Regulation of sod genes in Escherichia coli: relevance to superoxide dismutase function.
This review is concerned with the effects of environmental perturbations on the expression of the two superoxide dismutase (SOD) genes in Escherichia coli (sodA, MnSOD; sodB, FeSOD). Early studies using SOD activity, showed that MnSOD levels respond to changes in oxygen tension, type of substrate, redox active compounds, iron concentration, the nature of the terminal oxidant, and the redox potential of the medium. FeSOD levels appeared nominally insensitive to these perturbations. More recent molecular genetic studies revealed that sodA expression is subject to regulation by three major regulatory systems: fur (ferric uptake regulation) and arcA arcB (aerobic respiratory control) mediate repression of sodA, while a relatively new system, soxR soxS (superoxide response), mediates activation of sodA expression. By contrast, sodB expression, which is much less studied at this time, appears to be positively activated in trans by fur. A rudimentary gene regulation model is presented which rationalizes past observations, is experimentally testable, and should serve as a guide to future research in this area.
Fee
J A
JA
Biochemistry Section, Los Alamos National Laboratory, Los Alamos, New Mexico 87545.
D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D004790:Enzyme Induction; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics*; D015534:Trans-Activators; D014157:Transcription Factors / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C041610:arcA protein, E coli; C068477:ferric uptake regulating proteins, bacterial; C070724:SoxR protein, Bacteria; C070725:SoxS protein, E coli; D007501:Iron; D013482:Superoxide Dismutase; D010100:Oxygen