Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have determined the nucleotide sequence of the polC gene of Bacillus subtilis which codes for DNA polymerase III. Our recent analysis has revealed that the gene comprises 4311 nucleotides, from the start to the stop codon, 306 nucleotides more than we reported earlier. The plasmid reported by us and by N.C. Brown's laboratory contained a sequence at the end of the gene which is not related to the polC region of B. subtilis. We have isolated the rest of the gene, the sequence of which is presented in this paper. The new stop codon is followed by a hyphenated palindromic sequence of 13 nucleotides. The C-terminus of the coding region contains the novel mutation, dnaF, which results in a defect in the initiation of replication due to a change in the codon TCC to TTC (serine to phenylalanine). The hypermutator mutation mut-1 is due to two point mutations in the 3' to 5' exonuclease domain, the proof reading function. The codon changes are GGA to GAA (glycine to glutamic acid) and AGC to AAC (serine to asparagine). The elongation defective mutation, polC26, affecting the catalytic site that adds nucleotides to the growing chain, is due to a change in the codon GTC to GAC (valine to aspartic acid). It is separated from the mutation reported earlier, azp-12, by 306 nucleotides. Knowing the locations of the mutational sites allowed us to deduce the domains of the gene and the enzyme it encodes, and permitted us to present a precise map of the gene at the molecular level.
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PMID:Genetic structure and domains of DNA polymerase III of Bacillus subtilis. 184 Jun 38

The 31mer 5'-TCA ACG CTA GAA TTC GGA TCC ATC GCT TGG T, the complementary 33mer 5'-CCA AGC GAT GGA TCC GAA TTC TAG CGT TGA GAT, the 40mer 5'-GGC CAG GAT GGT GAA GAA TTC GAT CCG GTA CGT AGC TAA G, and the complementary 42mer 5'-TAC TTA GCT ACG TAC CGG ATC GAA TTC TTC ACC ATC CTG GCC were synthesized and their reactivity towards EcoRI was studied. It was found that the 31mer and the 40mer were cleaved at a comparable rate to the 31mer-33mer hybrid and the 40mer-42mer hybrid, respectively. The rate of cleavage of the 33mer and the 42mer was an order of magnitude lower. To rule out possible intermolecular duplex formation, the 33mer was immobilized on cellulose by ligation and labeled with alpha 32P-dCTP using Klenow fragment of E. coli DNA polymerase. EcoRI cleaved this immobilized oligomer into specific fragments.
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PMID:Cleavage of single stranded oligonucleotides by EcoRI restriction endonuclease. 302 89

DR6 is a complex allele family composed of at least 16 different alleles. Although 25% of Koreans express DR6 alleles, this allele family has not been well studied in the population. DNA samples obtained from 252 unrelated individuals were screened by PCR using Taq DNA polymerase and a DRB1 group-specific PCR primer set that amplifies the polymorphic second exon of DR3, DR11, and DR6 DRB1 alleles. To identify the DR6 allelic frequencies in this population, PCR-positive samples were further analyzed by dot-blot hybridization using digoxigenin-labeled SSOPs. In this process, a new DRB1 allele was identified by its unique hybridization pattern and was further characterized by direct sequencing after PCR. The new DRB1 sequence is similar to DRB1*1101, differing at codon 47 (TAC[Tyr]/TTC[Phe]) and at codon 58 (GCC[Ala]/GAG[Glu]). Based on sequence comparisons as well as its DRB3 and DQ associations, the new allele may have arisen by a gene conversion event from DRB1*1101. The resultant DR molecule bears DR6 serologic determinants as determined by serologic typing and, based on sequence, is probably a DR13 and not a DR14 allele. These data suggest that the DR11 allele has frequently acted as a recipient gene in the gene conversion events that created the subfamily of DR13 alleles, DRB1*1303, *1304, *1305, and the new allele described here.
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PMID:DR6 in Koreans. DR11 frequently acts as a recipient gene to create DR13 alleles. 830 Apr 8

Triplet repeat tracts occur throughout the human genome. Expansions of a (GAA)(n)/(TTC)(n) repeat tract during its transmission from parent to child are tightly associated with the occurrence of Friedreich's ataxia. Evidence supports DNA slippage during DNA replication as the cause of the expansions. DNA slippage results in single-stranded expansion intermediates. Evidence has accumulated that predicts that hairpin structures protect from DNA repair the expansion intermediates of all of the disease-associated repeats except for those of Friedreich's ataxia. How the latter repeat expansions avoid repair remains a mystery because (GAA)(n) and (TTC)(n) repeats are reported not to self-anneal. To characterize the Friedreich's ataxia intermediates, we generated massive expansions of (GAA)(n) and (TTC)(n) during DNA replication in vitro using human polymerase beta and the Klenow fragment of Escherichia coli polymerase I. Electron microscopy, endonuclease cleavage, and DNA sequencing of the expansion products demonstrate, for the first time, the occurrence of large and growing (GAA)(n) and (TTC)(n) hairpins during DNA synthesis. The results provide unifying evidence that predicts that hairpin formation during DNA synthesis mediates all of the disease-associated, triplet repeat expansions.
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PMID:Hairpin formation in Friedreich's ataxia triplet repeat expansion. 1244 36

To determine the tissue specificity of the potential mutations in DNA polymerase beta (pol beta), alterations in the pol beta were examined in breast, prostate, and colorectal primary tumors. The pol beta is known to contribute to mammalian base excision repair and replication. Similar to colorectal cancer, a high occurrence of mutations as 87-bp deletion in the catalytic domain of the pol beta removing 29 amino acids was observed in breast cancer. Contrary to breast and colorectal tumors, a low occurrence of mutation as a single base (T) deletion at the position coding for amino acid 181 of the pol beta was associated with prostate cancer. The missing T changed the codon from TTC to TCA (phenylalanine to serine), causing a frame shift.
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PMID:Mutations in DNA-polymerase-Beta occur in breast, prostate and colorectal tumors. 2155 60

Primases use single-stranded (ss) DNAs as templates to synthesize short oligoribonucleotide primers that initiate lagging strand DNA synthesis or reprime DNA synthesis after replication fork collapse, but the origin of this activity in the mitochondria remains unclear. Herein, we show that the Saccharomyces cerevisiae mitochondrial RNA polymerase (Rpo41) and its transcription factor (Mtf1) is an efficient primase that initiates DNA synthesis on ssDNA coated with the yeast mitochondrial ssDNA-binding protein, Rim1. Both Rpo41 and Rpo41-Mtf1 can synthesize short and long RNAs on ssDNA template and prime DNA synthesis by the yeast mitochondrial DNA polymerase Mip1. However, the ssDNA-binding protein Rim1 severely inhibits the RNA synthesis activity of Rpo41, but not the Rpo41-Mtf1 complex, which continues to prime DNA synthesis efficiently in the presence of Rim1. We show that RNAs as short as 10-12 nt serve as primers for DNA synthesis. Characterization of the RNA-DNA products shows that Rpo41 and Rpo41-Mtf1 have slightly different priming specificity. However, both prefer to initiate with ATP from short priming sequences such as 3'-TCC, TTC, and TTT, and the consensus sequence is 3'-Pu(Py)2-3 Based on our studies, we propose that Rpo41-Mtf1 is an attractive candidate for serving as the primase to initiate lagging strand DNA synthesis during normal replication and/or to restart stalled replication from downstream ssDNA.
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PMID:The Yeast Mitochondrial RNA Polymerase and Transcription Factor Complex Catalyzes Efficient Priming of DNA Synthesis on Single-stranded DNA. 2731 15