title: A mechanism for complementation of the sodA sodB defect in Escherichia coli by overproduction of the rbo gene product (desulfoferrodoxin) from Desulfoarculus baarsii.
abstract: Overexpression of rbo in Escherichia coli prevents the inactivation of the [4Fe-4S]-containing fumarases that otherwise occurs in the sodA sodB strain. It similarly protects against the increased sensitivity toward H2O2, which is imposed by the lack of SOD A and SOD B. These results would be explained on the basis of scavenging of O-2 within the cells by RBO. This interpretation was supported by measurements of intracellular scavenging of O-2 by the lucigenin luminescence method. Since SOD activity could not be detected in dilute extracts, of the RBO-overexpressing sodA sodB strain, we propose that RBO catalyzes the reduction of O-2 at the expense of cellular reductants such as NAD(P)H. A similar mechanism may apply to other instances of complementation of SOD defects by non-SOD genes.
authors.affiliation: Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: S I
authors.initials: SI
authors.lastname: Liochev
authors.forename: I
authors.initials: I
authors.lastname: Fridovich
mesh_terms: D000166:Acridines / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003901:Desulfovibrio / Q000201:enzymology* / Q000235:genetics; D004926:Escherichia coli; D005288:Ferredoxins / Q000235:genetics / Q000378:metabolism*; D016166:Free Radical Scavengers / Q000378:metabolism; D005649:Fumarate Hydratase / Q000378:metabolism; D005816:Genetic Complementation Test; D006861:Hydrogen Peroxide / Q000378:metabolism; D008163:Luminescent Measurements; D010100:Oxygen / Q000378:metabolism; D010641:Phenotype; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*
chemical_list: D000166:Acridines; D001426:Bacterial Proteins; D005288:Ferredoxins; D016166:Free Radical Scavengers; C066602:desulfoferrodoxin; C033472:10,10'-dimethyl-9,9'-biacridinium; D006861:Hydrogen Peroxide; C095500:SodA protein, Bacteria; C087504:SodB protein, Bacteria; D013482:Superoxide Dismutase; D005649:Fumarate Hydratase; D010100:Oxygen