|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:|. 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:|.
AsnC belongs to the AsnC family of regulatory proteins whose members are widely distributed in archaea and bacteria |CITS:|. It has been postulated that AsnC is very ascient; it appears that it was present before the divergence of archea and bacteria |CITS:|. 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:|.
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:|. 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:[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:|.
The transcription of asnC sometimes traverses the origin of replication and continues into gidA, possibly explaining the effect on gidA expression |CITS:[ 2836709]|. Sometimes the transcription of asnC ends at a terminator located downstream of this gene or by the DnaA protein that binds to a DnaA box blocking the transcribing RNA polymerase |CITS:|.Read more >
Expression of asnC is regulated by nitrogen availability; under nitrogen-limiting conditions, Nac represses asnC |CITS:|.
|Sensing class:||Sensing external and internal signals|
|Connectivity class:||Local Regulator|
|Length:||459 bp / 152 aa|
|TU(s) encoding the TF:||
|Regulated gene(s)||asnA, asnC, mioC, mnmG|
|Multifun term(s) of regulated gene(s)||
MultiFun Term (List of genes associated to the multifun term)
Transcription related (1)
asnCRead more >
|Regulated operon(s)||asnA, asnC-mioC-mnmG-rsmG|
|First gene in the operon(s)||asnA, asnC, asnC, asnC|
|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|
|AsnC||repressor||asnCp||Sigma70||-85.5||-113.5||asnC, mioC, mnmG||
|AsnC||repressor||asnCp||Sigma70||-54.5||-82.5||asnC, mioC, mnmG||
|AsnC||repressor||asnCp||Sigma70||-22.5||-50.5||asnC, mioC, mnmG||
|AsnC||repressor||asnCp||Sigma70||12.5||-16.5||asnC, mioC, mnmG||
|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
|Evolutionary conservation of regulatory elements|