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)

Treatment of hamster cells in culture with the DNA alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) induces DNA polymerase beta (beta-pol) gene expression and cellular levels of the enzyme. Transcriptional activity of a cloned beta-pol promoter in transient expression assays is also stimulated. Among the requirements for these responses are methylation damage to genomic DNA, cellular cAMP-dependent protein kinase, and the ATF/CREB site of the cloned beta-pol promoter. In the present study, HeLa cell nuclear extract from MNNG-treated cells was much more active in an in vitro transcription assay than nuclear extract from normal cells. By using an oligonucleotide affinity column to deplete the nuclear extract of ATF/CREB, we showed that the difference was due to ATF/CREB activator. Purified ATF/CREB activator from MNNG-treated cells was approximately 10-fold more active than ATF/CREB purified from normal cells as a transcriptional activator for the depleted nuclear extract. ATF/CREB in the extract from normal cells is known to activate in vitro transcription by increasing the rate of promoter clearance [Narayan, S., Widen, S. G., Beard, W. A., & Wilson, S. H. (1994) J. Biol. Chem. 269, 12755-12763]. With ATF/CREB from MNNG-treated cells, the amount of preinitiation complex formed was much greater than with ATF/CREB from normal cells, and the kinetics of both the closed to open preinitiation complex isomerization and promoter clearance were altered. These results indicate that the mechanism of transcriptional activation secondary to DNA alkylation damage is recruitment of more preinitiation complex and alteration of the kinetic scheme of transcription initiation.
 ...
PMID:DNA damage-induced transcriptional activation of a human DNA polymerase beta chimeric promoter: recruitment of preinitiation complex in vitro by ATF/CREB. 781 26

A molecular dynamics simulation has been carried out with DNA polymerase beta (beta pol) complexed with a DNA primer-template. The templating guanine at the polymerase active site was covalently modified by the carcinogenic metabolite of benzo[a]pyrene, (+)-anti-benzo[a]pyrene diol epoxide, to form the major (+)-trans-anti-benzo[a]pyrene diol epoxide covalent adduct. Thus, the benzo[a]pyrenyl moiety (BP) is situated in the single-stranded template at the junction between double- and single-stranded DNA. The starting structure was based on the X-ray crystal structure of the rat beta pol primer-template and ddCTP complex [Pelletier, H., Sawaya, M. R., Kumar, A., Wilson, S. H., and Kraut, J. (1994) Science 264, 1891-1903]. During the simulation, the BP and its attached templating guanine rearrange to form a structure in which the BP is closer to parallel with the adjacent base pair. In addition, the templating attached guanine is displaced toward the major groove side and access to its Watson-Crick edge is partly obstructed. This structure is stabilized, in part, by new hydrogen bonds between the BP and beta pol Asn279 and Arg283. These residues are within hydrogen bonding distance to the incoming ddCTP and templating guanine, respectively, in the crystal structure of the beta pol ternary complex. Site-directed mutagenesis has confirmed their role in dNTP binding, discrimination, and catalytic efficiency [Beard, W. A., Osheroff, W. P., Prasad, R., Sawaya, M. R., Jaju, M., Wood, T. G., Kraut, J., Kunkel, T. A., and Wilson, S. H. (1996) J. Biol. Chem. 271, 12141-12144]. The predominant biological effect of the BP is DNA polymerase blockage. Consistent with this biological effect, the computed structure suggests the possibility that the BP's main deleterious impact on DNA synthesis might result at least in part from its specific interactions with key polymerase side chains. Moreover, relatively modest movement of BP and its attached guanine, with some concomitant enzyme motion, is necessary to relieve the obstruction and permit the observed rare incorporation of a dATP opposite the guanine lesion.
 ...
PMID:Interactions between DNA polymerase beta and the major covalent adduct of the carcinogen (+)-anti-benzo[a]pyrene diol epoxide with DNA at a primer-template junction. 945 77