ligand environments of iron- and manganese-superoxide dismutases.
Alignment of the amino acid sequences of the Pseudomonas ovalis and Photobacterium leiognathi iron-superoxide dismutases (Fe-SODs) with the known sequences of the manganese-superoxide dismutases (Mn-SODs) shows that both types of SOD are highly homologous (33-53% identity) and share residues for the metal coordination. The amino acid residues that form the environment of the metal ions appear to be also conserved between the Fe- and Mn-SODs, except that the Phe-84 and Gln-154 in the Mn-SODs are replaced by Tyr and Ala, respectively, in the Fe-enzymes. Since this latter residue contributes to formation of the hydrophobic metal-ligand environment through hydrogen bonding with Trp-133 and Tyr-34 in the Mn-SODs, its substitution by Ala should cause different micro environments between the metal centers of the Fe- and Mn-SODs. This difference may account for the metal specificity of both types of SODs demonstrated by previous reconstitution experiments.
Isobe
T
T
Department of Chemistry, Faculty of Science, Tokyo Metropolitan University.
Fang
Y I
YI
Muno
D
D
Okuyama
T
T
Ohmori
D
D
Yamakura
F
F
D000595:Amino Acid Sequence; D007501:Iron; D008024:Ligands; D008345:Manganese; D008969:Molecular Sequence Data; D010776:Photobacterium / Q000201:enzymology* / Q000235:genetics; D011549:Pseudomonas / Q000201:enzymology* / Q000235:genetics; D013045:Species Specificity; D013482:Superoxide Dismutase / Q000235:genetics*
D008024:Ligands; D008345:Manganese; D007501:Iron; D013482:Superoxide Dismutase