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Gene Review

marR  -  transcriptional repressor of multiple...

Escherichia coli str. K-12 substr. MG1655

Synonyms: ECK1523, JW5248, cfxB, inaR, soxQ
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Disease relevance of marR


High impact information on marR

  • The phenotype was linked to insertion sequence (IS) insertions in marR or acrR or unstable large tandem genomic amplifications which included acrAB and which were bordered by IS3 or IS5 sequences [2].
  • The gene encoding the ELISA-positive factor, cfxB, consisted of 375 nucleotides and was located downstream of an 852-nucleotide open reading frame, cfxA, with a 56-nucleotide intergenic space [3].
  • The cfxB gene was predicted to encode a 125-amino-acid polypeptide, which had 73.8 and 72.8% identities with the amino acid sequences of LTB and CTB, respectively [3].
  • Genetics and regulation of outer membrane protein expression by quinolone resistance loci nfxB, nfxC, and cfxB [4].
  • DNA sequence analysis showed that, like marR1, the other two mutations were alterations of marR: a 285-bp deletion in cfxB1 and a GC-->AT transition at codon 70 (Ala-->Thr) in soxQ1 [5].

Chemical compound and disease context of marR


Biological context of marR

  • In aerobiosis, activation of sodA transcription by SoxRS was compatible with CfxB activation or Fur repression, whereas cfxB and fur controls were mutually exclusive [7].
  • 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 genes against antibiotics and oxidants [5].


  1. Activation of oxidative stress genes by mutations at the soxQ/cfxB/marA locus of Escherichia coli. Greenberg, J.T., Chou, J.H., Monach, P.A., Demple, B. J. Bacteriol. (1991) [Pubmed]
  2. Increased Genome Instability in Escherichia coli lon Mutants: Relation to Emergence of Multiple-Antibiotic-Resistant (Mar) Mutants Caused by Insertion Sequence Elements and Large Tandem Genomic Amplifications. Nicoloff, H., Perreten, V., Levy, S.B. Antimicrob. Agents Chemother. (2007) [Pubmed]
  3. Cloning and characterization of genes encoding homologues of the B subunit of cholera toxin and the Escherichia coli heat-labile enterotoxin from clinical isolates of Citrobacter freundii and E. coli. Karasawa, T., Ito, H., Tsukamoto, T., Yamasaki, S., Kurazono, H., Faruque, S.M., Nair, G.B., Nishibuchi, M., Takeda, Y. Infect. Immun. (2002) [Pubmed]
  4. Genetics and regulation of outer membrane protein expression by quinolone resistance loci nfxB, nfxC, and cfxB. Hooper, D.C., Wolfson, J.S., Bozza, M.A., Ng, E.Y. Antimicrob. Agents Chemother. (1992) [Pubmed]
  5. Repressor mutations in the marRAB operon that activate oxidative stress genes and multiple antibiotic resistance in Escherichia coli. Ariza, R.R., Cohen, S.P., Bachhawat, N., Levy, S.B., Demple, B. J. Bacteriol. (1994) [Pubmed]
  6. Sequence and organization of pMAC, an Acinetobacter baumannii plasmid harboring genes involved in organic peroxide resistance. Dorsey, C.W., Tomaras, A.P., Actis, L.A. Plasmid (2006) [Pubmed]
  7. Interaction of six global transcription regulators in expression of manganese superoxide dismutase in Escherichia coli K-12. Compan, I., Touati, D. J. Bacteriol. (1993) [Pubmed]
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