title: Respiratory mutants of Azotobacter vinelandii with elevated levels of cytochrome d.
abstract: A method is described for the isolation of respiratory mutants of Azotobacter vinelandii with increased amounts of d-type cytochrome by selecting for the inability to reduce tetrazolium red. Five stable mutants were obtained that had six-fold higher levels of cytochrome d, increased amounts of b-type and lower amounts of o-type and c-type cytochromes than the wild-type strain. Spectral alterations in cytochrome alpha 1 were also observed in the mutants. NADH and succinate oxidase activities of membrane particles were about two fold higher in the mutants compared to the wild-type strain. Ascorbate-N,N,N',N'-tetramethyl-p-phenylene diamine oxidase activity was barely detectable in membrane particles of the mutants. These results are consistent with an increase in the amount of the cytochrome d oxidase branch and a decrease in the amount and activity of the cytochrome o, alpha 1 oxidase branch in the mutants. Growth rates under oxygen-excess conditions and respiratory-linked proton translocation ratios of the mutant and wild-type stains were similar as were the photochemical spectral and kinetic properties of cytochrome d.
mesh_terms: D001395:Azotobacter / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D003470:Culture Media; D017937:Cytochrome d Group; D003580:Cytochromes / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D004579:Electron Transport; D006859:Hydrogen / Q000032:analysis; D007700:Kinetics; D009154:Mutation; D010100:Oxygen / Q000032:analysis; D010777:Photochemistry; D013057:Spectrum Analysis
chemical_list: D003470:Culture Media; D003580:Cytochromes; D006859:Hydrogen; D017937:Cytochrome d Group; D010100:Oxygen