The effects of fur on the transcriptional and post-transcriptional regulation of MnSOD gene (sodA) in Escherichia coli.
Earlier studies have shown that the Fur (ferric uptake regulation) protein acts as an anaerobic/aerobic repressor of MnSOD (sodA) expression. We found that the aerobic expression of sodA::lacZ fusion in a Fur- background to be threefold higher than in a Fur+ background. This effect of fur mutation was not seen in a strain harboring the sodA+ gene instead of the sodA::lacZ fusion. However, we observed a proportionate increase in the concentrations of sodA::lacZ and sodA+ mRNAs in response to a mutation in the fur gene. These data suggest that the formation of active MnSOD is dependent on a functional fur gene. Indeed, we found that in a fur mutant iron was incorporated into SodA in place of manganese, thus creating inactive and/or partially active forms of the enzyme (i.e., Fe2SodA and/or Mn,FeSodA, respectively), resulting in little or no increase in total MnSOD activity. Thus, Fur plays the role of a repressor at the transcriptional level, but it also plays an indirect role at the post-transcriptional level where it affects the maturation of SodA into a fully active enzyme, Mn2SodA (MnSOD).
Schrum
L W
LW
Department of Biochemistry, North Carolina State University, Raleigh 27695-7622.
Hassan
H M
HM
D000332:Aerobiosis; D001426:Bacterial Proteins / Q000494:pharmacology*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D007501:Iron / Q000378:metabolism*; D008345:Manganese; D009154:Mutation; D010957:Plasmids; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*; D001616:beta-Galactosidase / Q000235:genetics
D001426:Bacterial Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D008345:Manganese; D007501:Iron; D013482:Superoxide Dismutase; D001616:beta-Galactosidase