Disease relevance of dnaQ

• Structure and expression of the dnaQ mutator and the RNase H genes of Escherichia coli: overlap of the promoter regions [1].
• The Hot (homolog of theta) protein of bacteriophage P1 can substitute for the Escherichia coli DNA polymerase III theta subunit, as evidenced by its stabilizing effect on certain dnaQ mutants that carry an unstable polymerase III epsilon proofreading subunit (antimutator effect) [2].
• Escherichia coli (muT, mutD, Leu-) cells transformed with plasmid pYKD59 harbouring the pac gene encoding penicillin acylase (PA) from Kluyvera citrophila ATCC 21285 were exposed to environmental conditions that made expression of this enzyme essential for growth [3].

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

• Specificity of Escherichia coli mutD and mutL mutator strains [16].
• The interaction of the Escherichia coli mutD and mutT pathways in the prevention of A:T-->C:G transversions [17].

Analytical, diagnostic and therapeutic context of dnaQ

• To define further the role of the dnaQ gene, we have used two-dimensional gel electrophoresis to compare the labeled dnaQ gene product with purified polymerase III holoenzyme [10].

References