Disease relevance of polB

• The polB gene encoding deoxyribonucleic acid (DNA) polymerase II has been located close to a mutator gene, mutT1, in Escherichia coli [1].
• In this work, we present evidence that the two other DNA polymerases of E. coli, DNA polymerase I and DNA polymerase II, as well as polymerases of two phages, T4 (T4 pol) and T7 (T7 pol), undergo slippage in vitro, whereas DNA polymerase from another phage, Phi29, does not [2].

High impact information on polB

• A phenotype for enigmatic DNA polymerase II: a pivotal role for pol II in replication restart in UV-irradiated Escherichia coli [3].
• These observations suggest that repair-gap UV mutagenesis is performed by DNA polymerase III, and to a lesser extent by DNA polymerase II, by filling-in of a rare class of excision gaps that contain UV lesions [4].
• It also functions in similar reactions catalyzed by DNA polymerase II in combination with E. coli DNA binding protein and DNA elongation factors I and III [5].
• Amino acid sequence motifs essential to 3'-->5' exonuclease activity of Escherichia coli DNA polymerase II [6].
• Using amino acid sequence alignments, we predicted the putative active site of the 3'-->5' exonuclease of Escherichia coli DNA polymerase II [6].

Chemical compound and disease context of polB

• In separate experiments, E. coli was treated with HN2, and the relative sensitivity to killing was found to be as follows: wild type < polB < recA < polB recA approximately uvrA [7].
• Similar findings were reported by Sherman and Gefter using Escherichia coli DNA polymerase II and fd DNA (J. Mol. Biol. (1976) 103, 61-76) [8].
• Enhancement of DNA polymerase II activity in E. coli after treatment with N-methyl-N'-nitro-N-nitrosoguanidine [9].

Biological context of polB

• The Escherichia coli polB gene, which encodes DNA polymerase II, is regulated by the SOS system [10].
• We have purified the DNA polymerase II of Escherichia coli from the recombinant strain carrying the plasmid which encodes the polB gene [11].
• Following multiple passages of polB cells or prolonged starvation, a progressive loss of sensitivity to killing by peroxide was observed, suggesting that second-site suppressor mutations may be occurring with relatively high frequencies [12].
• Resistance to peroxide killing was restored following P1 transduction of polB cells to polB+ or by conjugation of polB cells with an F' plasmid carrying a copy of polB+ [12].
• DNA polymerase II (polB) is involved in a new DNA repair pathway for DNA interstrand cross-links in Escherichia coli [7].

Anatomical context of polB

• The apparent Km at 21 degrees C for gapped calf thymus DNA was 25 muM with Mn2+ and 125 muM with Mg2+ for DNA polymerase III, and 18 muM at 30 degrees C for DNA polymerase II with either Mn2+ or Mg2+ [13].

Associations of polB with chemical compounds

• The rate at which Lac+ mutations arose in Lac- cells subjected to selection for lactose utilization, a phenomenon known as adaptive mutation, was increased threefold in polB backgrounds and returned to wild-type rates when polB cells were transduced to polB+ [12].
• Novobiocin and nalidixic acid also inhibited synthesis, as did the omission of ATP, N-Ethylmaleimide, an inhibitor of DNA polymerase II and III activity, but not DNA polymerase I activity, also partially inhibited the synthetic reaction, as did chloramphenicol [14].
• No decrease in bypass of thymine glycol or cyclobutane pyrimidine dimers in the absence of DNA polymerase II was observed [15].
• The Mn2+-activated DNA polymerase II reaction requires K+ or spermidine, and the effects of monovalent cation and polyamine are additive [13].
• The total activity of DNA polymerases in polA1 cells (mostly DNA polymerase II) was not impaired for the phenethyl alcohol-treated cells and the reduction of the rate of DNA synthesis in vitro was ascribed to the reduction of the chromosomal template activity which was related to trypsin sensitive protein components [16].

Analytical, diagnostic and therapeutic context of polB

• Site-directed mutagenesis at D155A, E157A, D155A/E157A, D228A, Y330F, and D334A, which are in the predicted exonuclease active regions, specifically inactivated 3'-->5' exonucleolytic activity but not DNA-polymerizing activity of E. coli DNA polymerase II [6].
• Crystallization of DNA polymerase II from Escherichia coli [17].

References