Spx

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  • Description: transcriptional regulator Spx, involved in regulation of many genes.

Gene name spx
Synonyms yjbD
Essential no
Product transcriptional regulator Spx
Function negative and positive regulator of many genes
Interactions involving this protein in SubtInteract: Spx
Metabolic function and regulation of this protein in SubtiPathways:
Riboflavin / FAD
MW, pI 15,5 kDa, 7.80
Gene length, protein length 393 bp, 131 amino acids
Immediate neighbours yjbC, yjbE
Get the DNA and protein sequences
(Barbe et al., 2009)
Genetic context
Spx context.gif
This image was kindly provided by SubtiList








Categories containing this gene/protein

transcription factors and their control, general stress proteins (controlled by SigB), cell envelope stress proteins (controlled by SigM, V, W, X, Y)

This gene is a member of the following regulons

PerR regulon, SigB regulon, SigM regulon, SigW regulon, SigX regulon

The Spx regulon

The gene

Basic information

  • Locus tag: BSU11500

Phenotypes of a mutant

Loss of up-regulation of the methionine sulfoxide reductase (msrA-msrB) operon in response to thiol specific oxidative stress, also loss of trxA and trxB upregulation in response to thiol specific oxidative stress.

Database entries

  • DBTBS entry: [1]
  • SubtiList entry: link

Additional information

The protein

Basic information/ Evolution

  • Catalyzed reaction/ biological activity:
    • transcriptional regulator of many genes in response to thiol specific oxidative stress (transcription activator of trxA and trxB)
    • in addition, Spx inhibits transcription by binding to the C-terminal domain of the alpha subunit of RNAP (RpoA), disrupting complex formation between RNAP and certain transcriptional activator proteins like ResD and ComA
    • in response to thiol specific oxidative stress, Spx can also activate transcription, making it a general regulator that exerts both positive and negative control over transcription initiation
    • involved in competence regulation PubMed
  • Protein family: Spx subfamily (according to Swiss-Prot) Arsenate Reductase (ArsC) family, Spx subfamily
  • Paralogous protein(s): MgsR

Extended information on the protein

  • Kinetic information:
  • Domains: CXXC (10-13): Acts as a disulfide switch for the redox-sensitive transcriptional regulation of genes that function in thiol homeostasis.
  • Modification: Cysteine oxidation of the CXXC motif
  • Cofactor(s):
  • Effectors of protein activity:

Database entries

  • Structure: 1Z3E complex with C-terminal domain of RpoA NCBI
  • KEGG entry: [2]
  • E.C. number:

Additional information

Expression and regulation

  • Regulatory mechanism: transcription repression
  • Additional information:
    • post-translational control by ClpX-ClpP: Spx naturally contains a C-terminal sequence that resembles the SsrA tag and targets the protein for degradation. PubMed
    • proteolysis is enhanced by YjbH PubMed and counter-acted by YirB PubMed
    • the mRNA is substantially stabilized upon depletion of RNase Y (the half-life of the monocistronic spx mRNA increases from 1 to 6 min) PubMed

Biological materials

  • Mutant: ORB6781 (spc), ORB6876 (tet), available in Zuber lab, also available in the Stülke lab
  • Expression vector:
  • lacZ fusion:
  • GFP fusion:
  • two-hybrid system: B. pertussis adenylate cyclase-based bacterial two hybrid system (BACTH), available in Stülke lab
  • Antibody:

Labs working on this gene/protein

Peter Zuber, Oregon Health and Science University, USA Homepage

Richard Brennan, Houston, Texas, USA Homepage

Your additional remarks

References

Reviews

Additional reviews: PubMed

The Spx regulon

Structural analysis of Spx

Original Publications

Additional publications: PubMed

Lehnik-Habrink M, Schaffer M, Mäder U, Diethmaier C, Herzberg C, Stülke J  
RNA processing in Bacillus subtilis: identification of targets of the essential RNase Y. 
Mol Microbiol. 2011 81(6): 1459-1473. 
PubMed:21815947