Differential activities of the SoxR protein of Escherichia coli: SoxS is not required for gene activation under iron deprivation.
When Escherichia coli cells are under superoxide stress, proteins SoxR and SoxS, acting sequentially, control the expression of a set of repair and defense genes. One of these genes, fumC, encoding fumarase C, was reported to be also activated by iron deprivation in a soxRS-dependent manner. However, the same condition failed to induce the expression of a soxS'::lacZ fusion. The expression of acnA (aconitase A) is also activated by SoxR alone when under iron deprivation, but not of sodA (Mn-superoxide-dismutase). SoxR completely inhibited the migration of a DNA fragment containing the promoter region of fumC, in gel-shift experiments. SoxR might bind to a different region than SoxS within the fumC promoter, or an unknown intermediate other than SoxS might be acting. It is possible that the regulatory role of SoxR is more complex than previously considered.
Fuentes
A M
AM
Fundación LUSARA, México, D.F., México.
Díaz-Mejía
J J
JJ
Maldonado-Rodríguez
R
R
Amábile-Cuevas
C F
CF
D000154:Aconitate Hydratase / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005798:Genes, Bacterial / Q000235:genetics; D005809:Genes, Regulator / Q000235:genetics; D007501:Iron / Q000494:pharmacology*; D000090463:Iron Deficiencies; D009154:Mutation / Q000235:genetics; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic / Q000235:genetics; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D001616:beta-Galactosidase / Q000096:biosynthesis
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D013481:Superoxides; C070724:SoxR protein, Bacteria; C070725:SoxS protein, E coli; D007501:Iron; D013482:Superoxide Dismutase; D001616:beta-Galactosidase; D000154:Aconitate Hydratase