title: Structure-function analysis of recombinant substrate protein 22 kDa (SP-22). A mitochondrial 2-CYS peroxiredoxin organized as a decameric toroid.
abstract: Bovine mitochondrial SP-22 is a member of the peroxiredoxin family of peroxidases. It belongs to the peroxiredoxin 2-Cys subgroup containing three cysteines at positions 47, 66, and 168. The cloning and overexpression in Escherichia coli of recombinant wild type SP-22 and its three cysteine mutants (C47S, C66S, and C168S) are reported. Purified His-tagged SP-22 was fully active with Cys-47 being confirmed as the catalytic residue. The enzyme forms a stable decameric toroid consisting of five basic dimeric units containing intermolecular disulfide bonds linking the catalytically active Cys-47 of one subunit and Cys-168 of the adjacent monomer. The disulfide bonds are not required for overall structural integrity. The toroidal units have average external and internal diameters of 15 and 7 nm, respectively, and can form stacks in a lateral arrangement of two or three rings. C47S had a pronounced tendency to stack in long tubular structures containing up to 60 rings. Further unusual structural features are the presence of radial spikes projecting from the external surface and ordered electron-dense material within the central cavity of the toroid.
authors.affiliation: Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom.
authors.forename: Louise J
authors.initials: LJ
authors.lastname: Gourlay
authors.forename: David
authors.initials: D
authors.lastname: Bhella
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Kelly
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Price
authors.forename: J Gordon
authors.initials: JG
authors.lastname: Lindsay
mesh_terms: D000818:Animals; D002384:Catalysis; D002417:Cattle; D002942:Circular Dichroism; D003001:Cloning, Molecular; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003545:Cysteine / Q000737:chemistry; D003553:Cystine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D006639:Histidine / Q000737:chemistry; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010544:Peroxidases / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D054464:Peroxiredoxins; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship
chemical_list: D003432:Cross-Linking Reagents; D004220:Disulfides; D003553:Cystine; D006639:Histidine; D010544:Peroxidases; D054464:Peroxiredoxins; D010751:Phosphopyruvate Hydratase; D003545:Cysteine