Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.21.3 (deoxyribonuclease)
 1,528 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transcription by purified mammalian RNA polymerase II in vitro leads to extensive formation of DNA-RNA hybrids between nascent RNA and the template DNA strand. This is especially clear during transcription of 3'-extended (dC-tailed) DNA templates where the nontranscribed DNA strand is progressively displaced as transcription proceeds [Kadesch, T. R., & Chamberlin, M. J. (1982) J. Biol. Chem. 257, 5286-5295]. Addition of small amounts of a HeLa cell extract to such a transcription system enhances renaturation of the template DNA and displacement of the nascent RNA, as measured by the sensitivity of the RNA to pancreatic ribonuclease. Using this latter assay, we have purified a protein factor (renaturase) 250-fold from HeLa cell extracts using chromatography on DEAE-cellulose, DNA-cellulose, and hydroxylapatite. Renaturase preparations facilitate complete renaturation of the template DNA duplex during transcription by RNA polymerase II and lead to concurrent displacement of the nascent RNA. Current preparations are free from all but traces of deoxyribonuclease or ribonuclease. The active component has a molecular weight of about 30000 as estimated by preparative density gradient sedimentation. We have examined the structure of transcribing RNA polymerase II complexes in the presence and absence of renaturase, using the electron microscope and the Williams polylysine technique [Williams, R. C. (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 2311-2315]. In the presence of renaturase, the DNA template is fully renatured, and a ternary complex in which the nascent RNA is displaced during transcription is seen.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Studies on transcription of 3'-extended DNA templates by mammalian RNA polymerase II. Partial purification and characterization of a factor from HeLa cells that facilitates renaturation of the DNA template. 399 13

Linear simian virus 40 DNA has been transcribed in vitro with wheat germ RNA polymerase II. Transcription products have been fractionated on polyacrylamide gels and several discrete sized RNA bands are seen. The RNA band pattern is affected dramatically by deoxyribonuclease treatment during RNA isolation. This is because most of the RNA synthesized is covalently linked to DNA. This linkage has been demonstrated by density analysis in formaldehyde-CsCl gradients and by incorporation of alkali-stable ribonucleotides into DNA. The linear DNA templates transcribed were generated by treatment of circular DNA with restriction enzymes which, in addition to cutting once at a single primary site, were found also to produce single strand nicks at specific secondary sites. The discrete sized RNA bands observed result from initiation at these nicks and terminated at DNA ends. There are two modes of nick-dependent initiation. In one mode the 3'-hydroxyl terminus of the DNA at a single strand nick serves as a primer for the extension of an RNA chain. In a second mode de novo initiation of an RNA chain is promoted at the nick. RNAs which are not primed initiate predominantly with GTP. The catalytic action of wheat germ RNA polymerase II is similar to that of Escherichia coli core RNA polymerase which has also been shown to synthesize primarily RNA which is covalently linked to DNA.
 ...
PMID:Transcription of simian virus 40 DNA by wheat germ RNA polymerase II. Priming of RNA synthesis by the 3'-hydroxyl of DNA at single strand nicks. 624 89

Sen1p in Saccharomyces cerevisiae is a Type I DNA/RNA helicase. Mutations in the helicase domain perturb accumulation of diverse RNA classes, and Sen1p has been implicated in 3' end formation of non-coding RNAs. Using a combination of global and candidate-specific two hybrid screens, eight proteins were identified that interact with Sen1p. Interactions with three of the proteins were analyzed further: Rpo21p(Rpb1p), a subunit of RNA polymerase II, Rad2p, a deoxyribonuclease required in DNA repair, and Rnt1p (RNase III), an endoribonuclease required for RNA maturation. For all three interactions, the two-hybrid results were confirmed by co-immunoprecipitation experiments. Genetic tests designed to assess the biological significance of the interactions indicate that Sen1p plays functionally significant roles in transcription and transcription-coupled DNA repair. To investigate the potential role of Sen1p in RNA processing and to assess the functional significance of the Sen1p/Rnt1p interaction, we examined U5 snRNA biogenesis. We provide evidence that Sen1p functions in concert with Rnt1p and the exosome at a late step in 3' end formation of one of the two mature forms of U5 snRNA but not the other. The protein-protein and protein-RNA interactions reported here suggest that the DNA/RNA helicase activity of Sen1p is utilized for several different purposes in multiple gene expression pathways.
 ...
PMID:Multiple protein/protein and protein/RNA interactions suggest roles for yeast DNA/RNA helicase Sen1p in transcription, transcription-coupled DNA repair and RNA processing. 1512 1