StpA protein, for Suppressor of td phenotype A, is a nucleoid-associated multifunctional protein |CITS:| that acts as a transcriptional repressor |CITS:|, in chromosomal DNA packaging |CITS:[ 22187157]|, and as a chaperone |CITS:|.When StpA binds DNA, it is able to form a rigid filament, and thus the access to DNA is blocked |CITS:[ 22187157]|. This protein is negatively autoregulated |CITS:| and it is involved in the %Beta;-glucoside utilization systems |CITS:| and the homologous recombination and repair of bleomycin damage |CITS:|. Gueun%e'; et al. suggested that StpA may regulate the expression of a tributyltin-inducible operon |CITS:|. Currently, no inducer for this regulator has been reported in the literature. New genes may be identified by high-throughput analysis |CITS:|.
It is a DNA-binding protein with similarity to H-NS |CITS:|, and these two proteins can have similar functions |CITS:|. It has an approximately fivefold-greater affinity for DNA than H-NS and has a preference for curved DNA |CITS:|. This regulator binds curved DNA, in the promoter region, with AT-rich motifs, and StpA binds to sites that have poorly related sequences and it does not have a consensus sequence for the DNA binding.
Expression of stpA from a plasmid can complement an hns mutant phenotype and StpA is able to repress and activate a subset of H-NS-regulated genes, but their specific mechanisms remain to be determined |CITS:|.
A dominant negative form of StpA can disrupt H-NS activity and vice versa, and H-NS can interact with StpA at two distinct domains to form heterodimers in vitro; also there exists evidence that some of these proteins can form homodimers |CITS:|. For this reason, in the absence of H-NS the StpA protein is rapidly degraded in a Lon protease-dependent manner |CITS:|; protection from proteolytic degradation appears to be mediated by direct interaction between StpA and H-NS |CITS:|. On the other hand StpA may form heteromeric complexes with Hha and YdgT |CITS:|.Read more >
StpA consists of two structured domains which are separated by a protease-sensitive linker |CITS:|. The N-terminal domain is involved in the protein-protein interaction, while the purified C-terminal domain alone promotes annealing of RNA oligonucleotides and trans-splicing in vitro |CITS:|. Repression of the bglG operon by StpA occurs as a molecular adapter |CITS:| and only in the presence of the N-terminal H-NS protein domain, which comprises the core for dimerization |CITS:|.
StpA has RNA chaperone activity in vitro and in vivo, and the RNA chaperone activity of StpA is influenced by the structural stability of the RNA target molecule |CITS:|. StpA may destabilize the small regulatory RNA MicF |CITS:|.
|Connectivity class:||Local Regulator|
|Length:||405 bp / 134 aa|
|TU(s) encoding the TF:||
|Regulated gene(s)||bglB, bglF, bglG, fau, leuO, ssrS, stpA|
|Multifun term(s) of regulated gene(s)||
MultiFun Term (List of genes associated to the multifun term)
carbon compounds (3)
bglB, bglF, bglG
Transcription related (2)
posttranslational modification (1)
covalent modification, demodification, maturation (1)
Phosphotransferase Systems (PEP-dependent PTS) (1)
drug resistance/sensitivity (1)
transcriptional level (1)
RNA related (1)
nucleoproteins, basic proteins (1)
|Regulated operon(s)||bglGFB, leuO, ssrS-fau, stpA|
|First gene in the operon(s)||bglG, bglG, leuO, ssrS, ssrS, ssrS, ssrS, stpA|
|Simple and complex regulons|
|Simple and complex regulatory phrases||Regulatory phrase (List of promoters regulated by the phrase)|
|Functional conformation||Function||Promoter||Sigma factor||Central Rel-Pos||Distance to first Gene||Genes||Sequence||LeftPos||RightPos||Evidence (Confirmed, Strong, Weak)||References|
|StpA||repressor||bglGp||nd||nd||nd||bglG, bglF, bglB||nd||nd||[GEA]||, |
|StpA||repressor||ssrSp1||Sigma70||nd||nd||ssrS, fau||nd||nd||[BPP], [GEA]|||
|StpA||repressor||ssrSp2||Sigma38||nd||nd||ssrS, fau||nd||nd||[BPP], [GEA]|||
|Evolutionary conservation of regulatory elements|
 Venkatesh GR., Kembou Koungni FC., Paukner A., Stratmann T., Blissenbach B., Schnetz K., 2010, BglJ-RcsB heterodimers relieve repression of the Escherichia coli bgl operon by H-NS., J Bacteriol. 192(24):6456-64
 Stratmann T., Pul ¿¿., Wurm R., Wagner R., Schnetz K., 2012, RcsB-BglJ activates the Escherichia coli leuO gene, encoding an H-NS antagonist and pleiotropic regulator of virulence determinants., Mol Microbiol. 83(6):1109-23
 Neusser T., Gildehaus N., Wurm R., Wagner R., 2008, Studies on the expression of 6S RNA from E. coli: involvement of regulators important for stress and growth adaptation., Biol Chem. 389(3):285-97