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Description: 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

Name: spx
Locus: BSU11500BsubCyc
pI: 7.0
MW: 15.0 kDa
Protein length: 131 aaBLASTSequence
Gene length: 393 bpBLASTSequenceSequence + Flanks
Function: negative and positive regulator of many genes
Product: transcriptional regulator Spx
Essential: no
E.C. number:
Synonyms: yjbD
Databases: SubtiListKEGGUniProtExpression data browser

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), resistance against oxidative and electrophile stress

This gene is a member of the following regulons

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

The Spx regulon


  • 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 (msrA-msrB) operon in response to thiol specific oxidative stress, also loss of trxA and 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 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
  • Kinetic information


  • 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
  • Cofactors

    Effectors of protein activity


  • 1Z3E complex with C-terminal domain of RpoA NCBI
  • Localization

  • cytoplasm (according to Swiss-Prot)
  • Interactions

  • Spx-YjbH PubMed
  • Spx-RpoA (C-terminal domain) PubMed
  • Spx-ClpP/ClpX (degradation of Spx) PubMed
  • Additional information

    Expression and Regulation


  • yjbC-spx PubMed
  • spx PubMed
  • Sigma factor

  • four promoters upstream of yjbC: SigW, SigB, SigX PubMed, SigM PubMed
  • promoters upstream of spx: SigA, SigW PubMed, SigM PubMed
  • Regulation

  • induced by stress (SigB) PubMed
  • transcription is represed by PerR and YodB PubMed
  • repressed in the absence of hydrogen peroxide (PerR) PubMed
  • upregulated in response to enduracidin PubMed
  • Regulatory mechanism

  • transcription repression
  • PerR: transcription repression PubMed
  • 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
  • YjbH aggregates under stress conditions, resulting in the inability to bind to Spx, and therefore in stabilization of Spx, in contrast active soluble YjbH under non-stressed conditions targets Spx to degradation 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


  • MGNA-B151 (yjbD::erm), available at the NBRP B. subtilis, Japan
  • GPUG3 (spc), available in Ulf Gerths and Jörg Stülkes labs
  • GP1788 (spc), available in Jörg Stülkes lab
  • ORB6781 (spc), ORB6876 (tet), available in Zuber lab, also available in the Stülke lab
  • 1A917 ( spx::spec), PubMed, available at BGSC
  • 1A916 ( spx::tet), PubMed, available at BGSC
  • Expression vector

    lacZ fusion

    GFP fusion

    two-hybrid system

  • B. pertussis adenylate cyclase-based bacterial two hybrid system (BACTH), available in Stülke lab
  • FLAG-tag construct


    Labs working on this gene/protein

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


    Antelmann H, Helmann JD

    Thiol-based redox switches and gene regulation

    Antioxid Redox Signal. 2011 Mar 15;14(6):1049-63. doi: 10.1089/ars.2010.3400. Epub 2010 Oct 28. Review. PubMed PMID: 20626317; PubMed Central PMCID: PMC3113447.
    Zuber P

    Management of oxidative stress in Bacillus

    Annu Rev Microbiol. 2009;63:575-97. doi: 10.1146/annurev.micro.091208.073241. Review. PubMed PMID: 19575568.

    The Spx regulon

    Rochat T, Nicolas P, Delumeau O, Rabatinová A, Korelusová J, Leduc A, Bessières P, Dervyn E, Krásny L, Noirot P

    Genome-wide identification of genes directly regulated by the pleiotropic transcription factor Spx in Bacillus subtilis

    Nucleic Acids Res. 2012 Oct;40(19):9571-83. doi: 10.1093/nar/gks755. Epub 2012 Aug 16. PubMed PMID: 22904090; PubMed Central PMCID: PMC3479203.
    Erwin KN, Nakano S, Zuber P

    Sulfate-dependent repression of genes that function in organosulfur metabolism in Bacillus subtilis requires Spx

    J Bacteriol. 2005 Jun;187(12):4042-9. PubMed PMID: 15937167; PubMed Central PMCID: PMC1151713.
    Zuber P

    Spx-RNA polymerase interaction and global transcriptional control during oxidative stress

    J Bacteriol. 2004 Apr;186(7):1911-8. Review. PubMed PMID: 15028674; PubMed Central PMCID: PMC374421.
    Nakano S, Küster-Schöck E, Grossman AD, Zuber P

    Spx-dependent global transcriptional control is induced by thiol-specific oxidative stress in Bacillus subtilis

    Proc Natl Acad Sci U S A. 2003 Nov 11;100(23):13603-8. Epub 2003 Nov 3. PubMed PMID: 14597697; PubMed Central PMCID: PMC263860.

    Structural analysis of Spx

    Lin AA, Walthers D, Zuber P

    Residue substitutions near the redox center of Bacillus subtilis Spx affect RNA polymerase interaction, redox control, and Spx-DNA contact at a conserved cis-acting element

    J Bacteriol. 2013 Sep;195(17):3967-78. PubMed PMID: 23813734; PubMed Central PMCID: PMC3754600.
    Lamour V, Westblade LF, Campbell EA, Darst SA

    Crystal structure of the in vivo-assembled Bacillus subtilis Spx/RNA polymerase alpha subunit C-terminal domain complex

    J Struct Biol. 2009 Nov;168(2):352-6. doi: 10.1016/j.jsb.2009.07.001. Epub 2009 Jul 4. PubMed PMID: 19580872; PubMed Central PMCID: PMC2757488.
    Newberry KJ, Nakano S, Zuber P, Brennan RG

    Crystal structure of the Bacillus subtilis anti-alpha, global transcriptional regulator, Spx, in complex with the alpha C-terminal domain of RNA polymerase

    Proc Natl Acad Sci U S A. 2005 Nov 1;102(44):15839-44. Epub 2005 Oct 25. PubMed PMID: 16249335; PubMed Central PMCID: PMC1266077.

    Original Publications

    Al-Eryani Y, Ib Rasmussen M, Kjellström S, Højrup P, Emanuelsson C, von Wachenfeldt C

    Exploring structure and interactions of the bacterial adaptor protein YjbH by crosslinking mass spectrometry

    Proteins. 2016 Sep;84(9):1234-45. doi: 10.1002/prot.25072. Epub 2016 Jun 15. PubMed PMID: 27191337.
    Shiwa Y, Yoshikawa H, Tanaka T, Ogura M

    Bacillus subtilis degSU operon is regulated by the ClpXP-Spx regulated proteolysis system

    J Biochem. 2015 May;157(5):321-30. doi: 10.1093/jb/mvu076. Epub 2014 Nov 29. PubMed PMID: 25433860.
    Engman J, von Wachenfeldt C

    Regulated protein aggregation: a mechanism to control the activity of the ClpXP adaptor protein YjbH

    Mol Microbiol. 2015 Jan;95(1):51-63. doi: 10.1111/mmi.12842. Epub 2014 Nov 28. PubMed PMID: 25353645.
    Chan CM, Hahn E, Zuber P

    Adaptor bypass mutations of Bacillus subtilis spx suggest a mechanism for YjbH-enhanced proteolysis of the regulator Spx by ClpXP

    Mol Microbiol. 2014 Aug;93(3):426-38. doi: 10.1111/mmi.12671. Epub 2014 Jul 10. PubMed PMID: 24942655; PubMed Central PMCID: PMC4128009.
    Runde S, Molière N, Heinz A, Maisonneuve E, Janczikowski A, Elsholz AK, Gerth U, Hecker M, Turgay K

    The role of thiol oxidative stress response in heat-induced protein aggregate formation during thermotolerance in Bacillus subtilis

    Mol Microbiol. 2014 Mar;91(5):1036-52. doi: 10.1111/mmi.12521. Epub 2014 Jan 29. PubMed PMID: 24417481.
    Yang CK, Tai PC, Lu CD

    Time-related transcriptome analysis of B

    subtilis 168 during growth with glucose. Curr Microbiol. 2014 Jan;68(1):12-20. doi: 10.1007/s00284-013-0432-4. Epub 2013 Aug 10. PubMed PMID: 23934352.
    Gaballa A, Antelmann H, Hamilton CJ, Helmann JD

    Regulation of Bacillus subtilis bacillithiol biosynthesis operons by Spx

    Microbiology. 2013 Oct;159(Pt 10):2025-35. doi: 10.1099/mic.0.070482-0. Epub 2013 Jul 26. PubMed PMID: 23894131.
    Reder A, Höper D, Gerth U, Hecker M

    Contributions of individual σB-dependent general stress genes to oxidative stress resistance of Bacillus subtilis

    J Bacteriol. 2012 Jul;194(14):3601-10. doi: 10.1128/JB.00528-12. Epub 2012 May 11. PubMed PMID: 22582280; PubMed Central PMCID: PMC3393503.
    Lin AA, Zuber P

    Evidence that a single monomer of Spx can productively interact with RNA polymerase in Bacillus subtilis

    J Bacteriol. 2012 Apr;194(7):1697-707. doi: 10.1128/JB.06660-11. Epub 2012 Feb 3. PubMed PMID: 22307755; PubMed Central PMCID: PMC3302468.
    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 Sep;81(6):1459-73. doi: 10.1111/j.1365-2958.2011.07777.x. Epub 2011 Aug 4. PubMed PMID: 21815947.
    Kommineni S, Garg SK, Chan CM, Zuber P

    YjbH-enhanced proteolysis of Spx by ClpXP in Bacillus subtilis is inhibited by the small protein YirB (YuzO)

    J Bacteriol. 2011 May;193(9):2133-40. doi: 10.1128/JB.01350-10. Epub 2011 Mar 4. PubMed PMID: 21378193; PubMed Central PMCID: PMC3133067.
    Nakano MM, Lin A, Zuber CS, Newberry KJ, Brennan RG, Zuber P

    Promoter recognition by a complex of Spx and the C-terminal domain of the RNA polymerase alpha subunit

    PLoS One. 2010 Jan 13;5(1):e8664. doi: 10.1371/journal.pone.0008664. PubMed PMID: 20084284; PubMed Central PMCID: PMC2801614.
    Rukmana A, Morimoto T, Takahashi H, Giyanto, Ogasawara N

    Assessment of transcriptional responses of Bacillus subtilis cells to the antibiotic enduracidin, which interferes with cell wall synthesis, using a high-density tiling chip

    Genes Genet Syst. 2009 Aug;84(4):253-67. Erratum in: Genes Genet Syst. 2009 Oct;84(5):2 p following 395. PubMed PMID: 20057163.
    Garg SK, Kommineni S, Henslee L, Zhang Y, Zuber P

    The YjbH protein of Bacillus subtilis enhances ClpXP-catalyzed proteolysis of Spx

    J Bacteriol. 2009 Feb;191(4):1268-77. doi: 10.1128/JB.01289-08. Epub 2008 Dec 12. PubMed PMID: 19074380; PubMed Central PMCID: PMC2632004.
    Reyes DY, Zuber P

    Activation of transcription initiation by Spx: formation of transcription complex and identification of a Cis-acting element required for transcriptional activation

    Mol Microbiol. 2008 Aug;69(3):765-79. doi: 10.1111/j.1365-2958.2008.06330.x. PubMed PMID: 18687074; PubMed Central PMCID: PMC2758557.
    You C, Sekowska A, Francetic O, Martin-Verstraete I, Wang Y, Danchin A

    Spx mediates oxidative stress regulation of the methionine sulfoxide reductases operon in Bacillus subtilis

    BMC Microbiol. 2008 Jul 28;8:128. doi: 10.1186/1471-2180-8-128. PubMed PMID: 18662407; PubMed Central PMCID: PMC2518928.
    Hochgräfe F, Wolf C, Fuchs S, Liebeke M, Lalk M, Engelmann S, Hecker M

    Nitric oxide stress induces different responses but mediates comparable protein thiol protection in Bacillus subtilis and Staphylococcus aureus

    J Bacteriol. 2008 Jul;190(14):4997-5008. doi: 10.1128/JB.01846-07. Epub 2008 May 16. PubMed PMID: 18487332; PubMed Central PMCID: PMC2447014.
    Eiamphungporn W, Helmann JD

    The Bacillus subtilis sigma(M) regulon and its contribution to cell envelope stress responses

    Mol Microbiol. 2008 Feb;67(4):830-48. doi: 10.1111/j.1365-2958.2007.06090.x. Epub 2008 Jan 2. PubMed PMID: 18179421; PubMed Central PMCID: PMC3025603.
    Larsson JT, Rogstam A, von Wachenfeldt C

    YjbH is a novel negative effector of the disulphide stress regulator, Spx, in Bacillus subtilis

    Mol Microbiol. 2007 Nov;66(3):669-84. Epub 2007 Oct 1. PubMed PMID: 17908206.
    Zhang Y, Zuber P

    Requirement of the zinc-binding domain of ClpX for Spx proteolysis in Bacillus subtilis and effects of disulfide stress on ClpXP activity

    J Bacteriol. 2007 Nov;189(21):7669-80. Epub 2007 Sep 7. PubMed PMID: 17827297; PubMed Central PMCID: PMC2168722.
    Jervis AJ, Thackray PD, Houston CW, Horsburgh MJ, Moir A

    SigM-responsive genes of Bacillus subtilis and their promoters

    J Bacteriol. 2007 Jun;189(12):4534-8. Epub 2007 Apr 13. PubMed PMID: 17434969; PubMed Central PMCID: PMC1913368.
    Jervis AJ, Thackray PD, Houston CW, Horsburgh MJ, Moir A

    SigM-responsive genes of Bacillus subtilis and their promoters

    J Bacteriol. 2007 Jun;189(12):4534-8. Epub 2007 Apr 13. PubMed PMID: 17434969; PubMed Central PMCID: PMC1913368.
    Leelakriangsak M, Kobayashi K, Zuber P

    Dual negative control of spx transcription initiation from the P3 promoter by repressors PerR and YodB in Bacillus subtilis

    J Bacteriol. 2007 Mar;189(5):1736-44. Epub 2006 Dec 8. PubMed PMID: 17158660; PubMed Central PMCID: PMC1855716.
    Leelakriangsak M, Kobayashi K, Zuber P

    Dual negative control of spx transcription initiation from the P3 promoter by repressors PerR and YodB in Bacillus subtilis

    J Bacteriol. 2007 Mar;189(5):1736-44. Epub 2006 Dec 8. PubMed PMID: 17158660; PubMed Central PMCID: PMC1855716.
    Choi SY, Reyes D, Leelakriangsak M, Zuber P

    The global regulator Spx functions in the control of organosulfur metabolism in Bacillus subtilis

    J Bacteriol. 2006 Aug;188(16):5741-51. PubMed PMID: 16885442; PubMed Central PMCID: PMC1540065.
    Zhang Y, Nakano S, Choi SY, Zuber P

    Mutational analysis of the Bacillus subtilis RNA polymerase alpha C-terminal domain supports the interference model of Spx-dependent repression

    J Bacteriol. 2006 Jun;188(12):4300-11. PubMed PMID: 16740936; PubMed Central PMCID: PMC1482945.
    Höper D, Völker U, Hecker M

    Comprehensive characterization of the contribution of individual SigB-dependent general stress genes to stress resistance of Bacillus subtilis

    J Bacteriol. 2005 Apr;187(8):2810-26. PubMed PMID: 15805528; PubMed Central PMCID: PMC1070366.
    Nakano S, Erwin KN, Ralle M, Zuber P

    Redox-sensitive transcriptional control by a thiol/disulphide switch in the global regulator, Spx

    Mol Microbiol. 2005 Jan;55(2):498-510. PubMed PMID: 15659166.
    Thackray PD, Moir A

    SigM, an extracytoplasmic function sigma factor of Bacillus subtilis, is activated in response to cell wall antibiotics, ethanol, heat, acid, and superoxide stress

    J Bacteriol. 2003 Jun;185(12):3491-8. PubMed PMID: 12775685; PubMed Central PMCID: PMC156226.
    Nakano S, Nakano MM, Zhang Y, Leelakriangsak M, Zuber P

    A regulatory protein that interferes with activator-stimulated transcription in bacteria

    Proc Natl Acad Sci U S A. 2003 Apr 1;100(7):4233-8. Epub 2003 Mar 17. PubMed PMID: 12642660; PubMed Central PMCID: PMC153076.
    Nakano S, Zheng G, Nakano MM, Zuber P

    Multiple pathways of Spx (YjbD) proteolysis in Bacillus subtilis

    J Bacteriol. 2002 Jul;184(13):3664-70. PubMed PMID: 12057962; PubMed Central PMCID: PMC135134.
    Nakano MM, Hajarizadeh F, Zhu Y, Zuber P

    Loss-of-function mutations in yjbD result in ClpX- and ClpP-independent competence development of Bacillus subtilis

    Mol Microbiol. 2001 Oct;42(2):383-94. PubMed PMID: 11703662.
    Antelmann H, Scharf C, Hecker M

    Phosphate starvation-inducible proteins of Bacillus subtilis: proteomics and transcriptional analysis

    J Bacteriol. 2000 Aug;182(16):4478-90. PubMed PMID: 10913081; PubMed Central PMCID: PMC94619.
    Petersohn A, Bernhardt J, Gerth U, Höper D, Koburger T, Völker U, Hecker M

    Identification of sigma(B)-dependent genes in Bacillus subtilis using a promoter consensus-directed search and oligonucleotide hybridization

    J Bacteriol. 1999 Sep;181(18):5718-24. PubMed PMID: 10482513; PubMed Central PMCID: PMC94092.
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