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Gene Review

tolC  -  transport channel

Escherichia coli str. K-12 substr. MG1655

Synonyms: ECK3026, JW5503, colE1-i, mtcB, mukA, ...
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Disease relevance of tolC


High impact information on tolC

  • Thus, tolC is a critical virulence factor of F. tularensis in addition to its role in multidrug resistance, which suggests the presence of a functional type I secretion system [2].
  • In this study, we characterized two genes in the F. tularensis genome, tolC and a gene we term ftlC, whose products have high homology with the Escherichia coli TolC protein [2].
  • Neither tolC nor ftlC was required for replication of the live vaccine strain in murine bone marrow-derived macrophages [2].
  • The hasF gene was thus cloned from S. marcescens into an E. coli tolC mutant carrying hasD and hasE genes, by screening for a proteolytic phenotype on skimmed-milk plates. hasF encodes a protein sharing 74% identity with the E. coli TolC protein [5].
  • BepC fully complemented the resistance to drugs such as chloramphenicol and acriflavine but was incapable of restoring hemolysin secretion in the tolC mutant of E. coli [6].

Chemical compound and disease context of tolC

  • The raxC gene complemented an Escherichia coli tolC mutant for secretion of a double glycine-leader peptide confirming the function of raxC in type I secretion [7].
  • We observed energy-dependent ethidium efflux in cells of E. coli KAM32 possessing sdeXY and tolC [8].
  • When the wild-type E. coli tolC gene was introduced into a strain lacking the gene, TolC function was restored and the frequency of induction by MNNG became similar to that of the wild-type [9].

Biological context of tolC

  • This phenotype was not observed in tolC and rfaD cells in the same conditions [10].
  • Microarray and S1 mapping assays indicated that, in the presence of this constitutive mutant EvgS, the level of transcription increased for some MDR genes, including the drug efflux genes emrKY, yhiUV, acrAB, mdfA and tolC [11].
  • Transcription activation of tolC by the activated EvgS was, however, dependent on both EvgAS and PhoPQ (Mg(2+)-responsive two-component system), in agreement with the presence of the binding site (PhoP box) for the regulator PhoP in the tolC promoter region [11].
  • Mutations at this third locus, referred to as toc (topoisomerase one compensatory) mutations, do not behave as point mutations in transductional crosses and do not result in lowered DNA gyrase activity [12].
  • In contrast to the cistronic organization of the secretion genes in most other rtx operons, the hlyD and tolC genes were adjacent but unlinked to hlyB; neither locus was part of an operon containing genes encoding putative TOSS substrates [13].

Anatomical context of tolC

  • The inability to transfer STIp in the periplasm into the culture supernatant was restored by introduction of the tolC gene into the mutant cells [14].

Associations of tolC with chemical compounds

  • When a defective tolC gene was transferred to n-hexane- or cyclohexane-tolerant strains by P1 transduction, the organic solvent tolerance level was lowered dramatically to the decane-tolerant and nonane-sensitive level [15].
  • In contrast, introduction of a mutant tolC gene did not complement the TolC deficiency and the frequency of MNNG-induced mutations remained high [9].

Other interactions of tolC

  • The htrP gene was identified because its insertional inactivation by the Tn10 transposon results in the inability of E. coli to form colonies at temperatures above 37 degrees C and a slow growth phenotype at 30 degrees C. The htrP gene was cloned and mapped to 66.3 min on the E. coli genetic map, 4 kbp clockwise from the tolC gene [16].
  • Other outer membrane defective strains such as tolC, lpp, and rfa mutations are also altered in their outer membrane permeability [10].
  • Gene affected by mutation (mtcA or mtcB) in both mutants was cloned and its nucleotide (nt) sequence was determined [17].


  1. Nucleotide sequence of the tolC gene of Escherichia coli. Niki, H., Imamura, R., Ogura, T., Hiraga, S. Nucleic Acids Res. (1990) [Pubmed]
  2. Deletion of TolC orthologs in Francisella tularensis identifies roles in multidrug resistance and virulence. Gil, H., Platz, G.J., Forestal, C.A., Monfett, M., Bakshi, C.S., Sellati, T.J., Furie, M.B., Benach, J.L., Thanassi, D.G. Proc. Natl. Acad. Sci. U.S.A. (2006) [Pubmed]
  3. Identification of the Haemophilus influenzae tolC gene by susceptibility profiles of insertionally inactivated efflux pump mutants. Trepod, C.M., Mott, J.E. Antimicrob. Agents Chemother. (2004) [Pubmed]
  4. The eefABC multidrug efflux pump operon is repressed by H-NS in Enterobacter aerogenes. Masi, M., Pagès, J.M., Villard, C., Pradel, E. J. Bacteriol. (2005) [Pubmed]
  5. Cloning of the Serratia marcescens hasF gene encoding the Has ABC exporter outer membrane component: a TolC analogue. Binet, R., Wandersman, C. Mol. Microbiol. (1996) [Pubmed]
  6. The TolC Homologue of Brucella suis Is Involved in Resistance to Antimicrobial Compounds and Virulence. Posadas, D.M., Mart??n, F.A., Sabio Y Garc??a, J.V., Spera, J.M., Delpino, M.V., Baldi, P., Campos, E., Cravero, S.L., Zorreguieta, A. Infect. Immun. (2007) [Pubmed]
  7. Bacterial genes involved in type I secretion and sulfation are required to elicit the rice Xa21-mediated innate immune response. da Silva, F.G., Shen, Y., Dardick, C., Burdman, S., Yadav, R.C., de Leon, A.L., Ronald, P.C. Mol. Plant Microbe Interact. (2004) [Pubmed]
  8. An RND-type multidrug efflux pump SdeXY from Serratia marcescens. Chen, J., Kuroda, T., Huda, M.N., Mizushima, T., Tsuchiya, T. J. Antimicrob. Chemother. (2003) [Pubmed]
  9. Involvement of the drug efflux protein TolC in mutagenicity induced by MNNG or Trp-P-2. Takahashi, E., Okamoto, K., Arimoto, S., Yamanaka, H., Negishi, T. Mutat. Res. (2006) [Pubmed]
  10. Escherichia coli tol-pal mutants form outer membrane vesicles. Bernadac, A., Gavioli, M., Lazzaroni, J.C., Raina, S., Lloubès, R. J. Bacteriol. (1998) [Pubmed]
  11. Transcriptional regulation of drug efflux genes by EvgAS, a two-component system in Escherichia coli. Eguchi, Y., Oshima, T., Mori, H., Aono, R., Yamamoto, K., Ishihama, A., Utsumi, R. Microbiology (Reading, Engl.) (2003) [Pubmed]
  12. Genetic analysis of mutations that compensate for loss of Escherichia coli DNA topoisomerase I. Raji, A., Zabel, D.J., Laufer, C.S., Depew, R.E. J. Bacteriol. (1985) [Pubmed]
  13. Unusual genetic organization of a functional type I protein secretion system in Neisseria meningitidis. Wooldridge, K.G., Kizil, M., Wells, D.B., Ala'aldeen, D.A. Infect. Immun. (2005) [Pubmed]
  14. Need for TolC, an Escherichia coli outer membrane protein, in the secretion of heat-stable enterotoxin I across the outer membrane. Yamanaka, H., Nomura, T., Fujii, Y., Okamoto, K. Microb. Pathog. (1998) [Pubmed]
  15. Involvement of outer membrane protein TolC, a possible member of the mar-sox regulon, in maintenance and improvement of organic solvent tolerance of Escherichia coli K-12. Aono, R., Tsukagoshi, N., Yamamoto, M. J. Bacteriol. (1998) [Pubmed]
  16. The Escherichia coli htrP gene product is essential for bacterial growth at high temperatures: mapping, cloning, sequencing, and transcriptional regulation of htrP. Raina, S., Mabey, L., Georgopoulos, C. J. Bacteriol. (1991) [Pubmed]
  17. The Deinococcus radiodurans uvr A gene: identification of mutation sites in two mitomycin-sensitive strains and the first discovery of insertion sequence element from deinobacteria. Narumi, I., Cherdchu, K., Kitayama, S., Watanabe, H. Gene (1997) [Pubmed]
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