title: Dioxygen and temperature dependence of ubiquinone formation in Escherichia coli: studies of cells charged with 2-octaprenyl phenol.
abstract: The multiple aromatic auxotroph Escherichia coli K-12 strain AB 2847 (aroB-) was conditioned for efficient ubiquinone-8 formation. Resting cells readily convert 4-hydroxy[U-14C]benzoate into ubiquinone-8 (60 nmol per g wet weight). Under argon this processing stops at the stage of 2-octaprenyl phenol. Only upon admission of air is the pool of 2-octaprenyl phenol converted to ubiquinone-8. This reaction occurs in the cytoplasmic membrane and is significantly inhibited by cytochrome P-450 inhibitors. The rate for 2-octaprenyl phenol conversion is strongly dependent on temperature. The Arrhenius plot shows inflection points at 32 degrees C and 16 degrees C. Enzymes for ubiquinone-8 synthesis are absent from anaerobically grown E. coli. Processing of 4-hydroxy[U-14C]benzoate by these cells starts only when protein synthesis is permitted under aerobic conditions.
mesh_terms: D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D062385:Hydroxybenzoates / Q000378:metabolism; D007700:Kinetics; D009154:Mutation; D010100:Oxygen / Q000494:pharmacology*; D013045:Species Specificity; D013696:Temperature; D013729:Terpenes; D014451:Ubiquinone / Q000096:biosynthesis*
chemical_list: D062385:Hydroxybenzoates; D013729:Terpenes; D014451:Ubiquinone; C018118:2-octaprenyl phenol; D003577:Cytochrome P-450 Enzyme System; D010100:Oxygen