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Entry version 124 (07 Apr 2021)
Sequence version 1 (01 Nov 1996)
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mRNA interferase toxin MqsR



Escherichia coli (strain K12)
Reviewed-Annotation score:

Annotation score:5 out of 5

<p>The annotation score provides a heuristic measure of the annotation content of a UniProtKB entry or proteome. This score <strong>cannot</strong> be used as a measure of the accuracy of the annotation as we cannot define the 'correct annotation' for any given protein.<p><a href='/help/annotation_score' target='_top'>More...</a></p>
-Experimental evidence at protein leveli <p>This indicates the type of evidence that supports the existence of the protein. Note that the 'protein existence' evidence does not give information on the accuracy or correctness of the sequence(s) displayed.<p><a href='/help/protein_existence' target='_top'>More...</a></p>

<p>This section provides any useful information about the protein, mostly biological knowledge.<p><a href='/help/function_section' target='_top'>More...</a></p>Functioni

Toxic component of a type II toxin-antitoxin (TA) system. Plays a significant role in the control of biofilm formation and induction of persister cells in the presence of antibiotics. An mRNA interferase which has been reported to be translation-independent (PubMed:19690171, PubMed:19943910, PubMed:23289863). It has also been reported to be translation-dependent (PubMed:20041169). Cleavage has been reported to occur on either side of G in the sequence GCU (PubMed:19690171). Also reported to cleave after C in GC(A/U) sequences (PubMed:19943910). There are only 14 genes in E.coli W3110 (and probably also MG1655) that do not have a GCU sequence and thus are resistant to the mRNA interferase activity; among these is the gene for toxin GhoT. Overexpression of MqsR causes cessation of cell growth and inhibits cell proliferation via inhibition of translation as well as increasing persister cell formation; these effects are overcome by concomitant or subsequent expression of antitoxin MqsA. Cross-talk can occur between different TA systems. Ectopic expression of this toxin induces transcription of the relBEF TA system operon with specific cleavage of the relBEF mRNA produced (PubMed:23432955). Regulates the expression of GhoT/GhoS, a type V TA system (PubMed:23289863). Persistence depends on toxin GhoT activity, which MqsR controls at the post-transcriptional level by selectively degrading the antitoxin ghoS segment of the ghoST mRNA (PubMed:23289863). Persister cells exhibit antibiotic tolerance without genetic change. mRNA interferases play a role in bacterial persistence to antibiotics; overexpression of this protein induces persisters resistant to coiprofloxacin and ampicillin (PubMed:21788497). Overexpression leads to a dramatic increase in tolerance to the antibiotic ofloxacin. 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).7 Publications
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. Does not bind DNA in the presence or absence of MqsA (PubMed:23172222).3 Publications

<p>This subsection of the 'Function' section describes biophysical and chemical properties, such as maximal absorption, kinetic parameters, pH dependence, redox potentials and temperature dependence.<p><a href='/help/biophysicochemical_properties' target='_top'>More...</a></p>Temperature dependencei

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.1 Publication

<p>The <a href="">Gene Ontology (GO)</a> project provides a set of hierarchical controlled vocabulary split into 3 categories:<p><a href='/help/gene_ontology' target='_top'>More...</a></p>GO - Molecular functioni

  • endoribonuclease activity Source: EcoCyc

GO - Biological processi

<p>UniProtKB Keywords constitute a <a href="">controlled vocabulary</a> with a hierarchical structure. Keywords summarise the content of a UniProtKB entry and facilitate the search for proteins of interest.<p><a href='/help/keywords' target='_top'>More...</a></p>Keywordsi

Molecular functionEndonuclease, Hydrolase, Nuclease
Biological processQuorum sensing, Stress response, Toxin-antitoxin system, Transcription, Transcription regulation

Enzyme and pathway databases

BioCyc Collection of Pathway/Genome Databases


<p>This section provides information about the protein and gene name(s) and synonym(s) and about the organism that is the source of the protein sequence.<p><a href='/help/names_and_taxonomy_section' target='_top'>More...</a></p>Names & Taxonomyi

<p>This subsection of the <a href="">Names and taxonomy</a> section provides an exhaustive list of all names of the protein, from commonly used to obsolete, to allow unambiguous identification of a protein.<p><a href='/help/protein_names' target='_top'>More...</a></p>Protein namesi
Recommended name:
mRNA interferase toxin MqsR1 Publication (EC:3.1.-.-)
Alternative name(s):
Endoribonuclease MqsR
Motility quorum-sensing regulator MqsR1 Publication
Toxin MqsR
<p>This subsection of the <a href="">Names and taxonomy</a> section indicates the name(s) of the gene(s) that code for the protein sequence(s) described in the entry. Four distinct tokens exist: 'Name', 'Synonyms', 'Ordered locus names' and 'ORF names'.<p><a href='/help/gene_name' target='_top'>More...</a></p>Gene namesi
Name:mqsR1 Publication
Ordered Locus Names:b3022, JW2990
<p>This subsection of the <a href="">Names and taxonomy</a> section provides information on the name(s) of the organism that is the source of the protein sequence.<p><a href='/help/organism-name' target='_top'>More...</a></p>OrganismiEscherichia coli (strain K12)
<p>This subsection of the <a href="">Names and taxonomy</a> section shows the unique identifier assigned by the NCBI to the source organism of the protein. This is known as the 'taxonomic identifier' or 'taxid'.<p><a href='/help/taxonomic_identifier' target='_top'>More...</a></p>Taxonomic identifieri83333 [NCBI]
<p>This subsection of the <a href="">Names and taxonomy</a> section contains the taxonomic hierarchical classification lineage of the source organism. It lists the nodes as they appear top-down in the taxonomic tree, with the more general grouping listed first.<p><a href='/help/taxonomic_lineage' target='_top'>More...</a></p>Taxonomic lineageiBacteriaProteobacteriaGammaproteobacteriaEnterobacteralesEnterobacteriaceaeEscherichia
<p>This subsection of the <a href="">Names and taxonomy</a> section is present for entries that are part of a <a href="">proteome</a>, i.e. of a set of proteins thought to be expressed by organisms whose genomes have been completely sequenced.<p><a href='/help/proteomes_manual' target='_top'>More...</a></p>Proteomesi
  • UP000000318 <p>A UniProt <a href="">proteome</a> can consist of several components.<br></br>The component name refers to the genomic component encoding a set of proteins.<p><a href='/help/proteome_component' target='_top'>More...</a></p> Componenti: Chromosome
  • UP000000625 Componenti: Chromosome

<p>This section provides information on the disease(s) and phenotype(s) associated with a protein.<p><a href='/help/pathology_and_biotech_section' target='_top'>More...</a></p>Pathology & Biotechi

<p>This subsection of the 'Pathology and Biotech' section describes the in vivo effects caused by ablation of the gene (or one or more transcripts) coding for the protein described in the entry. This includes gene knockout and knockdown, provided experiments have been performed in the context of a whole organism or a specific tissue, and not at the single-cell level.<p><a href='/help/disruption_phenotype' target='_top'>More...</a></p>Disruption phenotypei

No loss of ability to form persister cells in MG1655, represses persister cell formation in BW25113. Deletion decreases biofilm formation in LB medium (PubMed:16352847). Deletion has also been shown to increase biofilm formation (PubMed:20105222). Deletion at 48h, in flow cells, leads to a reduction in biomass, substratum coverage and changes the biofilm architecture from a 54 micron thick film with microcolonies to one with nearly no biomass and only a few colonies remaining. Deletion abolishes motility. 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). mRNA interferases play a role in bacterial persistence to antibiotics; as 10 mRNA interferases are successively deleted reduced levels of persisters are generated (PubMed:21788497).7 Publications


Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the <a href="">'Pathology and Biotech'</a> section describes the effect of the experimental mutation of one or more amino acid(s) on the biological properties of the protein.<p><a href='/help/mutagen' target='_top'>More...</a></p>Mutagenesisi55Y → A: No change in toxicity. 1 Publication1
Mutagenesisi56K → A: Loss of toxicity. 1 Publication1
Mutagenesisi58M → A: No change in toxicity. 1 Publication1
Mutagenesisi68Q → A: Loss of toxicity. 1 Publication1
Mutagenesisi72R → A: No change in toxicity. 1 Publication1
Mutagenesisi81Y → A: Loss of toxicity. 1 Publication1
Mutagenesisi96K → A: Loss of toxicity. 1 Publication1

<p>This section describes post-translational modifications (PTMs) and/or processing events.<p><a href='/help/ptm_processing_section' target='_top'>More...</a></p>PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the 'PTM / Processing' section describes the extent of a polypeptide chain in the mature protein following processing or proteolytic cleavage.<p><a href='/help/chain' target='_top'>More...</a></p>ChainiPRO_00001694111 – 98mRNA interferase toxin MqsRAdd BLAST98

Proteomic databases

PaxDb, a database of protein abundance averages across all three domains of life


PRoteomics IDEntifications database


<p>This section provides information on the expression of a gene at the mRNA or protein level in cells or in tissues of multicellular organisms.<p><a href='/help/expression_section' target='_top'>More...</a></p>Expressioni

<p>This subsection of the 'Expression' section reports the experimentally proven effects of inducers and repressors (usually chemical compounds or environmental factors) on the level of protein (or mRNA) expression (up-regulation, down-regulation, constitutive expression).<p><a href='/help/induction' target='_top'>More...</a></p>Inductioni

Induced by amino acid starvation, glucose starvation and when translation is blocked. Also induced by nalidixic acid, azolocillin and H2O2 (PubMed:23289863). It has been suggested that MqsA represses its own operon (PubMed:19690171). 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). A member of the mqsRA operon. Most highly induced gene in persister cells (PubMed:16768798). Degrades its own transcript (PubMed:23172222). This operon induced by ectopic expression of toxins RelE, HicA and YafQ but not by MazF or HicA (PubMed:23432955).1 Publication5 Publications

<p>This section provides information on the quaternary structure of a protein and on interaction(s) with other proteins or protein complexes.<p><a href='/help/interaction_section' target='_top'>More...</a></p>Interactioni

<p>This subsection of the <a href="">'Interaction'</a> section provides information about the protein quaternary structure and interaction(s) with other proteins or protein complexes (with the exception of physiological receptor-ligand interactions which are annotated in the <a href="">'Function'</a> section).<p><a href='/help/subunit_structure' target='_top'>More...</a></p>Subunit structurei

Might be a dimer (PubMed:19690171). Also reported to be a monomer (PubMed:23172222). Crystallizes as a heterotetramer with MqsA, MqsR-MqsA2-MqsR (PubMed:20041169). Purifies as a possible heterohexamer of 2 MqsR dimers and 1 MqsA dimer (PubMed:19690171). When the 2 dissociate the MsqR mRNA interferase becomes active.

3 Publications

Protein-protein interaction databases

The Biological General Repository for Interaction Datasets (BioGRID)

4260831, 22 interactors

ComplexPortal: manually curated resource of macromolecular complexes

CPX-1084, MqsRA toxin-antitoxin complex

Protein interaction database and analysis system

Q46865, 10 interactors

STRING: functional protein association networks


<p>This section provides information on the tertiary and secondary structure of a protein.<p><a href='/help/structure_section' target='_top'>More...</a></p>Structurei

Secondary structure

Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details

3D structure databases

SWISS-MODEL Repository - a database of annotated 3D protein structure models


Database of comparative protein structure models


Protein Data Bank in Europe - Knowledge Base


<p>This section provides information on sequence similarities with other proteins and the domain(s) present in a protein.<p><a href='/help/family_and_domains_section' target='_top'>More...</a></p>Family & Domainsi

Phylogenomic databases

evolutionary genealogy of genes: Non-supervised Orthologous Groups

ENOG5032TA0, Bacteria

The HOGENOM Database of Homologous Genes from Fully Sequenced Organisms


Family and domain databases

Conserved Domains Database

cd12869, MqsR, 1 hit

Gene3D Structural and Functional Annotation of Protein Families

3.30.2310.40, 1 hit

Integrated resource of protein families, domains and functional sites

View protein in InterPro
IPR038493, MqsR_sf
IPR031451, MqsR_toxin

Pfam protein domain database

View protein in Pfam
PF15723, MqsR_toxin, 1 hit

<p>This section displays by default the canonical protein sequence and upon request all isoforms described in the entry. It also includes information pertinent to the sequence(s), including <a href="">length</a> and <a href="">molecular weight</a>. The information is filed in different subsections. The current subsections and their content are listed below:<p><a href='/help/sequences_section' target='_top'>More...</a></p>Sequencei

<p>This subsection of the <a href="">Sequence</a> section indicates if the <a href="">canonical sequence</a> displayed by default in the entry is complete or not.<p><a href='/help/sequence_status' target='_top'>More...</a></p>Sequence statusi: Complete.

Q46865-1 [UniParc]FASTAAdd to basket
« Hide
        10         20         30         40         50
60 70 80 90
Mass (Da):11,232
Last modified:November 1, 1996 - v1
<p>The checksum is a form of redundancy check that is calculated from the sequence. It is useful for tracking sequence updates.</p> <p>It should be noted that while, in theory, two different sequences could have the same checksum value, the likelihood that this would happen is extremely low.</p> <p>However UniProtKB may contain entries with identical sequences in case of multiple genes (paralogs).</p> <p>The checksum is computed as the sequence 64-bit Cyclic Redundancy Check value (CRC64) using the generator polynomial: x<sup>64</sup> + x<sup>4</sup> + x<sup>3</sup> + x + 1. The algorithm is described in the ISO 3309 standard. </p> <p class="publication">Press W.H., Flannery B.P., Teukolsky S.A. and Vetterling W.T.<br /> <strong>Cyclic redundancy and other checksums</strong><br /> <a href="">Numerical recipes in C 2nd ed., pp896-902, Cambridge University Press (1993)</a>)</p> Checksum:iD2662AB4DA8E111A

Sequence databases

Select the link destinations:

EMBL nucleotide sequence database


GenBank nucleotide sequence database


DNA Data Bank of Japan; a nucleotide sequence database

Links Updated
U28377 Genomic DNA Translation: AAA69190.1
U00096 Genomic DNA Translation: AAC76058.1
AP009048 Genomic DNA Translation: BAE77078.1

Protein sequence database of the Protein Information Resource


NCBI Reference Sequences

NP_417494.1, NC_000913.3
WP_000415584.1, NZ_SSZK01000023.1

Genome annotation databases

Ensembl bacterial and archaeal genome annotation project

AAC76058; AAC76058; b3022
BAE77078; BAE77078; BAE77078

Database of genes from NCBI RefSeq genomes


KEGG: Kyoto Encyclopedia of Genes and Genomes


Pathosystems Resource Integration Center (PATRIC)


<p>This section provides links to proteins that are similar to the protein sequence(s) described in this entry at different levels of sequence identity thresholds (100%, 90% and 50%) based on their membership in UniProt Reference Clusters (<a href="">UniRef</a>).<p><a href='/help/similar_proteins_section' target='_top'>More...</a></p>Similar proteinsi

<p>This section is used to point to information related to entries and found in data collections other than UniProtKB.<p><a href='/help/cross_references_section' target='_top'>More...</a></p>Cross-referencesi

Sequence databases

Select the link destinations:
Links Updated
U28377 Genomic DNA Translation: AAA69190.1
U00096 Genomic DNA Translation: AAC76058.1
AP009048 Genomic DNA Translation: BAE77078.1
RefSeqiNP_417494.1, NC_000913.3
WP_000415584.1, NZ_SSZK01000023.1

3D structure databases

Select the link destinations:

Protein Data Bank Europe


Protein Data Bank RCSB


Protein Data Bank Japan

Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum

Protein-protein interaction databases

BioGRIDi4260831, 22 interactors
ComplexPortaliCPX-1084, MqsRA toxin-antitoxin complex
IntActiQ46865, 10 interactors

Proteomic databases


Genome annotation databases

EnsemblBacteriaiAAC76058; AAC76058; b3022
BAE77078; BAE77078; BAE77078

Organism-specific databases

EchoBASE - an integrated post-genomic database for E. coli


Phylogenomic databases

eggNOGiENOG5032TA0, Bacteria

Enzyme and pathway databases


Miscellaneous databases

Protein Ontology


Family and domain databases

CDDicd12869, MqsR, 1 hit
Gene3Di3.30.2310.40, 1 hit
InterProiView protein in InterPro
IPR038493, MqsR_sf
IPR031451, MqsR_toxin
PfamiView protein in Pfam
PF15723, MqsR_toxin, 1 hit

ProtoNet; Automatic hierarchical classification of proteins


MobiDB: a database of protein disorder and mobility annotations


<p>This section provides general information on the entry.<p><a href='/help/entry_information_section' target='_top'>More...</a></p>Entry informationi

<p>This subsection of the 'Entry information' section provides a mnemonic identifier for a UniProtKB entry, but it is not a stable identifier. Each reviewed entry is assigned a unique entry name upon integration into UniProtKB/Swiss-Prot.<p><a href='/help/entry_name' target='_top'>More...</a></p>Entry nameiMQSR_ECOLI
<p>This subsection of the 'Entry information' section provides one or more accession number(s). These are stable identifiers and should be used to cite UniProtKB entries. Upon integration into UniProtKB, each entry is assigned a unique accession number, which is called 'Primary (citable) accession number'.<p><a href='/help/accession_numbers' target='_top'>More...</a></p>AccessioniPrimary (citable) accession number: Q46865
Secondary accession number(s): Q2M9H8
<p>This subsection of the 'Entry information' section shows the date of integration of the entry into UniProtKB, the date of the last sequence update and the date of the last annotation modification ('Last modified'). The version number for both the entry and the <a href="">canonical sequence</a> are also displayed.<p><a href='/help/entry_history' target='_top'>More...</a></p>Entry historyiIntegrated into UniProtKB/Swiss-Prot: July 15, 1998
Last sequence update: November 1, 1996
Last modified: April 7, 2021
This is version 124 of the entry and version 1 of the sequence. See complete history.
<p>This subsection of the 'Entry information' section indicates whether the entry has been manually annotated and reviewed by UniProtKB curators or not, in other words, if the entry belongs to the Swiss-Prot section of UniProtKB (<strong>reviewed</strong>) or to the computer-annotated TrEMBL section (<strong>unreviewed</strong>).<p><a href='/help/entry_status' target='_top'>More...</a></p>Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programProkaryotic Protein Annotation Program

<p>This section contains any relevant information that doesn't fit in any other defined sections<p><a href='/help/miscellaneous_section' target='_top'>More...</a></p>Miscellaneousi

Keywords - Technical termi

3D-structure, Reference proteome


  1. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
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