Disease relevance of Polb

• A cDNA library of newborn rat brain poly(A)+ RNA in phage lambda gt11 was screened with a polyclonal antibody against chicken DNA polymerase beta [1].
• Expression of active rat DNA polymerase beta in Escherichia coli [2].
• Novikoff hepatoma stimulatory factor IV has been resolved from the DNA polymerase-beta on a single-stranded DNA-cellulose column and then purified to > 95% homogeneity on hydroxylapatite [3].
• The utility of structure-based combinatorial protein engineering (SCOPE) was demonstrated by its application to two distantly related members of the X-family of DNA polymerases: rat DNA polymerase beta (Pol beta) and African swine fever virus DNA polymerase X (Pol X) [4].
• DNA from T7 phage containing AP (apurinic/apyrimidinic) sites was repaired by the successive actions of three chromatin enzymes [AP endodeoxyribonuclease, DNAase IV (5'----3'-exodeoxyribonuclease) and DNA polymerase-beta] prepared from rat liver and T4-phage DNA ligase [5].

High impact information on Polb

• 2.3 A crystal structure of the catalytic domain of DNA polymerase beta [6].
• Excision of deoxyribose phosphate residues by DNA polymerase beta during DNA repair [7].
• In contrast, a majority of the endogenous DNA template sites for DNA polymerase beta (a presumptive repair enzyme) were closely associated with the peripheral nuclear lamina [8].
• MMS sensitivity of a cdc2-2 mutant at 20 degrees C is complemented by expression of mammalian DNA polymerase beta, an enzyme that fills single-strand gaps in duplex DNA in vitro and whose only known catalytic activity is polymerization of deoxyribonucleotides [9].
• The mutants possessing a split phenotype contain amino acid residue alterations within a putative nucleotide binding site of DNA polymerase beta [10].

Chemical compound and disease context of Polb

• When a primed template with 2-OH-Ade was treated with an exonuclease-deficient Klenow fragment of Escherichia coli DNA polymerase I (KFexo-), recombinant rat DNA polymerase beta (pol beta) or calf thymus DNA polymerase alpha (pol alpha), incorporation of dTMP and dAMP was observed [11].
• Changes in the expression pattern of the DNA polymerase beta gene during inhibition of spermatogenesis by busulphan and by temperature (artificial cryptorchidism) have been studied [12].

Biological context of Polb

• DNA polymerase beta, a member of the X family of DNA polymerases, is known to be involved in base excision repair [13].
• The D246V mutant of DNA polymerase beta misincorporates nucleotides: evidence for a role for the flexible loop in DNA positioning within the active site [13].
• Nucleotide sequence analysis of the cDNA and the genomic clones for rat DNA polymerase beta revealed the existence of a 1,005-base pair open reading frame capable of encoding a Mr = 38,269 polypeptide of 335 amino acid residues [14].
• A recombinant plasmid for expression of rat DNA polymerase beta was constructed in a plasmid/phage chimeric vector, pUC118, by an oligonucleotide-directed mutagenesis technique [2].
• These findings indicate that changes in the activity and expression of DNA polymerase beta are mediated via cAMP and the A-kinase system, and that phosphorylation of this enzyme is also involved in this expression [15].

Anatomical context of Polb

• The sequence Gly-Asp-Met-Asp, spanning positions 189-192 of rat DNA polymerase beta, is similar to the sequence motif Gly-Asp-Thr-Asp that is highly conserved in a number of replicative DNA polymerases from eukaryotic cells, viruses, and phages [16].
• Hormonal regulation of DNA polymerase beta activity and expression in rat adrenal glands and testes [15].
• Our results also suggest that the sites of nuclear DNA polymerase beta-driven DNA synthesis are uniquely sequestered within the characteristic peripheral heterochromatin shell and associated nuclear envelope structure, where they may potentially participate in DNA repair and/or replicative functions [8].
• An immunological procedure that uses antiserum against homogeneous calf thymus DNA polymerase beta to detect immunoreactive peptides on NaDodSO4/polyacrylamide gel electrophoresis demonstrates a high degree of conservation of protein sequence and molecular weight for this enzyme, from parastic protozoans to man [17].
• Using bovine testis crude nuclear extract, we have shown that G:U is repaired efficiently in vitro, and DNA polymerase beta (beta-pol) is responsible for the single nucleotide gap-filling synthesis (Singhal, R. K., Prasad, R., and Wilson, S. H.(1995) J. Biol. Chem. 270, 949-957) [18].

Associations of Polb with chemical compounds

• Mammalian DNA polymerase beta functions in the base excision DNA repair pathway filling in short patches (1-5 nt) in damaged DNA and removing deoxyribose 5'-phosphate from the 5'-side of damaged DNA [19].
• Structural relationship of lithocholic acid derivatives binding to the N-terminal 8-kDa domain of DNA polymerase beta [20].
• Aspartic acid residues at positions 190 and 192 of rat DNA polymerase beta are involved in primer binding [16].
• Similar effects are observed by knocking down DNA polymerase-beta or by using dideoxycytidine, a preferential inhibitor of this enzyme [21].
• Selective response of DNA polymerase beta to bleomycin-induced breaks in DNA [22].

Regulatory relationships of Polb

• A novel single-stranded DNA-binding protein from the Novikoff hepatoma which stimulates DNA polymerase beta. Purification and general characterization [23].

Other interactions of Polb

• DNA polymerase beta mRNA expression in rat testes was decreased by hypophysectomy and recovered with administration of gonadotropic hormone, suggesting that this enzyme is controlled at the mRNA level by this pituitary hormone [15].
• For this to happen, the conditions required are the presence of 5'-PO4 on the downstream primer and supplementation of aging neuronal extracts with DNA-ligase in addition to recombinant DNA polymerase beta [24].
• These results indicate that in young rats activities of epididymal DNA polymerase alpha and gamma and DNA topoisomerase I are partially, and that of DNA polymerase beta wholly, dependent on androgens and may provide a means of investigating the regulation of epididymal cell proliferation [25].

Analytical, diagnostic and therapeutic context of Polb

• Site-directed mutagenesis of recombinant rat DNA polymerase beta: involvement of arginine-183 in primer recognition [26].
• Interactions of rat DNA polymerase beta with a single-stranded (ss) DNA have been studied using the quantitative fluorescence titration technique [27].
• Crystallization of 31 kDa C-terminal fragment of rat DNA polymerase beta [28].
• However, at lower concentrations of DNA polymerase beta, the gap repair takes place quickly through gap filling followed by ligation to downstream primer, in an energy efficient manner [24].
• Monocytes and DNA polymerase beta were monitored by immunohistochemistry [29].

References