Crystal structure of nickel-containing superoxide dismutase reveals another type of active site.
Superoxide dismutases (SODs, EC 1.15.1.1) are ubiquitous enzymes that efficiently catalyze the dismutation of superoxide radical anions to protect biological molecules from oxidative damage. The crystal structure of nickel-containing SOD (NiSOD) from Streptomyces seoulensis was determined for the resting, x-ray-reduced, and thiosulfate-reduced enzyme state. NiSOD is a homohexamer consisting of four-helix-bundle subunits. The catalytic center resides in the N-terminal active-site loop, where a Ni(III) ion is coordinated by the amino group of His-1, the amide group of Cys-2, two thiolate groups of Cys-2 and Cys-6, and the imidazolate of His-1 as axial ligand that is lost in the chemically reduced state as well as after x-ray-induced reduction. This structure represents a third class of SODs concerning the catalytic metal species, subunit structure, and oligomeric organization. It adds a member to the small number of Ni-metalloenzymes and contributes with its Ni(III) active site to the general understanding of Ni-related biochemistry. NiSOD is shown to occur also in bacteria other than Streptomyces and is predicted to be present in some cyanobacteria.
Wuerges
Jochen
J
International School for Advanced Studies, Via Beirut 2-4, I-34014 Trieste, Italy.
Lee
Jin-Won
JW
Yim
Yang-In
YI
Yim
Hyung-Soon
HS
Kang
Sa-Ouk
SO
Djinovic Carugo
Kristina
K
D000595:Amino Acid Sequence; D020134:Catalytic Domain / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009532:Nickel / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D013302:Streptomyces / Q000201:enzymology / Q000235:genetics; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D011994:Recombinant Proteins; D009532:Nickel; D013482:Superoxide Dismutase