Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.7 (DNA polymerase)
17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human cells from 13 different individuals were fused to mouse and rat cells producing abundant type C viral particles. The results demonstrate that incorporation of active DNA polymerase (reverse transcriptase) into mature type C particles is suppressed in many of the hybrid clones but not in the parental mouse cell clones. This low particle-associated DNA polymerase phenotype was a heritable trait for over 100 cell generations but reversion to a high particle-associated DNA polymerase phenotype was possible. In contrast, no evidence for suppression of viral p30 antigen was found. These results suggest that human cells contain a factor(s) capable of interfering with the normal maturation of the mouse retrovirus DNA polymerase protein; however, it was not possible to assign this function to any of 20 different human chromosomes tested. It is suggested that these somatic cell hybrids may be useful in examining individual events in retrovirus packaging and release.
...
PMID:Regulation of expression of type C virion DNA polymerase (reverse transcriptase) in human x mouse and human x rat hybrid cells. 9

Cells cultured from the breast muscles of 11 to 12-day-old chick embryos were infected in the undifferentiated mitotic myoblast stage or in the terminally differentiated non-mitotic myotube stage with one of two DNA viruses, vaccinia and herpes simplex virus type 1 (HSV-1). DNA synthesis was measured and production ov virus-specific DNA detected in cells infected as myoblasts or myotubes by isotope labelling, autoradiographic and buoyant density centrifugation techniques. Furthermore, fully fused myotubes resemble myoblasts in their ability to support productive infection by these DNA viruses although DNA replication and nuclear division have ceased in myotubes and only minimum levels of host-cell DNA polymerase activity are present.
...
PMID:Replication of animal viruses in differentiating muscle cells: vaccinia and herpes simplex virus type 1. 21 53

The activity of 2 nonmitochondrial forms of DNA polymerase, designated DNA polymerases alpha and beta, was investigated during liver regeneration in regimented rats. In accord with Barbiroli and Potter, we observed that regimentation of rats with respect to temperature, light and darkness, and availability of food resolves the DNA synthesis response to partial hepatectomy into 2 peaks, one occurring at a fixed time after operation and the other entrained by the environmental conditions. The peaks can be fused or separated depending on the timing of the operation. For this study, operation times were selected to give both patterns of DNA synthesis as measured by the uptake of radioactive thymidine into DNA. For both operation times, DNA polymerase activity in the nuclear extract correlated temporally and qualitatively with radioactive thymidine uptake into DNA. At the times of maximal DNA synthesis and polymerase activity, the DNA polymerase was purified from extracts of isolated nuclei. DNA polymerase alpha represented 70% and DNA polymerase beta represented 30% of the recovered activity from the nuclear extract. This is in agreement with the previous observation in nonregimented rats that DNA polymerase alpha is the major activity in nuclei during liver regeneration. For both operation times, DNA polymerase activity in the postmicrosomal fraction was sedimentable and increased 3 to 4 times above the level observed with this same fraction from normal rat liver. This activity was shown to be due to DNA polymerase alpha only with this subcellular fraction. DNA polymerase alpha activity with this fraction peaked 4 to 6 hr after the time of maximal radioactive thymidine incorporation into DNA. DNA polymerase activity in the microsome fraction did not change significantly after partial hepatectomy. This activity has been shown to represent DNA polymerase beta. Prior administration of cycloheximide and actinomycin abolished the rise in DNA polymerase alpha activity in the nucleus and postmicrosomal fraction. Hydroxyurea did not prevent the rise in DNA polymerase alpha activity with those subcellular fractions but did inhibit over 90% of the uptake of radioactive thymidine into DNA. These data suggest, but do not prove, that DNA polymerase alpha activity is induced in response to the stimulus(i) for liver regeneration.
...
PMID:Induction of DNA polymerase alpha during liver regeneration in rats on controlled feeding schedules. 126 Jul 44

We have previously described a mutant hepatitis B virus (HBV) with a fused X-C open reading frame (ORF) resulting from a single nucleotide insertion in the X-C overlapping region. A stably transformed cell line producing HBV particles, HepG2-K8, was established by transfecting the human hepatoma cell line HepG2 with a plasmid carrying four tandem repeats of the mutant HBV genome. The virus particles secreted into the culture medium were characterized by density gradient centrifugation and electron microscopy. The particles, similar to Dane particles by morphology and density, contained the mature HBV genome and endogenous DNA polymerase activity. Six HBV-specific transcripts of 4.0, 3.5, 2.2, 2.1, 1.2 and 0.9 kb were detected in HepG2-K8 cells by Northern blot analysis. cDNA cloning and sequence analysis of X mRNA showed that an elongated X ORF encoding 193 amino acids was created by a frameshift mutation in the 3'-terminal region of the wild-type X ORF and that the formation of an in-frame termination codon (TAA) resulted from polyadenylation. This elongated X gene product exerted transcriptional trans-activation.
...
PMID:Replication of a mutant hepatitis B virus with a fused X-C reading frame in hepatoma cells. 132 98

A plasmid carrying the 5'-flanking region (-1852 to +33 with respect to the transcription initiation site) of the mouse DNA polymerase beta gene fused with the chloramphenicol acetyltransferase (CAT) gene was cotransfected into mouse N18TG2 cells with adenovirus type 12 E1 genes-expressing plasmids. Expression of E1A gene products resulted in the elevation of the CAT expression by 3 to 7 folds, but that of E1B gene product was much less effective. RNase protection analysis revealed that the activation by E1A was at the transcription process. Both the 13S E1A and the 12S E1A activated the DNA polymerase beta gene promoter, indicating that the activation domain of E1A is in a common region(s) of 13S and 12S E1A products. The major target sequence of E1A was mapped within the 10 base pair-region (-30 to -20) of the DNA polymerase beta gene promoter, which overlapped with the palindromic sequence known as the ATF(CREB)/E4F-binding consensus. The results suggest that the palindromic sequence is essential for E1A-induced transcriptional activation of the mouse DNA polymerase beta gene.
...
PMID:Activation of the mouse DNA polymerase beta gene promoter by adenovirus type 12 E1A proteins. 153 5

The Streptococcus pneumoniae polA gene was altered at various positions by deletions and insertions. The polypeptides encoded by these mutant polA genes were identified in S. pneumoniae. Three of them were enzymatically active. One was a fused protein containing the first 11 amino acid residues of gene 10 from coliphage T7 and the carboxyl-terminal two-thirds of pneumococcal DNA polymerase I; it possessed only polymerase activity. The other two enzymatically active proteins, which contained 620 and 351 amino acid residues from the amino terminus, respectively, lacked polymerase activity and showed only exonuclease activity. These two polymerase-deficient proteins and the wild-type protein were hyperproduced in Escherichia coli and purified. In contrast to the DNA polymerase I of Escherichia coli but similar to the corresponding enzyme of Thermus aquaticus, the pneumococcal enzyme appeared to lack 3'-to-5' exonuclease activity. The 5'-to-3' exonuclease domain was located in the amino-terminal region of the wild-type pneumococcal protein. This exonuclease activity excised deoxyribonucleoside 5'-monophosphate from both double- and single-stranded DNAs. It degraded oligonucleotide substrates to a decameric final product.
...
PMID:Streptococcus pneumoniae DNA polymerase I lacks 3'-to-5' exonuclease activity: localization of the 5'-to-3' exonucleolytic domain. 154 39

The killer plasmid k1 of Kluyveromyces lactis has terminal inverted repeats of 202 base pairs (bp). The left terminal repeat is contiguous to the transcribed open reading frame, ORF1, which is supposed to code for a DNA polymerase. A 266-bp fragment (called Pk1) containing most of the terminal repeat sequence was isolated and examined for promoter activity. Pk1 was fused, in either original or inversed orientation, with a promoter-less lacZ gene of E coli and a promoter-less G418 resistance gene of Tn903. These fusions were introduced into a pKD1-derived circular vector, and transformed into a lactose-negative (lac4), and a G418-sensitive K lactis host. Lac+ and G418-resistant transformants were obtained with either orientation of Pk1. The promoter activity of Pk1 fragment was independent of the presence or absence of killer plasmids. It is not known whether Pk1 can also function bidirectionally on the natural k1 plasmid. The possible functions of Pk1 for killer plasmid gene expression and plasmid replication are discussed.
...
PMID:Promoter activity associated with the left inverted terminal repeat of the killer plasmid k1 from yeast. 166 Jul 26

Screening of a Mycobacterium tuberculosis genomic DNA library in the lambda gt11 expression vector was carried out by using, as probes, sera from tuberculous patients and murine monoclonal antibody H61.3 recognizing a mycobacterial 35-kilodalton protein present only on the M. tuberculosis complex. The recombinant beta-galactosidase-fused protein present in the crude lysate induced the proliferation of T lymphocytes from patients with tuberculous pleuritis. As the recombinant insert contains an internal EcoRI restriction site, it was possible to identify two fragments, one proximal to the lacZ gene and 1.7 kilobases (kb) in size and the other distal to the lacZ gene and 2.2 kb in size. Southern blot analysis showed that both of them hybridized with the genomic DNA from M. tuberculosis and M. bovis but not with the DNA from other mycobacterial species. To perform extensive immunological studies, the amount of beta-galactosidase-fused protein being very low, we fused the 1.7-kb fragment to the N-terminal part of the gene coding for the DNA polymerase of bacteriophage MS2 in the expression vector pEx34. The fusion protein was partially purified, and subsequent Western blotting (immunoblotting) and T-cell proliferation experiments confirmed the presence of B- and T-cell mycobacterial epitopes. Furthermore, to isolate the chromosomal region containing the 35-kilodalton gene, we constructed another mycobacterial genomic library in the lambda 2001 vector by cloning 15 to 20 kb of foreign DNA. Screening of this library was carried out by using 1.7- and 2.2-kb recombinant fragments as probes. Restriction maps of some clones isolated were determined.
...
PMID:Identification of a 35-kilodalton Mycobacterium tuberculosis protein containing B- and T-cell epitopes. 168 20

Mitotic chromosome condensation is normally dependent on the previous completion of replication. Caffeine spectacularly deranges cell cycle controls after DNA polymerase inhibition or DNA damage; it induces the condensation, in cells that have not completed replication, of fragmented nuclear structures, analogous to the S-phase prematurely condensed chromosomes seen when replicating cells are fused with mitotic cells. Caffeine has been reported to induce S-phase condensation in cells where replication is arrested, by accelerating cell cycle progression as well as by uncoupling it from replication; for, in BHK or CHO hamster cells arrested in early S-phase and given caffeine, condensed chromosomes appear well before the normal time at which mitosis occurs in cells released from arrest. However, we have found that this apparent acceleration depends on the technique of synchrony and cell line employed. In other cells, and in synchronized hamster cells where the cycle has not been subjected to prolonged continual arrest, condensation in replication-arrested cells given caffeine occurs at the same time as normal mitosis in parallel populations where replication is allowed to proceed. This caffeine-induced condensation is therefore "premature" with respect to the chromatin structure of the S-phase nucleus, but not with respect to the timing of the normal cycle. Caffeine in replication-arrested cells thus overcomes the restriction on the formation of mitotic condensing factors that is normally imposed during DNA replication, but does not accelerate the timing of condensation unless cycle controls have previously been disturbed by synchronization procedures.
...
PMID:Caffeine overcomes a restriction point associated with DNA replication, but does not accelerate mitosis. 216 52

The tau and gamma subunits of DNA polymerase III holoenzyme are both products of the dnaX gene. Since tau and gamma are required as stoichiometric components of the replicative complex, a mechanism must exist for the cell to coordinate their synthesis and ensure that both subunits are present in an adequate quantity and ratio for assembly. We have proposed that gamma is produced by a translational frameshift event. In this report, we describe the use of dnaX-lacZ fusions in all three reading frames to demonstrate that gamma, the shorter product of dnaX, is generated by ribosomal frameshifting to the -1 reading frame of the mRNA within an oligo(A) sequence that is followed by a sequence predicted to form a stable secondary structure. Immediately after frameshifting a stop codon is encountered, leading to translational termination. Mutagenesis of the oligo(A) sequence abolishes frameshifting, and partial disruption of the predicted distal secondary structure severely impairs the efficiency. Comparison of the expression of lacZ fused to dnaX distal to the site of frameshifting in the -1 and 0 reading frames indicates that the efficiency of frameshifting is approximately 40%.
...
PMID:The gamma subunit of DNA polymerase III holoenzyme of Escherichia coli is produced by ribosomal frameshifting. 218 90


1 2 3 4 5 6 7 8 9 10 Next >>

---