Comparisons of oxidative stress response genes in aerobic Escherichia coli fermentations.
The promoter regions of five SoxRS regulon genes (sodA, fumC, zwf, acnA, and acrAB) and one SoxRS regulatory protein gene (soxS) were inserted upstream of the gene of green fluorescent protein (GFP) in pGlow-TOPO. These promoter probe plasmids were transformed into Escherichia coli Top10 resulting in six strains that produce GFP in response to superoxide-induced stresses. Initial characterization from paraquat insults revealed significant induction of all six genes, with sodA, fumC, zwf, and soxS leading to the others in time and strength. These stress probe strains were then grown under similar conditions in fermentors and systematically exposed to varying durations of pure oxygen. Significant stimulation of the regulon was observed and quantitatively and temporally characterized by online monitoring of GFP fluorescence production (with transcriptional rate sodA > fumC > soxS, zwf > acnA, acrAB = 0). Interestingly, SoxRS regulon response occurred in typical E. coli fermentations where DO is maintained approximately 30% with increased agitation speed (with transcriptional rate acnA > sodA > zwf > acrAB > soxS, fumC = 0). These results also suggest that different molecular responses occur under different aeration schemes, all of which are intended to combat oxidative damage.
Lu
Canghai
C
Department of Chemical and Biochemical Engineering, University of Maryland Baltimore County, Baltimore, MD 21250, USA.
Bentley
William E
WE
Rao
Govind
G
D000332:Aerobiosis; D003198:Computer Simulation; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D016254:Mutagenesis, Insertional; D018384:Oxidative Stress / Q000235:genetics*; D010100:Oxygen / Q000378:metabolism; D010269:Paraquat / Q000378:metabolism; D010957:Plasmids; D011401:Promoter Regions, Genetic; D018085:Regulon; D013481:Superoxides / Q000378:metabolism; D014158:Transcription, Genetic
D029968:Escherichia coli Proteins; D008164:Luminescent Proteins; D013481:Superoxides; D049452:Green Fluorescent Proteins; D010269:Paraquat; D010100:Oxygen