Gene Symbol: marR
Description: transcriptional repressor of multiple antibiotic resistance
Alias: ECK1523, JW5248, cfxB, inaR, soxQ
Species: Escherichia coli str. K-12 substr. MG1655

Top Publications

  1. Olofsson S, Marcusson L, Strömbäck A, Hughes D, Cars O. Dose-related selection of fluoroquinolone-resistant Escherichia coli. J Antimicrob Chemother. 2007;60:795-801 pubmed
    ..Mixed cultures of susceptible wild-type and isogenic single (gyrA S83L) or double (gyrA S83L, Delta marR) fluoroquinolone-resistant mutants were exposed to fluoroquinolones for 24 h in an in vitro kinetic model...
  2. Ariza R, Cohen S, Bachhawat N, Levy S, Demple B. Repressor mutations in the marRAB operon that activate oxidative stress genes and multiple antibiotic resistance in Escherichia coli. J Bacteriol. 1994;176:143-8 pubmed
    ..Mutations at this locus can activate the marRAB operon, in which marR encodes a putative repressor of mar transcription and marA encodes a putative transcriptional activator of defense ..
  3. Perez Rueda E, Collado Vides J. Common history at the origin of the position-function correlation in transcriptional regulators in archaea and bacteria. J Mol Evol. 2001;53:172-9 pubmed
    ..Two of these repressor families (MarR and AsnC) originated before the divergence of Archaea and Bacteria...
  4. Alekshun M, Levy S. The mar regulon: multiple resistance to antibiotics and other toxic chemicals. Trends Microbiol. 1999;7:410-3 pubmed
    ..The Mar phenotype is induced following exposure to a variety of chemicals with aromatic rings. ..
  5. Barbosa T, Levy S. Differential expression of over 60 chromosomal genes in Escherichia coli by constitutive expression of MarA. J Bacteriol. 2000;182:3467-74 pubmed
    ..Northern blot analysis of selected genes confirmed the results obtained with the macroarrays. The findings reveal that the mar locus mediates a global stress response involving one of the largest networks of genes described. ..
  6. Cohen S, Levy S, Foulds J, Rosner J. Salicylate induction of antibiotic resistance in Escherichia coli: activation of the mar operon and a mar-independent pathway. J Bacteriol. 1993;175:7856-62 pubmed
    ..However, salicylate can also activate an unidentified, mar-independent pathway(s) which engenders multiple antibiotic resistance. ..
  7. White D, Goldman J, Demple B, Levy S. Role of the acrAB locus in organic solvent tolerance mediated by expression of marA, soxS, or robA in Escherichia coli. J Bacteriol. 1997;179:6122-6 pubmed
    ..These findings strongly suggest that active efflux specified by the acrAB locus is linked to intrinsic organic solvent tolerance and to tolerance mediated by the marA, soxS, or robA gene product in E. coli. ..
  8. Keeney D, Ruzin A, McAleese F, Murphy E, Bradford P. MarA-mediated overexpression of the AcrAB efflux pump results in decreased susceptibility to tigecycline in Escherichia coli. J Antimicrob Chemother. 2008;61:46-53 pubmed
    ..Sequence analysis revealed a single nucleotide insertion in the open reading frame of the marR gene in less-susceptible strains of E. coli...
  9. Sulavik M, Gambino L, Miller P. The MarR repressor of the multiple antibiotic resistance (mar) operon in Escherichia coli: prototypic member of a family of bacterial regulatory proteins involved in sensing phenolic compounds. Mol Med. 1995;1:436-46 pubmed
    The marR gene of Escherichia coli encodes a repressor of the marRAB operon, a regulatory locus controlling multiple antibiotic resistance in this organism...

More Information


  1. Schumacher M, Brennan R. Structural mechanisms of multidrug recognition and regulation by bacterial multidrug transcription factors. Mol Microbiol. 2002;45:885-93 pubmed
    ..Here, we describe recent crystallographic studies on MarR, BmrR and QacR, three bacterial transcription regulators that are also multidrug-binding proteins...
  2. Bennik M, Pomposiello P, Thorne D, Demple B. Defining a rob regulon in Escherichia coli by using transposon mutagenesis. J Bacteriol. 2000;182:3794-801 pubmed
    ..that seven are transcriptionally activated by normal expression of Rob from the chromosomal rob gene (inaA, marR, aslB, ybaO, mdlA, yfhD, and ybiS). One gene, galT, was repressed by Rob...
  3. Harrison J, Tremaroli V, Stan M, Chan C, Vacchi Suzzi C, Heyne B, et al. Chromosomal antioxidant genes have metal ion-specific roles as determinants of bacterial metal tolerance. Environ Microbiol. 2009;11:2491-509 pubmed publisher
    ..characterized approximately 250 gene-metal combinations and identified that sodA, sodB, gor, trxA, gshA, grxA and marR have distinct roles in safeguarding or sensitizing cells to different toxic metal ions (Cr(2)O(7)(2-), Co(2+), Cu(2+..
  4. McEwen J, Silverman P. Chromosomal mutations of Escherichia coli that alter expression of conjugative plasmid functions. Proc Natl Acad Sci U S A. 1980;77:513-7 pubmed
    ..We have designated the chromosomal genes identified by these mutations as cpxA and cpxB; the mnemonic cpx signifying conjugative plasmid expression. ..
  5. Goldman J, White D, Levy S. Multiple antibiotic resistance (mar) locus protects Escherichia coli from rapid cell killing by fluoroquinolones. Antimicrob Agents Chemother. 1996;40:1266-9 pubmed
    ..The inducible mar locus appears to specify a novel antibactericidal mechanism which may play a role in the emergence of fluoroquinolone-resistant clinical E. coli isolates. ..
  6. Notka F, Linde H, Dankesreiter A, Niller H, Lehn N. A C-terminal 18 amino acid deletion in MarR in a clinical isolate of Escherichia coli reduces MarR binding properties and increases the MIC of ciprofloxacin. J Antimicrob Chemother. 2002;49:41-7 pubmed
    ..expression of the regulatory gene marA as a consequence of an 18 amino acid C-terminal deletion in the repressor MarR (MarR Delta)...
  7. Hachler H, Cohen S, Levy S. marA, a regulated locus which controls expression of chromosomal multiple antibiotic resistance in Escherichia coli. J Bacteriol. 1991;173:5532-8 pubmed
    ..These results indicate that the marA locus is needed for production of Mar mutants and is regulated, responding to at least two antibiotics to which it controls resistance. ..
  8. Martin R, Rosner J. Transcriptional and translational regulation of the marRAB multiple antibiotic resistance operon in Escherichia coli. Mol Microbiol. 2004;53:183-91 pubmed
    The marRAB multiple antibiotic resistance operon of Escherichia coli is autorepressed by MarR. MarR binds to two palindromic sequences in vitro: site I lies between and overlaps the -35 and -10 hexamers for RNA polymerase binding; site II ..
  9. Linde H, Notka F, Metz M, Kochanowski B, Heisig P, Lehn N. In vivo increase in resistance to ciprofloxacin in Escherichia coli associated with deletion of the C-terminal part of MarR. Antimicrob Agents Chemother. 2000;44:1865-8 pubmed
    ..A deletion of adenine (A) 1821 was found in marR of isolate EP2, which resulted in an 18-amino-acid C-terminal deletion in the MarR protein...
  10. Oethinger M, Kern W, Jellen Ritter A, McMurry L, Levy S. Ineffectiveness of topoisomerase mutations in mediating clinically significant fluoroquinolone resistance in Escherichia coli in the absence of the AcrAB efflux pump. Antimicrob Agents Chemother. 2000;44:10-3 pubmed
    ..Mutations in the target gene gyrA (DNA gyrase), the regulatory gene marR, and additional, as yet unidentified genes (genes that probably affect efflux mediated by the multidrug efflux pump ..
  11. McEwen J, Silverman P. Genetic analysis of Escherichia coli K-12 chromosomal mutants defective in expression of F-plasmid functions: identification of genes cpxA and cpxB. J Bacteriol. 1980;144:60-7 pubmed
  12. Martin R, Jair K, Wolf R, Rosner J. Autoactivation of the marRAB multiple antibiotic resistance operon by the MarA transcriptional activator in Escherichia coli. J Bacteriol. 1996;178:2216-23 pubmed vitro by using a minimal transcription system and in vivo by assaying beta-galactosidase synthesized from marR::lacZ fusions...
  13. Seoane A, Levy S. Characterization of MarR, the repressor of the multiple antibiotic resistance (mar) operon in Escherichia coli. J Bacteriol. 1995;177:3414-9 pubmed
    ..sensitive (3-fold lower at 42 than at 30 degrees C) and decreased 20-fold with the introduction of the gene for MarR. Structurally different compounds which induce the mar operon in wild-type cells reversed the MarR repression of ..
  14. Alekshun M, Levy S. Characterization of MarR superrepressor mutants. J Bacteriol. 1999;181:3303-6 pubmed
    b>MarR negatively regulates expression of the multiple antibiotic resistance (mar) locus in Escherichia coli...
  15. Wilkinson S, Grove A. Ligand-responsive transcriptional regulation by members of the MarR family of winged helix proteins. Curr Issues Mol Biol. 2006;8:51-62 pubmed
    The MarR (multiple antibiotic resistance regulator) family of prokaryotic transcriptional regulators includes proteins critical for control of virulence factor production, bacterial response to antibiotic and oxidative stresses and ..
  16. Grkovic S, Brown M, Skurray R. Regulation of bacterial drug export systems. Microbiol Mol Biol Rev. 2002;66:671-701, table of contents pubmed
    ..coli mar, expression of which is controlled by the MarA and MarR proteins...
  17. Silverman P, Nat K, McEwen J, Birchman R. Selection of Escherichia coli K-12 chromosomal mutants that prevent expression of F-plasmid functions. J Bacteriol. 1980;143:1519-23 pubmed
    ..At least six of these were also deficient as deoxyribonucleic acid donors. More than half of the mutants appear to be altered in peviously undetected chromosomal genes required for the expression of F-related cellular functions. ..
  18. Martin R, Nyantakyi P, Rosner J. Regulation of the multiple antibiotic resistance (mar) regulon by marORA sequences in Escherichia coli. J Bacteriol. 1995;177:4176-8 pubmed
  19. Martin R, Rosner J. Binding of purified multiple antibiotic-resistance repressor protein (MarR) to mar operator sequences. Proc Natl Acad Sci U S A. 1995;92:5456-60 pubmed
    ..Transcription of the operon is repressed in vivo by the marR-encoded protein, MarR, and derepressed by salicylate and certain antibiotics...
  20. Bina X, Perreten V, Levy S. The periplasmic protein MppA requires an additional mutated locus to repress marA expression in Escherichia coli. J Bacteriol. 2003;185:1465-9 pubmed
    ..Li and J. T. Park, J. Bacteriol. 181:4842-4847, 1999). We found that TP985 contained a previously unrecognized marR mutation which was responsible for the Mar phenotype...
  21. Alekshun M, Levy S, Mealy T, Seaton B, Head J. The crystal structure of MarR, a regulator of multiple antibiotic resistance, at 2.3 A resolution. Nat Struct Biol. 2001;8:710-4 pubmed
    b>MarR is a regulator of multiple antibiotic resistance in Escherichia coli...
  22. Pomposiello P, Bennik M, Demple B. Genome-wide transcriptional profiling of the Escherichia coli responses to superoxide stress and sodium salicylate. J Bacteriol. 2001;183:3890-902 pubmed
    ..A large number of PQ- and NaSal-responsive genes have no known function, suggesting that many adaptive metabolic changes that ensue after stress remain uncharacterized. ..
  23. Aono R. Improvement of organic solvent tolerance level of Escherichia coli by overexpression of stress-responsive genes. Extremophiles. 1998;2:239-48 pubmed
    ..coli, of which the organic solvent tolerance levels were improved. The mutants were defective in the marR gene encoding a repressor protein for the mar operon that is responsible for environmental stress factors...
  24. Cohen S, H chler H, Levy S. Genetic and functional analysis of the multiple antibiotic resistance (mar) locus in Escherichia coli. J Bacteriol. 1993;175:1484-92 pubmed
    ..mutations and the results of the complementation studies suggest that ORF125/144 encodes a repressor (designated MarR) which acts at marO...
  25. Domain F, Bina X, Levy S. Transketolase A, an enzyme in central metabolism, derepresses the marRAB multiple antibiotic resistance operon of Escherichia coli by interaction with MarR. Mol Microbiol. 2007;66:383-94 pubmed
    The Escherichia coli marRAB operon specifies two regulatory proteins, MarR (which represses) and MarA (which activates expression of the operon)...
  26. Kern W, Oethinger M, Jellen Ritter A, Levy S. Non-target gene mutations in the development of fluoroquinolone resistance in Escherichia coli. Antimicrob Agents Chemother. 2000;44:814-20 pubmed
  27. Hulo N, Sigrist C, Le Saux V, Langendijk Genevaux P, Bordoli L, Gattiker A, et al. Recent improvements to the PROSITE database. Nucleic Acids Res. 2004;32:D134-7 pubmed
    ..The latest version of PROSITE (release 18.17 of November 30, 2003) contains 1676 entries. The database is accessible at ..
  28. Alekshun M, Levy S. Regulation of chromosomally mediated multiple antibiotic resistance: the mar regulon. Antimicrob Agents Chemother. 1997;41:2067-75 pubmed
  29. Sulavik M, Gambino L, Miller P. Analysis of the genetic requirements for inducible multiple-antibiotic resistance associated with the mar locus in Escherichia coli. J Bacteriol. 1994;176:7754-6 pubmed
    ..Our findings indicate that regulated antibiotic resistance associated with this locus requires only the products of marR and marA, without any neighboring genes.
  30. Rosner J, Slonczewski J. Dual regulation of inaA by the multiple antibiotic resistance (mar) and superoxide (soxRS) stress response systems of Escherichia coli. J Bacteriol. 1994;176:6262-9 pubmed
    ..b>marR mutations that elevate marRAB transcription and engender multiple antibiotic resistance elevated inaA expression by ..
  31. Duval V, McMurry L, Foster K, Head J, Levy S. Mutational analysis of the multiple-antibiotic resistance regulator MarR reveals a ligand binding pocket at the interface between the dimerization and DNA binding domains. J Bacteriol. 2013;195:3341-51 pubmed publisher
    The Escherichia coli regulator MarR represses the multiple-antibiotic resistance operon marRAB and responds to phenolic compounds, including sodium salicylate, which inhibit its activity...
  32. Alekshun M, Levy S. Alteration of the repressor activity of MarR, the negative regulator of the Escherichia coli marRAB locus, by multiple chemicals in vitro. J Bacteriol. 1999;181:4669-72 pubmed
    b>MarR negatively regulates expression of the multiple antibiotic resistance operon (marRAB) in Escherichia coli...
  33. Alekshun M, Kim Y, Levy S. Mutational analysis of MarR, the negative regulator of marRAB expression in Escherichia coli, suggests the presence of two regions required for DNA binding. Mol Microbiol. 2000;35:1394-404 pubmed
    b>MarR, the negative regulator of the Escherichia coli multiple antibiotic resistance (marRAB) operon, is a member of a newly recognized family of regulatory proteins...
  34. Warner D, Levy S. Different effects of transcriptional regulators MarA, SoxS and Rob on susceptibility of Escherichia coli to cationic antimicrobial peptides (CAMPs): Rob-dependent CAMP induction of the marRAB operon. Microbiology. 2010;156:570-8 pubmed publisher
    ..Overexpression of marA, either in an antibiotic-resistant marR mutant or from a plasmid, decreased bacterial susceptibility to CAMPs...