|Gene:||mqsR||Accession Numbers: G7572 (MetaCyc), b3022, ECK3013|
Species: Escherichia coli K-12 substr. MG1655
Component of: MqsA-MqsR antitoxin/toxin complex (summary available)
MqsR is a ribosome-independent mRNA interferase that inhibits protein synthesis by specifically cleaving mRNA at GCU sites [Yamaguchi09, ChristensenDals10]. The mRNA interferase activity is inhibited by interaction with MqsA [Yamaguchi09]. Expression of MqsR causes elongation of cells and reversible growth inhibition [Kasari10].
MqsR plays a role in controlling biofilm formation by inducing motility via the two-component regulatory system QseBC. MqsR links the AI-2 quorum sensing signal to biofilm formation [Gonzalez06].
A crystal structure of the MqsR-MqsA complex has been solved, showing that two molecules of MqsR bind to an MqsA dimer [Brown09a]. Binding of MqsR destabilizes the MqsA-DNA complex [Brown13]. MqsR adopts an RNase fold similar to YoeB and RelE. Key residues required for toxicity of MqsR have been identified by site-directed mutagenesis [Brown09a]. Amino acid changes that increase the stability of MqsR also increase its toxicity and effect on persister cell formation [Hong12].
Transcription of mqsR was found to be induced upon biofilm formation [Ren04], and deletion of mqsR decreases biofilm formation and abolishes motility [Gonzalez06]. Contrasting with this result, it was also reported that deletion of mqsR increases biofilm formation [Kim10b]. It was later found that the strain background influences MqsR activity [Kasari10]. mqsR is more highly expressed in persister cells than non-persisters, and overexpression of mqsR leads to growth arrest and increased tolerance to certain antibiotics [Shah06, Zhang08b]. Co-induction of mqsA expression rescues cell growth [Yamaguchi09, ChristensenDals10]. However, the opposite effect was reported by [Zhang08b]. Deletion of mqsRA decreases persister cell formation [Kim10c], while overexpression of MqsR induces expression of CspD [Kim10b] and increases persister cell formation via both toxins Hha and CspD [Kim10c]. An mqsR deletion strain shows decreased levels of persister cells only when the inoculum is from aged cultures [Luidalepp11].
The Lon protease is required for activation of the mqsRA locus. Transcription is induced by chloramphenicol treatment, amino acid starvation induced by serine hydroxamate, isoleucine starvation, and glucose starvation [ChristensenDals10].
Based on sequence similarity, MqsR was predicted to be a cyanide hydratase [Reed03].
MqsR: "motility quorum-sensing regulator" [Gonzalez06]
|Map Position: [3,166,270 <- 3,166,566]|
Molecular Weight of Polypeptide: 11.232 kD (from nucleotide sequence)
Unification Links: ASAP:ABE-0009925 , EchoBASE:EB2841 , EcoGene:EG13023 , EcoliWiki:b3022 , OU-Microarray:b3022 , PortEco:mqsR , PR:PRO_000023281 , Protein Model Portal:Q46865 , RefSeq:NP_417494 , RegulonDB:G7572 , SMR:Q46865 , String:511145.b3022 , UniProt:Q46865
Relationship Links: PDB:Structure:3HI2
|Biological Process:||GO:0017148 - negative regulation of translation
GO:0043488 - regulation of mRNA stability [Yamaguchi09]
GO:0044010 - single-species biofilm formation [Gonzalez06]
GO:0045892 - negative regulation of transcription, DNA-templated [Gonzalez06]
GO:0090502 - RNA phosphodiester bond hydrolysis, endonucleolytic [Yamaguchi09]
GO:0006351 - transcription, DNA-templated [UniProtGOA11a]
GO:0006355 - regulation of transcription, DNA-templated [UniProtGOA11a]
GO:0009372 - quorum sensing [UniProtGOA11a]
GO:0090305 - nucleic acid phosphodiester bond hydrolysis [UniProtGOA11a]
|Molecular Function:||GO:0004521 - endoribonuclease activity
GO:0005515 - protein binding [Yamaguchi09]
GO:0004518 - nuclease activity [UniProtGOA11a]
GO:0004519 - endonuclease activity [UniProtGOA11a]
GO:0016787 - hydrolase activity [UniProtGOA11a]
|MultiFun Terms:||cell processes → motility, chemotaxis, energytaxis (aerotaxis, redoxtaxis etc)|
|regulation → type of regulation → posttranscriptional → translation attenuation and efficiency|
Enzymatic reaction of: mRNA interferase
EC Number: 3.1.-.-
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.
The reaction is physiologically favored in the direction shown.
Subunit of: MqsA-MqsR antitoxin/toxin complex
Species: Escherichia coli K-12 substr. MG1655
Subunit composition of
MqsA-MqsR antitoxin/toxin complex = [MqsA]2[MqsR]4
MqsA antitoxin of the MqsRA toxin-antitoxin system and DNA-binding transcriptional repressor = MqsA (extended summary available)
mRNA interferase, toxin of the MqsR-MqsA toxin-antitoxin system = MqsR (extended summary available)
Based on biophysical and crystallographic studies, it was shown that MqsR is not a transcription corepressor but instead functions to destabilize the MqsA-DNA complex. The MqsRA complex does not bind to DNA [Brown13]. This is the first toxin-antitoxin (TA) system identified where the toxin does not function as a transcriptional corepressor [Brown13].
Symmetry: Inverted Repeat
Peter D. Karp on Thu Jan 16, 2003:
Predicted gene function revised as a result of E. coli genome reannotation by Serres et al. [Serres01 ].
Markus Krummenacker on Tue Oct 14, 1997:
Gene object created from Blattner lab Genbank (v. M52) entry.
Brown09a: Brown BL, Grigoriu S, Kim Y, Arruda JM, Davenport A, Wood TK, Peti W, Page R (2009). "Three dimensional structure of the MqsR:MqsA complex: a novel TA pair comprised of a toxin homologous to RelE and an antitoxin with unique properties." PLoS Pathog 5(12);e1000706. PMID: 20041169
Brown13: Brown BL, Lord DM, Grigoriu S, Peti W, Page R (2013). "The Escherichia coli toxin MqsR destabilizes the transcriptional repression complex formed between the antitoxin MqsA and the mqsRA operon promoter." J Biol Chem 288(2);1286-94. PMID: 23172222
ChristensenDals10: Christensen-Dalsgaard M, Jorgensen MG, Gerdes K (2010). "Three new RelE-homologous mRNA interferases of Escherichia coli differentially induced by environmental stresses." Mol Microbiol 75(2);333-48. PMID: 19943910
Gonzalez06: Gonzalez Barrios AF, Zuo R, Hashimoto Y, Yang L, Bentley WE, Wood TK (2006). "Autoinducer 2 controls biofilm formation in Escherichia coli through a novel motility quorum-sensing regulator (MqsR, B3022)." J Bacteriol 188(1);305-16. PMID: 16352847
Kim10c: Kim Y, Wood TK (2010). "Toxins Hha and CspD and small RNA regulator Hfq are involved in persister cell formation through MqsR in Escherichia coli." Biochem Biophys Res Commun 391(1);209-13. PMID: 19909729
Luidalepp11: Luidalepp H, Joers A, Kaldalu N, Tenson T (2011). "Age of inoculum strongly influences persister frequency and can mask effects of mutations implicated in altered persistence." J Bacteriol 193(14);3598-605. PMID: 21602347
Yamaguchi09: Yamaguchi Y, Park JH, Inouye M (2009). "MqsR, a crucial regulator for quorum sensing and biofilm formation, is a GCU-specific mRNA interferase in Escherichia coli." J Biol Chem 284(42);28746-53. PMID: 19690171
Zhang08b: Zhang XS, Garcia-Contreras R, Wood TK (2008). "Escherichia coli transcription factor YncC (McbR) regulates colanic acid and biofilm formation by repressing expression of periplasmic protein YbiM (McbA)." ISME J 2(6);615-31. PMID: 18309357
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