Q46864 · MQSA_ECOLI
- ProteinAntitoxin MqsA
- GenemqsA
- StatusUniProtKB reviewed (Swiss-Prot)
- Organism
- Amino acids131 (go to sequence)
- Protein existenceEvidence at protein level
- Annotation score5/5
Function
function
Antitoxin component of a type II toxin-antitoxin (TA) system. Labile antitoxin that binds to the MqsR mRNA interferase toxin and neutralizes its endoribonuclease activity. Overexpression prevents MqsR-mediated cessation of cell growth and inhibition of cell proliferation. Initially reported to act as a cotranscription factor with MqsA (PubMed:19690171, PubMed:20105222).
Following further experiments, the MqsR-MqsA complex does not bind DNA and all reported data are actually due to a small fraction of free MqsA alone binding DNA. Addition of MqsR to a preformed MqsA-promoter DNA complex causes dissociation of the MqsA-DNA complex, probably causing derepression of MqsA-repressed transcripts (PubMed:23172222).
MqsA binds to 2 palindromes in the promoter region of the mqsRA operon activating its transcription. Binds to other promoters, inducing mcbR and spy and repressing cspD among others (PubMed:20105222).
Binds to and represses the rpoS promoter, the master stress regulator, resulting in decreased cyclic-di-GMP, reduced stress resistance, increased cell motility and decreased biofilm formation; in these experiments 5 TA systems are missing (lacks MazEF, RelEB, ChpB, YoeB-YefM, YafQ-DinJ) (PubMed:21516113).
An earlier study showed overexpression alone increases biofilm formation, perhaps by repressing cspD; in these experiments the 5 TA systems are present (PubMed:20105222).
Represses the csgD promoter. In the presence of stress, when this protein is degraded, the promoters it represses are derepressed, leading to biofilm formation (Probable). This TA system mediates cell growth during bile acid deoxycholate stress by degrading mRNA for probable deoxycholate-binding protein YgiS; bile acid detergents such as deoxycholate are important for host defense against bacterial growth in the gall bladder and duodenum (PubMed:25534751).
Following further experiments, the MqsR-MqsA complex does not bind DNA and all reported data are actually due to a small fraction of free MqsA alone binding DNA. Addition of MqsR to a preformed MqsA-promoter DNA complex causes dissociation of the MqsA-DNA complex, probably causing derepression of MqsA-repressed transcripts (PubMed:23172222).
MqsA binds to 2 palindromes in the promoter region of the mqsRA operon activating its transcription. Binds to other promoters, inducing mcbR and spy and repressing cspD among others (PubMed:20105222).
Binds to and represses the rpoS promoter, the master stress regulator, resulting in decreased cyclic-di-GMP, reduced stress resistance, increased cell motility and decreased biofilm formation; in these experiments 5 TA systems are missing (lacks MazEF, RelEB, ChpB, YoeB-YefM, YafQ-DinJ) (PubMed:21516113).
An earlier study showed overexpression alone increases biofilm formation, perhaps by repressing cspD; in these experiments the 5 TA systems are present (PubMed:20105222).
Represses the csgD promoter. In the presence of stress, when this protein is degraded, the promoters it represses are derepressed, leading to biofilm formation (Probable). This TA system mediates cell growth during bile acid deoxycholate stress by degrading mRNA for probable deoxycholate-binding protein YgiS; bile acid detergents such as deoxycholate are important for host defense against bacterial growth in the gall bladder and duodenum (PubMed:25534751).
Cofactor
Note: Binds 1 Zn2+ ion per subunit.
Temperature Dependence
The MqsR-MqsA complex is exceptionally thermostable with a Tm of 83.4 degress Celsius versus 48.1 degress Celsius for MqsR and 61.1 degress Celsius for MqsA.
Features
Showing features for binding site, dna binding.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Binding site | 3 | Zn2+ (UniProtKB | ChEBI); structural | ||||
Sequence: C | ||||||
Binding site | 6 | Zn2+ (UniProtKB | ChEBI); structural | ||||
Sequence: C | ||||||
Binding site | 37 | Zn2+ (UniProtKB | ChEBI); structural | ||||
Sequence: C | ||||||
Binding site | 40 | Zn2+ (UniProtKB | ChEBI); structural | ||||
Sequence: C | ||||||
DNA binding | 85-104 | H-T-H motif | ||||
Sequence: QKEASEIFGGGVNAFSRYEK |
GO annotations
Aspect | Term | |
---|---|---|
Cellular Component | toxin-antitoxin complex | |
Molecular Function | metal ion binding | |
Molecular Function | protein homodimerization activity | |
Molecular Function | sequence-specific DNA binding | |
Biological Process | regulation of DNA-templated transcription | |
Biological Process | single-species biofilm formation |
Keywords
- Molecular function
- Biological process
- Ligand
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended nameAntitoxin MqsA
Gene names
Organism names
- Organism
- Strains
- Taxonomic lineageBacteria > Pseudomonadota > Gammaproteobacteria > Enterobacterales > Enterobacteriaceae > Escherichia
Accessions
- Primary accessionQ46864
- Secondary accessions
Proteomes
Subcellular Location
UniProt Annotation
GO Annotation
Phenotypes & Variants
Disruption phenotype
Essential for growth, it cannot be disrupted (PubMed:16768798).
A double mqsR-mqsA deletion leads to increased rpoS mRNA levels, resulting in increased cyclic-di-GMP levels, increasing stress resistance, increased biofilm formation (PubMed:21516113).
The double mutant has increased metabolism and respiration in the presence of the bile acid deoxycholate and consequently grows less well. Decreases cell survival in the presence of 20% deoxycholate (PubMed:25534751).
A double mqsR-mqsA deletion leads to increased rpoS mRNA levels, resulting in increased cyclic-di-GMP levels, increasing stress resistance, increased biofilm formation (PubMed:21516113).
The double mutant has increased metabolism and respiration in the presence of the bile acid deoxycholate and consequently grows less well. Decreases cell survival in the presence of 20% deoxycholate (PubMed:25534751).
Features
Showing features for mutagenesis.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Mutagenesis | 61 | Decreases DNA-binding, decreases thermostability of MqsR-MqsA complex. | ||||
Sequence: R → A or D | ||||||
Mutagenesis | 97 | 50-fold reduction in DNA-binding. | ||||
Sequence: N → A | ||||||
Mutagenesis | 97-101 | Abolishes DNA-binding, including binding to the rpoS promoter. | ||||
Sequence: NAFSR → AAFSA | ||||||
Mutagenesis | 101 | 10-fold reduction in DNA-binding. | ||||
Sequence: R → A |
PTM/Processing
Features
Showing features for chain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Chain | PRO_0000149762 | 1-131 | Antitoxin MqsA | |||
Sequence: MKCPVCHQGEMVSGIKDIPYTFRGRKTVLKGIHGLYCVHCEESIMNKEESDAFMAQVKAFRASVNAETVAPEFIVKVRKKLSLTQKEASEIFGGGVNAFSRYEKGNAQPHPSTIKLLRVLDKHPELLNEIR |
Post-translational modification
Degraded in the presence of oxidative stress, maybe by the Lon and/or ClpX proteases.
Proteomic databases
Expression
Induction
Induced by amino acid starvation, glucose starvation and when translation is blocked. Induction is decreased in the absence of the Lon protease suggesting, by homology to other toxin-antitoxin systems, that Lon may degrade the MqsA antitoxin. Transcription is activated by MqsA (PubMed:20105222).
It has been suggested that MqsA represses its own operon (PubMed:19690171).
Not more induced in persister cells (PubMed:16768798).
A member of the mqsRA operon. This operon induced by ectopic expression of toxins RelE, HicA and YafQ but not by MazF or HicA (PubMed:23432955).
It has been suggested that MqsA represses its own operon (PubMed:19690171).
Not more induced in persister cells (PubMed:16768798).
A member of the mqsRA operon. This operon induced by ectopic expression of toxins RelE, HicA and YafQ but not by MazF or HicA (PubMed:23432955).
Interaction
Subunit
Homodimer. Crystallizes as a heterotetramer with MqsA, MqsR-MqsA2-MqsR (PubMed:20041169).
Purifies as a probable heterohexamer of 2 MqsR dimers and 1 MqsA dimer (PubMed:19690171).
Binds promoter DNA as a dimer (PubMed:21068382).
When the 2 dissociate the MsqR mRNA interferase becomes active
Purifies as a probable heterohexamer of 2 MqsR dimers and 1 MqsA dimer (PubMed:19690171).
Binds promoter DNA as a dimer (PubMed:21068382).
When the 2 dissociate the MsqR mRNA interferase becomes active
Binary interactions
Type | Entry 1 | Entry 2 | Number of experiments | Intact | |
---|---|---|---|---|---|
BINARY | Q46864 | infA P69222 | 2 | EBI-1120353, EBI-1120746 | |
BINARY | Q46864 | pldB P07000 | 2 | EBI-1120353, EBI-9134416 | |
BINARY | Q46864 | rbsR P0ACQ0 | 3 | EBI-1120353, EBI-1119646 | |
BINARY | Q46864 | rpmA P0A7L8 | 2 | EBI-1120353, EBI-546875 | |
BINARY | Q46864 | rpoE P0AGB6 | 2 | EBI-1120353, EBI-1129580 | |
BINARY | Q46864 | ybfE P0AAU7 | 2 | EBI-1120353, EBI-9138393 |
Protein-protein interaction databases
Structure
Family & Domains
Features
Showing features for domain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Domain | 74-127 | HTH cro/C1-type | ||||
Sequence: IVKVRKKLSLTQKEASEIFGGGVNAFSRYEKGNAQPHPSTIKLLRVLDKHPELL |
Domain
The Zn-binding N-terminal domain (residues 1-65) binds to the MqsR mRNA interferase toxin and makes contact with the DNA phosphate backbone, while the C-terminus (residues 70-131) binds the promoter in a sequence-specific manner. They are linked by a short flexible domain (PubMed:22789559).
Phylogenomic databases
Family and domain databases
Sequence
- Sequence statusComplete
- Length131
- Mass (Da)14,703
- Last updated1996-11-01 v1
- ChecksumAA26A2793AD84447
Keywords
- Technical term
Sequence databases
Nucleotide Sequence | Protein Sequence | Molecule Type | Status | |
---|---|---|---|---|
U28377 EMBL· GenBank· DDBJ | AAA69189.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
U00096 EMBL· GenBank· DDBJ | AAC76057.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
AP009048 EMBL· GenBank· DDBJ | BAE77077.1 EMBL· GenBank· DDBJ | Genomic DNA |