title: Crystal structure of nickel-containing superoxide dismutase reveals another type of active site.
abstract: 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.
authors.affiliation: International School for Advanced Studies, Via Beirut 2-4, I-34014 Trieste, Italy.
authors.forename: Jochen
authors.initials: J
authors.lastname: Wuerges
authors.forename: Jin-Won
authors.initials: JW
authors.lastname: Lee
authors.forename: Yang-In
authors.initials: YI
authors.lastname: Yim
authors.forename: Hyung-Soon
authors.initials: HS
authors.lastname: Yim
authors.forename: Sa-Ouk
authors.initials: SO
authors.lastname: Kang
authors.forename: Kristina
authors.initials: K
authors.lastname: Djinovic Carugo
mesh_terms: 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
chemical_list: D011994:Recombinant Proteins; D009532:Nickel; D013482:Superoxide Dismutase