Difference between revisions of "Part:BBa K554000"

Revision as of 10:31, 20 October 2020

SoxS promoter

SoxS is a promoter regulated by the SoxR transcription factor, which is activated by NO. E. coli can naturally respond to redox signals through a superoxide stress system composed by SoxR gene, SoxS promoter and the genes associated with SoxS promoter. Thus, in the presence of NO, SoxR activates transcription of the gene regulated by SoxS promoter (Hidalgo et al, 1998). The SoxS promoter is used by [http://2011.igem.org/Team:UNICAMP-EMSE_Brazil UNICAMP-EMSE Brazil team] in the [http://2011.igem.org/Team:UNICAMP-EMSE_Brazil/Project#Device_2:_NO_sensor.2FIL-10_producer NO sensor device/ IL-10 producer] ("Device 2", which senses NO levels and responds by producing and secreting IL-10.

Sequence and Features

Usage and Biology

• This promoter is used by [http://2011.igem.org/Team:UNICAMP-EMSE_Brazil UNICAMP-EMSE Brazil team] in the [http://2011.igem.org/Team:UNICAMP-EMSE_Brazil/Project/Device2 NO sensor device] ("Device 2", which senses NO levels and responds by producing and secreting IL-10. This part is shown in the red box in the following schema:

Three-dimensional structure representation

You can find below a tridimensional structure of Escherichia coli SoxR protein bound to SoxS promoter (DNA structure) (retrieved from PDB 2zhg, Watanabe et al. 2008), with both p35 (chain A) and p40 (chain B) chains. This is a jmol applet, in which you can interactively see the protein format:

MIT MAHE 2020

Usage and Biology

The oxidation state of the iron-sulfur clusters in SoxR regulates the transcriptional activity of the protein: while reduced SoxR does not affect transcription, oxidized SoxR dramatically enhances the transcription rate of soxS, a gene that codes for a second transcriptional activator. The SoxS protein is a member of the AraC/XylS family of transcriptional regulators.

It is a pleiotropic regulator that binds many sites across the genome and plays an important role in antibiotic resistance through its influence on efflux activity. It also impacts biofilm formation, quorum sensing, pathogenicity and motility.

It has been shown that there is a rapid increase in transcription of soxS following exposure to antibiotics (and other inducer substrates), but that repression is rapidly reinstated following removal of the stimuli. The pool of pre-produced transcriptional regulators is degraded by proteases including Lon, and this “resetting” in impaired in lon deficient mutants (Griffith et al., 2004; Ricci et al., 2014). This ability to quickly produce, but then degrade SoxS allows for a fine-tuned, fast response to environmental stimuli to maximize bacterial fitness when under stress.

As well as controlling membrane permeability through efflux pump and outer membrane porin expression, SoxS is important for initiating transcription of genes to reduce superoxide and nitric oxide stress in the cell. When efflux is disrupted, cells respond with overexpression of this transcriptional regulator, though it is not understood by which mechanism this is regulated.

Binding of Fe-SoxR to the wild-type soxS promoter improved the subsequent binding of RNAP nearly 5-fold as determined by densitometric analysis.

As well as AcrAB-TolC, SoxS can also regulate the expression of other efflux pumps, such as the RND pump AcrEF (Bailey et al., 2010) and a member of the multidrug and toxic compound extrusion (MATE) family, mdtK (Sun et al., 2011) in response to environmental stress.

Increased expression of marA, ramA, and soxS up regulates efflux activity to allow detoxification of the cell. However, this also results in trade-offs in other phenotypes, such as impaired growth rates, biofilm formation and virulence.

References

Hidalgo E, Leautaud V, Demple B (1998) The redox-regulated SoxR protein acts from a single DNA site as a repressor and an allosteric activator. The EMBO Journal 17(9)2629–2636 [http://www.ncbi.nlm.nih.gov/pubmed/?term=9564045%20 Link to Pubmed]

Watanabe S, Kita A, Kobayashi K, Miki K. Crystal structure of the [2Fe-2S] oxidative-stress sensor SoxR bound to DNA.Proc Natl Acad Sci U S A. 2008 Mar 18;105(11):4121-6. Epub 2008 Mar 11. [http://www.ncbi.nlm.nih.gov/pubmed/18334645 Link to PubMed]

Holden, E. R., & Webber, M. A. (2020). MarA, RamA, and SoxS as Mediators of the Stress Response: Survival at a Cost. Frontiers in microbiology, 11, 828. https://doi.org/10.3389/fmicb.2020.00828

Pomposiello, P. J., & Demple, B. (2000). Identification of SoxS-regulated genes in Salmonella enterica serovar typhimurium. Journal of bacteriology, 182(1), 23–29. https://doi.org/10.1128/jb.182.1.23-29.2000

Nunoshiba, T., Hidalgo, E., Amábile Cuevas, C. F., & Demple, B. (1992). Two-stage control of an oxidative stress regulon: the Escherichia coli SoxR protein triggers redox-inducible expression of the soxS regulatory gene. Journal of bacteriology, 174(19), 6054–6060. https://doi.org/10.1128/jb.174.19.6054-6060.1992

Structure: