|Synonyms: SoxR, SoxR-[2Fe-2S]3+ oxydized, SoxR-[2Fe-2S]2+ reduced|
The SoxR protein, for Superoxide Response protein, is negatively autoregulated and controls the transcription of the regulon involved in defense against redox-cycling drugs |CITS: | and in responses to nitric oxide |CITS: |. SoxR belongs to the MerR family and is a homodimer in solution |CITS: |.
SoxR contains two essential [2Fe-2S] clusters for its transcriptional activity |CITS: |. Each SoxR polypeptide contains a [2Fe-2S] cluster that senses the oxidants in the cell. Both Fe-SoxR and apo-SoxR bind to the promoter region, but only Fe-SoxR contributes to the activation in its oxidized form |CITS: |. The redox state of the iron-sulfur cluster regulates SoxR activity |CITS: |. SoxR contains two critical amino acids around the [2Fe-2S] binding site (RL126R/V130P) and also R127L and P131V substitutions in EcSoxR, which cause a more electropositive environment around [2Fe-2S], making oxidation more difficult |CITS: |.
It has long been known that SoxR senses superoxide |CITS: |; however, Gu and Imlay (2011) concluded that SoxR actually senses redox-cycling agents |CITS: |. But Liochev and Fridovich reported that the superoxide is indeed sensed by SoxR |CITS: [ 21459140]|. The metal core structural and redox states of the metal active sites of SoxR in the presence and absence of O2 and/or NO have been determined |CITS: |.
SoxR and SoxS are two transcription factors that govern a set of genes |CITS: | in which the two regulators act sequentially |CITS: |.
SoxR induces soxS expression, and SoxS, in turn, activates transcription of genes of the regulon |CITS: |.Read more >
Under oxidative stress conditions, translation of soxR is increased by the presence of polyamines. The increase is dependent on the suboptimal placement of the Shine-Dalgarno region upstream of the soxR open reading frame |CITS: |.
Reviews: |CITS: |
|Sensing class:||Using internal synthesized signals|
|Connectivity class:||Local Regulator|
|Length:||465 bp / 154 aa|
|TU(s) encoding the TF:||
|Regulated gene(s)||fumC, soxR, soxS|
|Multifun term(s) of regulated gene(s)||
MultiFun Term (List of genes associated to the multifun term)
Transcription related (2)
other (mechanical, nutritional, oxidative stress) (2)
soxR, soxSRead more >
|Regulated operon(s)||fumAC, soxR, soxS|
|First gene in the operon(s)||fumC, soxR, soxS|
|Simple and complex regulons|
|Simple and complex regulatory phrases||
Regulatory phrase (List of promoters regulated by the phrase)
|Functional conformation||Function||Promoter||Sigma factor||Central Rel-Pos||Distance to first Gene||Genes||Sequence||LeftPos||RightPos||Growth Conditions||Evidence (Confirmed, Strong, Weak)||References|
|4277440||4277457||nd||[BPP], [GEA]||, |
|4277440||4277457||[a]||[BPP], [GEA]||, |
[a] Paraquat treatment
|Evolutionary conservation of regulatory elements|
 Hidalgo E., Bollinger JM., Bradley TM., Walsh CT., Demple B., 1995, Binuclear [2Fe-2S] clusters in the Escherichia coli SoxR protein and role of the metal centers in transcription., J Biol Chem. 270(36):20908-14
 Fuentes AM., Diaz-Mejia JJ., Maldonado-Rodriguez R., Amabile-Cuevas CF., 2001, Differential activities of the SoxR protein of Escherichia coli: SoxS is not required for gene activation under iron deprivation., FEMS Microbiol Lett. 201(2):271-5