SubtiBank SubtiBank
spx [Tue Dec 13 2016 11:16:31 GMT+0100 (CET)]
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spx [Tue Dec 13 2016 11:16:31 GMT+0100 (CET)]

transcriptional regulator Spx, involved in regulation of many genes, important for the prevention of protein aggregation during severe heat stress, required for protection against paraquat stress
15.00 kDa
negative and positive regulator of many genes
transcriptional regulator Spx

Genomic Context



  • [category|SW 3|Information processing] → [category|SW 3.4|Regulation of gene expression] → [category|SW 3.4.2|Transcription factors and their control] → [category|SW|Transcription factors/ other]
  • [category|SW 4|Lifestyles] → [category|SW 4.3|Coping with stress] → [category|SW 4.3.1|General stress proteins (controlled by SigB)]
  • [category|SW 4|Lifestyles] → [category|SW 4.3|Coping with stress] → [category|SW 4.3.2|Cell envelope stress proteins (controlled by SigM, V, W, X, Y)]
  • [category|SW 4|Lifestyles] → [category|SW 4.3|Coping with stress] → [category|SW 4.3.8|Resistance against oxidative and electrophile stress]
  • [SW|Categories] containing this gene/protein

  • [SW|transcription factors and their control], [SW|general stress proteins (controlled by SigB)], [SW|cell envelope stress proteins (controlled by SigM, V, W, X, Y)], [SW|resistance against oxidative and electrophile stress]
  • This gene is a member of the following [SW|regulons]

  • [SW|PerR regulon], [SW|SigB regulon], [SW|SigM regulon], [SW|SigW regulon], [SW|SigX regulon]
  • Gene

    Coordinates on the chromosome (coding sequence)
    1,227,697 -> 1,228,092

    Phenotypes of a mutant

  • Loss of up-regulation of the methionine sulfoxide reductase (''[protein|search|msrA]-[protein|search|msrB]'') operon in response to thiol specific oxidative stress, also loss of ''[protein|search|trxA]'' and ''[protein|search|trxB]'' upregulation in response to thiol specific oxidative stress.
  • The protein

    Catalyzed reaction/ biological activity

  • transcriptional regulator of many genes in response to thiol specific oxidative stress (transcription activator of'' [protein|search|trxA]'' and ''[protein|search|trxB]'')
  • in addition, Spx inhibits transcription by binding to the C-terminal domain of the alpha subunit of RNAP ([protein|search|RpoA]), disrupting complex formation between RNAP and certain transcriptional activator proteins like [protein|search|ResD] and [protein|search|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|11703662]
  • Protein family

  • Spx subfamily (according to Swiss-Prot) Arsenate Reductase (ArsC) family, Spx subfamily
  • Paralogous protein(s)

  • [protein|search|MgsR]
  • [SW|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
  • Structure

  • [PDB|1Z3E] complex with C-terminal domain of [protein|search|RpoA] [ NCBI]
  • [SW|Localization]

  • cytoplasm (according to Swiss-Prot)
  • [SW|Interactions]

  • [protein|search|Spx]-[protein|search|YjbH] [Pubmed|19074380]
  • [protein|search|Spx]-[protein|search|RpoA] (C-terminal domain) [Pubmed|12642660,22307755]
  • [protein|search|Spx]-[protein|search|ClpP]/[protein|search|ClpX] (degradation of [protein|search|Spx]) [Pubmed|17827297]
  • Expression and Regulation


  • ''[protein|search|yjbC]-[protein|search|spx]'' [Pubmed|10913081]
  • ''[protein|search|spx]'' [Pubmed|10913081]
  • [SW|Sigma factor]

  • four promoters upstream of ''[protein|search|yjbC]'': [protein|search|SigW], [protein|search|SigB], [protein|search|SigX] [ PubMed], [protein|search|SigM] [Pubmed|17434969]
  • promoters upstream of ''spx'': [protein|search|SigA], [protein|search|SigW] [ PubMed], [protein|search|SigM] [Pubmed|17434969]
  • Regulation

  • induced by stress ([protein|search|SigB]) [Pubmed|15805528]
  • transcription is represed by [protein|search|PerR] and [SW|YodB ] [Pubmed|17158660]
  • repressed in the absence of hydrogen peroxide ([protein|search|PerR]) [Pubmed|17158660]
  • upregulated in response to enduracidin [Pubmed|20057163]
  • Regulatory mechanism

  • transcription repression
  • [protein|search|PerR]: transcription repression [Pubmed|17158660]
  • Additional information

  • post-translational control by [protein|search|ClpX]-[protein|search|ClpP]: Spx naturally contains a C-terminal sequence that resembles the [protein|search|SsrA] tag and targets the protein for degradation. [ PubMed]
  • proteolysis is enhanced by [protein|search|YjbH] [ PubMed] and counter-acted by [protein|search|YirB] [PubMed|21378193]
  • [protein|search|YjbH] aggregates under stress conditions, resulting in the inability to bind to [protein|search|Spx], and therefore in stabilization of [protein|search|Spx], in contrast active soluble [protein|search|YjbH] under non-stressed conditions targets [protein|search|Spx] to degradation [PubMed|25353645]
  • the mRNA is substantially stabilized upon depletion of [Rny|search|RNase Y] (the half-life of the monocistronic 'spx' mRNA increases from 1 to 6 min) [PubMed|21815947]
  • Biological materials


  • MGNA-B151 (yjbD::erm), available at the [ NBRP B. subtilis, Japan]
  • GPUG3 (spc), available in [SW|Ulf Gerth]s and [SW|Jörg Stülke]s labs
  • ORB6781 (spc), ORB6876 (tet), available in [SW|Zuber] lab, also available in the [SW|Stülke] lab
  • 1A917 ( ''spx''::''spec''), [Pubmed|21949854], available at [ BGSC]
  • 1A916 ( ''spx''::''tet''), [Pubmed|21949854], available at [ BGSC]
  • two-hybrid system

  • ''B. pertussis'' adenylate cyclase-based bacterial two hybrid system ([SW|BACTH]), available in [SW|Stülke] lab
  • Labs working on this gene/protein

  • [SW|Peter Zuber], Oregon Health and Science University, USA
  • [ Homepage]
  • [SW|Richard Brennan], Houston, Texas, USA [ Homepage]
  • References


  • 19575568,20626317
  • The [SW|Spx regulon]

  • 15937167,14597697,15028674,22904090
  • Structural analysis of Spx

  • 19580872,16249335,23813734
  • Original Publications

  • 21378193,22307755,18487332,17908206,17434969,17158660,19074380,15805528,18662407,16885442,18179421,17434969,17908206,17158660,11703662,15659166,12642660,12057962,10482513,18687074,12775685,16740936,17827297,20084284,20057163,10913081,21815947,23894131,23934352,22582280,24417481,24942655,25353645,25433860,27191337