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AsnC DNA-binding transcriptional dual regulator

Synonyms: AsnC-L-asparagine, AsnC
AsnC is a transcriptional regulator that activates the expression of asnA, a gene involved in the synthesis of asparagine |CITS:[2864330][3909107]|. However, when asparagine is present the activation of asnA is turned off. On the other hand, AsnC is negatively autoregulated, but the presence of asparagine does not affect this regulation |CITS:[2864330]|.
AsnC belongs to the AsnC family of regulatory proteins whose members are widely distributed in archaea and bacteria |CITS:[11523004]|. It has been postulated that AsnC is very ascient; it appears that it was present before the divergence of archea and bacteria |CITS:[11523004]|. This protein has a DNA-binding domain with a helix-turn-helix motif in the N terminus and an effector-binding C-terminal domain |CITS:[16528101]|.
A crystal structure of AsnC complexed with the ligand l-asparagine has been solved at 2.4-Å resolution. The crystal structure shows an octamer with l-asparagine bound in a cleft at the interface between dimers; however, the octamer is formed in an l-asparagine-independent manner |CITS:[16528101]|. The octamer is composed of four dimers, each of which appears to recognize and bind an inverted repeat DNA sequence of 5 bp separated by 3 bp that are usually T or A base pairs. There are four AsnC sites in the divergent regulatory regions of asnA and asnC, and they are separated by 18 bp |CITS:[16528101][Suzuki03]|.
The replication origin, oriC, is located between the mioC and gidA genes, and the asnC gene is immediately upstream of mioC in the genome |CITS:[2864330]|.
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Transcription factor      
TF conformation(s):
Name Conformation Type TF-Effector Interaction Type Apo/Holo Conformation Evidence (Confirmed, Strong, Weak) References
AsnC Functional   Apo [IPI] [1]
AsnC-L-asparagine Non-Functional Allosteric Holo [IPI] [1]
Evolutionary Family: AsnC
Sensing class: Sensing external and internal signals
Connectivity class: Local Regulator
Gene name: asnC
  Genome position: 3926545-3927003
  Length: 459 bp / 152 aa
Operon name: asnC-mioC-mnmG-rsmG
TU(s) encoding the TF:
Transcription unit        Promoter

Regulated gene(s) asnA, asnC, mioC, mnmG
Multifun term(s) of regulated gene(s) MultiFun Term (List of genes associated to the multifun term)
asparagine (2)
Transcription related (1)
activator (1)
repressor (1)
regulon (1)
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Regulated operon(s) asnA, asnC-mioC-mnmG-rsmG
First gene in the operon(s) asnA, asnC, asnC, asnC
Simple and complex regulons AsnC
Simple and complex regulatory phrases Regulatory phrase (List of promoters regulated by the phrase)

Transcription factor binding sites (TFBSs) arrangements       

  Functional conformation Function Promoter Sigma factor Central Rel-Pos Distance to first Gene Genes Sequence LeftPos RightPos Evidence (Confirmed, Strong, Weak) References
  AsnC activator asnAp Sigma70 -109.5 -135.5 asnA
3927013 3927026 [GEA] [2]
  AsnC activator asnAp Sigma70 -75.5 -101.5 asnA
3927047 3927060 [GEA] [2]
  AsnC activator asnAp Sigma70 -43.5 -69.5 asnA
3927079 3927092 [GEA] [3]
  AsnC activator asnAp Sigma70 -12.5 -38.5 asnA
3927110 3927123 [GEA] [2]
  AsnC repressor asnCp Sigma70 -85.5 -113.5 asnC, mioC, mnmG
3927110 3927123 [GEA] [2]
  AsnC repressor asnCp Sigma70 -54.5 -82.5 asnC, mioC, mnmG
3927079 3927092 [GEA] [3]
  AsnC repressor asnCp Sigma70 -22.5 -50.5 asnC, mioC, mnmG
3927047 3927060 [GEA] [2]
  AsnC repressor asnCp Sigma70 12.5 -16.5 asnC, mioC, mnmG
3927013 3927026 [GEA] [2]

Alignment and PSSM for AsnC TFBSs    

Aligned TFBS of AsnC   

Position weight matrix (PWM).   
A	0	0	1	0	2	1	0	0	4	3	0	0	4
C	0	0	0	0	0	2	0	0	0	0	0	2	0
G	0	1	0	0	2	0	1	3	0	0	0	2	0
T	4	3	3	4	0	1	3	1	0	1	4	0	0

PWM logo   


Evolutionary conservation of regulatory elements    
     Note: Evolutionary conservation of regulatory interactions and promoters is limited to gammaproteobacteria.
TF-target gene evolutionary conservation
Promoter-target gene evolutionary conservation


 [IPI] Inferred from physical interaction

 [GEA] Gene expression analysis


 [1] 16528101., null, null, null

 [2] Kolling R., Lother H., 1985, AsnC: an autogenously regulated activator of asparagine synthetase A transcription in Escherichia coli., J Bacteriol. 164(1):310-5

 [3] Tobia AJ., Couri D., Sagone A., 1985, The effects of the quinone type drugs on hydroxyl radical (OH.) production by rat liver microsomes., J Toxicol Environ Health. 15(2):265-77