Spx

• 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
MW, pI	15,5 kDa, 7.80
Gene length, protein length	393 bp, 131 amino acids
Immediate neighbours	yjbC, yjbE
Gene sequence (+200bp)	Protein sequence
Genetic context This image was kindly provided by SubtiList

The gene

Basic information

• Coordinates: 1227010 - 1227402

Phenotypes of a mutant

Loss of up-regulation of the methionine sulfoxide reductase (mrsA-mrsB) 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

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.

• Protein family: 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:

• Interactions: YjbH-Spx PubMed, Spx-RpoA (C-terminal domain PubMed
• Localization:

Database entries

• Structure: complex with C-terminal domain of RpoA NCBI

• Swiss prot entry:

• KEGG entry: [2]

• E.C. number:

Expression and regulation

• Operon: yjbC-spx, spx

• Sigma factor: four promoters upstream of yjbC: SigW, SigB, SigX, and unknown sigma PubMed,

promoters upstream of spx: SigA, SigW PubMed, SigM PubMed

• Regulation: induced by stress (SigB) PubMed, Transcription is represed by PerR and YodB PubMed

• 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

Biological materials

• Mutant: ORB6781 (spc), ORB6876 (tet), available in Zuber 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

References

1. Höper et al. (2005) Comprehensive Characterization of the Contribution of Individual SigB-Dependent General Stress Genes to Stress Resistance of Bacillus subtilis. J. Bact. 187: 2810-2826 PubMed
2. Choi, S. Y., D. Reyes, M. Leelakriangsak, and P. Zuber. 2006. The global regulator Spx functions in the control of organosulfur metabolism in Bacillus subtilis. J. Bacteriol. 188:5741-5751. PubMed
3. Eiamphungporn, W., and J. D. Helmann. 2008. The Bacillus subtilis sigma(M) regulon and its contribution to cell envelope stress responses. Mol. Microbiol. 67:830-848. PubMed
4. Garg et al. 2009. The YjbH protein of Bacillus subtilis enhances ClpXP-catalyzed proteolysis of Spx. J. Bacteriol. 191: 1268-1277. PubMed
5. Jervis et al. 2007. SigM-responsive genes of Bacillus subtilis and their promoters. J. Bacteriol. 189: 4534-4538. PubMed
6. Larsson, J. T., A. Rogstam, and C. von Wachenfeldt. 2007. YjbH is a novel negative effector of the disulphide stress regulator, Spx, in Bacillus subtilis. Mol. Microbiol. 66:669-684. PubMed
7. Leelakriangsak, M., K. Kobayashi, and P. Zuber. 2007. Dual negative control of spx transcription initiation from the P3 promoter by repressors PerR and YodB in Bacillus subtilis. J. Bacteriol. 189:1736-1744. PubMed
8. Nakano, M. M., F. Hajarizadeh, Y. Zhu, and P. Zuber. 2001. Loss-of-function mutations in yjbD result in ClpX- and ClpP-independent competence development of Bacillus subtilis. Mol. Microbiol. 42:383-394.PubMed
9. Nakano, S., K. N. Erwin, M. Ralle, and P. Zuber. 2005. Redox-sensitive transcriptional control by a thiol/disulphide switch in the global regulator, Spx. Mol. Microbiol. 55:498-510. PubMed
10. Nakano, S., E. Küster-Schöck, A. D. Grossman, and P. Zuber. 2003. Spx dependent global transcriptional control is induced by thiol-specific oxidative stress in Bacillus subtilis. Proc. Natl. Acad. Sci. USA 100:13603-13608. PubMed
11. Nakano, S., M. M. Nakano, Y. Zhang, M. Leelakriangsak, and P. Zuber. 2003. A regulatory protein that interferes with activator-stimulated transcription in bacteria. Proc. Natl. Acad. Sci. USA 100:4233-4238. PubMed
12. Nakano, S., G. Zheng, M. M. Nakano, and P. Zuber. 2002. Multiple pathways of Spx (YjbD) proteolysis in Bacillus subtilis. J. Bacteriol. 184:3664-3670. PubMed
13. Newberry, K. J., S. Nakano, P. Zuber, and R. G. Brennan. 2005. 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. USA 102:15839-15844. PubMed
14. Petersohn, A., J. Bernhardt, U. Gerth, D. Hoper, T. Koburger, U. Volker, and M. Hecker. 1999. Identification of sigma(B)-dependent genes in Bacillus subtilis using a promoter consensus-directed search and oligonucleotide hybridization. J. Bacteriol. 181:5718-5724. PubMed
15. Reyes, D. Y. and P. Zuber. 2008. Activation of transcription initiation by Spx: formation of a transcription complex and identification of a cis-acting element required for transcriptional activation. Mol. Microbiol. 69:765-779. PubMed
16. Thackray, P. D., and A. Moir. 2003. 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. 185:3491-3498. PubMed
17. Zhang, Y., S. Nakano, S. Y. Choi, and P. Zuber. 2006. Mutational analysis of the Bacillus subtilis RNA polymerase alpha C-terminal domain supports the interference model of Spx-dependent repression. J. Bacteriol. 188:4300-4311. PubMed
18. Zhang, Y., and P. Zuber. 2007. Requirement of the zinc-binding domain of ClpX for Spx proteolysis in Bacillus subtilis and effects of disulfide stress on ClpXP activity. J. Bacteriol. 189:7669-7680. PubMed
19. Zuber, P. 2004. Spx-RNA polymerase interaction and global transcriptional control during oxidative stress. J. Bacteriol. 186:1911-1918. PubMed