Intracellular expression of Vitreoscilla hemoglobin alters Escherichia coli energy metabolism under oxygen-limited conditions.
An earlier stoichiometric analysis of oxygen-limited metabolism of Escherichia coli expressing cloned Vitreoscilla hemoglobin (VHb) suggested improved efficiency of ATP production relative to wild-type controls [Khosla, C., Curtis, J. E., DeModena, J., Rinas, J. & Bailey, J. E. (1990) BioTechnol. 8, 849-853]. This hypothesis has been further examined by determining several energetic parameters of different VHb-expressing E. coli (VHb+) strains relative to controls not expressing VHb (VHb-). The H+/O ratio, the transmembrane delta pH, and the ATP content of VHb+ constructs are 1.5, 1.6 and 2 times, respectively, corresponding values in VHb- controls. VHb was expressed using a low-copy-number vector in E. coli mutant strains lacking cytochrome o, cytochrome d, or both terminal oxidases; significant growth enhancement due to VHb expression was observed only in the strain having functional cytochrome o and lacking cytochrome d. All of these data obtained using different E. coli strains are consistent with a model of VHb action that hypothesizes enhancement by VHb of activity of the lower oxygen-affinity, higher proton-pumping-efficiency cytochrome o terminal oxidase under oxygen-limited growth conditions.
Kallio
P T
PT
Institut für Biotechnologie, ETH-Hönggerberg, Zürich, Switzerland.
Kim
D J
DJ
Tsai
P S
PS
Bailey
J E
JE
D000332:Aerobiosis; D041963:Bacteroidetes / Q000378:metabolism*; D003001:Cloning, Molecular; D003573:Cytochrome b Group; D017937:Cytochrome d Group / Q000378:metabolism; D003580:Cytochromes / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015870:Gene Expression; D005838:Genotype; D006454:Hemoglobins / Q000096:biosynthesis*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010100:Oxygen / Q000494:pharmacology*; D010101:Oxygen Consumption; D010710:Phosphates / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis*; D012265:Ribonucleotides / Q000378:metabolism
D003573:Cytochrome b Group; D003580:Cytochromes; D029968:Escherichia coli Proteins; D006454:Hemoglobins; D010710:Phosphates; D011994:Recombinant Proteins; D012265:Ribonucleotides; D017937:Cytochrome d Group; C017168:cytochrome bo, E coli; D010100:Oxygen