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Gene Review

dnaQ  -  DNA polymerase III epsilon subunit

Escherichia coli str. K-12 substr. MG1655

Synonyms: ECK0215, JW0205, mutD
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Disease relevance of dnaQ


High impact information on dnaQ

  • These observations suggest that the mismatch-repair deficiency of mutD strains results from a saturation of the mutHLS-mismatch-repair system by an excess of primary DNA replication errors due to the proofreading defect [4].
  • Twenty-one derivatives of a lambda::mini-Mu phage containing point mutations in the Mu attachment regions were isolated after mutD mutagenesis and selection for relief from Mu-specific replicative interference of lambda growth [5].
  • From beta-galactosidase levels it was estimated that the promoter for dnaQ is 5 times more active than that for rnh [1].
  • The region of the Escherichia coli chromosome coding for the mutD gene was cloned, mutD5 function resides on a 1.2-kilobase fragment coding for a 28-kilodalton (kDa) protein [6].
  • Transformation of mutD by a hybrid plasmid, pRD3, constructed from an EcoRI restriction fragment of E. coli and pBR322, cures mutD of its abnormally high mutation rate, and simultaneously restores its 3'-exonuclease activity [7].

Biological context of dnaQ

  • Deletion product analysis suggested that slipped mispairing, producing monomeric replicon products, may be preferentially increased in a dnaQ mutant and sister-strand exchange, producing dimeric replicon products, may be elevated in dnaE mutants [8].
  • All K-12 strains, obtained from collections, appear in the "off" form even when bearing mutations in mutS, mutD, or dnaQ which are known to enhance slip strand events between repetitive sequences [9].
  • Identification of the epsilon-subunit of Escherichia coli DNA polymerase III holoenzyme as the dnaQ gene product: a fidelity subunit for DNA replication [10].
  • A novel mutagenesis strategy was used to identify 23 dnaQ alleles that exhibit a mutator phenotype in vivo [11].
  • Here we report on the 1.6 kb (1 kb = 10(3) bases or base-pairs) sequence of the region coding for both genes, and the transcripts encoded by them. mutD codes for two transcripts, one of whose origins lies within the rnh structural gene [12].

Associations of dnaQ with chemical compounds

  • Deoxynucleosides bearing isoadenine (2-aminopurine) and isoguanine (2-hydroxy-6-aminopurine) showed a high mutagenic potency towards the recombinant strains, to an extent comparable to that of the most efficient mutator alleles (dnaQ) [13].
  • A host mutD mutation or thymine deprivation increases deletion frequency about 10-fold [14].
  • We then replaced each of the seven histidine codons in the mutD gene with glycine codons and found that in two cases, a strong mutator phenotype results [15].

Other interactions of dnaQ


Analytical, diagnostic and therapeutic context of dnaQ


  1. Structure and expression of the dnaQ mutator and the RNase H genes of Escherichia coli: overlap of the promoter regions. Maki, H., Horiuchi, T., Sekiguchi, M. Proc. Natl. Acad. Sci. U.S.A. (1983) [Pubmed]
  2. Mutator and antimutator effects of the bacteriophage P1 hot gene product. Chikova, A.K., Schaaper, R.M. J. Bacteriol. (2006) [Pubmed]
  3. Changing the substrate specificity of penicillin G acylase from Kluyvera citrophila through selective pressure. Roa, A., Garcia, J.L., Salto, F., Cortes, E. Biochem. J. (1994) [Pubmed]
  4. The extreme mutator effect of Escherichia coli mutD5 results from saturation of mismatch repair by excessive DNA replication errors. Schaaper, R.M., Radman, M. EMBO J. (1989) [Pubmed]
  5. Isolation of point mutations in bacteriophage Mu attachment regions cloned in a lambda::mini-Mu phage. Burlingame, R.P., Obukowicz, M.G., Lynn, D.L., Howe, M.M. Proc. Natl. Acad. Sci. U.S.A. (1986) [Pubmed]
  6. Structure and coding properties of a dominant Escherichia coli mutator gene, mutD. Cox, E.C., Horner, D.L. Proc. Natl. Acad. Sci. U.S.A. (1983) [Pubmed]
  7. The interaction of DNA polymerase III and the product of the Escherichia coli mutator gene, mutD. DiFrancesco, R., Bhatnagar, S.K., Brown, A., Bessman, M.J. J. Biol. Chem. (1984) [Pubmed]
  8. Enhanced deletion formation by aberrant DNA replication in Escherichia coli. Saveson, C.J., Lovett, S.T. Genetics (1997) [Pubmed]
  9. Reversible phase variation in the phnE gene, which is required for phosphonate metabolism in Escherichia coli K-12. Iqbal, S., Parker, G., Davidson, H., Moslehi-Rahmani, E., Robson, R.L. J. Bacteriol. (2004) [Pubmed]
  10. Identification of the epsilon-subunit of Escherichia coli DNA polymerase III holoenzyme as the dnaQ gene product: a fidelity subunit for DNA replication. Scheuermann, R., Tam, S., Burgers, P.M., Lu, C., Echols, H. Proc. Natl. Acad. Sci. U.S.A. (1983) [Pubmed]
  11. Dysfunctional proofreading in the Escherichia coli DNA polymerase III core. Lehtinen, D.A., Perrino, F.W. Biochem. J. (2004) [Pubmed]
  12. DNA sequence and coding properties of mutD(dnaQ) a dominant Escherichia coli mutator gene. Cox, E.C., Horner, D.L. J. Mol. Biol. (1986) [Pubmed]
  13. Human deoxycytidine kinase as a conditional mutator in Escherichia coli. Bouzon, M., Marlière, P. C. R. Acad. Sci. III, Sci. Vie (1997) [Pubmed]
  14. A simple technique for the isolation of deletion mutants of phage lambda. Sternberg, N., Hamilton, D., Enquist, L., Weisberg, R. Gene (1979) [Pubmed]
  15. Examination of the role of DNA polymerase proofreading in the mutator effect of miscoding tRNAs. Slupska, M.M., King, A.G., Lu, L.I., Lin, R.H., Mao, E.F., Lackey, C.A., Chiang, J.H., Baikalov, C., Miller, J.H. J. Bacteriol. (1998) [Pubmed]
  16. Specificity of Escherichia coli mutD and mutL mutator strains. Wu, T.H., Clarke, C.H., Marinus, M.G. Gene (1990) [Pubmed]
  17. The interaction of the Escherichia coli mutD and mutT pathways in the prevention of A:T-->C:G transversions. Fowler, R.G., Amutan, M.V., Isbell, R.J. Mutat. Res. (1992) [Pubmed]
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