DNA modifications on pyrimidine nucleobases play diverse roles in biology such as protection of bacteriophage DNA from enzymatic cleavage, however, their role in the regulation of transcription is underexplored. We have designed and synthesized a series of uracil 2'-deoxyribonucleosides and 5'-O-triphosphates (dNTPs) bearing diverse modifications at position 5 of nucleobase, including natural nucleotides occurring in bacteriophages, α-putrescinylthymine, α-glutaminylthymine, 5-dihydroxypentyluracil, and methylated or non-methylated 5-aminomethyluracil, and non-natural 5-sulfanylmethyl- and 5-cyanomethyluracil. The dNTPs bearing basic substituents were moderate to poor substrates for DNA polymerases, but still useful in primer extension synthesis of modified DNA. Together with previously reported epigenetic pyrimidine nucleotides, they were used for the synthesis of diverse DNA templates containing a T7 promoter modified in the sense, antisense or in both strands. A systematic study of the in vitro transcription with T7 RNA polymerase showed a moderate positive effect of most of the uracil modifications in the non-template strand and some either positive or negative influence of modifications in the template strand. The most interesting modification was the non-natural 5-cyanomethyluracil which showed significant positive effect in transcription.

• Publikační typ
• časopisecké články MeSH

Five 2'-deoxyribonucleoside triphosphates (dNTPs) derived from epigenetic pyrimidines (5-methylcytosine, 5-hydroxymethylcytosine, 5-formylcytosine, 5-hydroxymethyluracil, and 5-formyluracil) were prepared and systematically studied as substrates for nine DNA polymerases in competition with natural dNTPs by primer extension experiments. The incorporation of these substrates was evaluated by a restriction endonucleases cleavage-based assay and by a kinetic study of single nucleotide extension. All of the modified pyrimidine dNTPs were good substrates for the studied DNA polymerases that incorporated a significant percentage of the modified nucleotides into DNA even in the presence of natural nucleotides. 5-Methylcytosine dNTP was an even better substrate for most polymerases than natural dCTP. On the other hand, 5-hydroxymethyl-2'-deoxyuridine triphosphate was not the best substrate for SPO1 DNA polymerase, which naturally synthesizes 5hmU-rich genomes of the SPO1 bacteriophage. The results shed light onto the possibility of gene silencing through recycling and random incorporation of epigenetic nucleotides and into the replication of modified bacteriophage genomes.

• MeSH
• 5-methylcytosin * MeSH
• deoxyribonukleosidy MeSH
• DNA-dependentní DNA-polymerasy metabolismus   MeSH
• DNA metabolismus   MeSH
• epigeneze genetická MeSH
• nukleotidy metabolismus   MeSH
• pyrimidinové nukleotidy * MeSH
• pyrimidiny MeSH
• restrikční enzymy metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 5-methylcytosin * MeSH
• deoxyribonukleosidy MeSH
• DNA-dependentní DNA-polymerasy MeSH
• DNA MeSH
• nukleotidy MeSH
• pyrimidinové nukleotidy * MeSH
• pyrimidiny MeSH
• restrikční enzymy MeSH

We report proof of principle biomimetic switching of transcription in vitro through non-natural chemical reactions in the major groove of DNA templates. Photocaged DNA templates containing nitrobenzyl-protected 5-hydroxymethyluracil or - cytosine permitted no transcription with E. coli RNA polymerase (OFF state). Their irradiation with 400 nm light resulted in DNA templates containing hydroxymethylpyrimidines, which switched transcription ON with a higher yield (250-350%) compared to non-modified DNA. Phosphorylation of templates containing 5-hydroxymethyluracil (but not 5-hydroxymethylcytosine) then turned transcription OFF again. It is the first step towards artificial bioorthogonal chemical epigenetics.

• Publikační typ
• časopisecké články MeSH

A series of 2-alkylamino-2'-deoxyadenosine triphosphates (dATP) was prepared and found to be substrates for the Therminator DNA polymerase, which incorporated only one modified nucleotide into the primer. Using a template encoding for two consecutive adenines, conditions were found for incorporation of either one or two modified nucleotides. In all cases, addition of a mixture of natural dNTPs led to primer extension resulting in site-specific single modification of DNA in the minor groove. The allylamino-substituted DNA was used for the thiol-ene addition, whereas the propargylamino-DNA for the CuAAC click reaction was used to label the DNA with a fluorescent dye in the minor groove. The approach was used to construct FRET probes for detection of oligonucleotides.

• Klíčová slova
• DNA, fluorescent probes, nucleotides, oligonucleotides, polymerases,
• MeSH
• alylové sloučeniny chemie   MeSH
• deoxyadeninnukleotidy chemie   MeSH
• DNA chemie   MeSH
• fluorescenční barviva chemie   MeSH
• konformace nukleové kyseliny MeSH
• oligonukleotidy analýza   MeSH
• pargylin analogy a deriváty   chemie   MeSH
• propylaminy chemie   MeSH
• rezonanční přenos fluorescenční energie metody   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 2'-deoxyadenosine triphosphate MeSH Prohlížeč
• alylové sloučeniny MeSH
• deoxyadeninnukleotidy MeSH
• DNA MeSH
• fluorescenční barviva MeSH
• oligonukleotidy MeSH
• pargylin MeSH
• propargylamine MeSH Prohlížeč
• propylaminy MeSH

DNA templates containing a set of base modifications in the major groove (5-substituted pyrimidines or 7-substituted 7-deazapurines bearing H, methyl, vinyl, ethynyl or phenyl groups) were prepared by PCR using the corresponding base-modified 2'-deoxyribonucleoside triphosphates (dNTPs). The modified templates were used in an in vitro transcription assay using RNA polymerase from Bacillus subtilis and Escherichia coli Some modified nucleobases bearing smaller modifications (H, Me in 7-deazapurines) were perfectly tolerated by both enzymes, whereas bulky modifications (Ph at any nucleobase) and, surprisingly, uracil blocked transcription. Some middle-sized modifications (vinyl or ethynyl) were partly tolerated mostly by the E. colienzyme. In all cases where the transcription proceeded, full length RNA product with correct sequence was obtained indicating that the modifications of the template are not mutagenic and the inhibition is probably at the stage of initiation. The results are promising for the development of bioorthogonal reactions for artificial chemical switching of the transcription.

• MeSH
• Bacillus subtilis enzymologie   MeSH
• deoxyribonukleotidy biosyntéza   chemie   MeSH
• DNA řízené RNA-polymerasy metabolismus   MeSH
• DNA chemie   metabolismus   MeSH
• Escherichia coli enzymologie   MeSH
• genetická transkripce * MeSH
• genetické matrice MeSH
• konformace nukleové kyseliny MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• deoxyribonukleotidy MeSH
• DNA řízené RNA-polymerasy MeSH
• DNA MeSH

New redox labelling of DNA by an azido group which can be chemically transformed to nitrophenyltriazole or silenced to phenyltriazole was developed and applied to the electrochemical detection of DNA-protein interactions. 5-(4-Azidophenyl)-2'-deoxycytidine and 7-(4-azidophenyl)-7-deaza-2'-deoxyadenosine nucleosides were prepared by aqueous-phase Suzuki cross-coupling and converted to nucleoside triphosphates (dNTPs) which served as substrates for incorporation into DNA by DNA polymerase. The azidophenyl-modified nucleotides and azidophenyl-modified DNA gave a strong signal in voltammetric studies, at -0.9 V, due to reduction of the azido function. The Cu-catalyzed click reaction of azidophenyl-modified nucleosides or azidophenyl-modified DNA with 4-nitrophenylacetylene gave nitrophenyl-substituted triazoles, exerting a reduction peak at -0.4 V under voltammetry, whereas the click reaction with phenylacetylene gave electrochemically silent phenyltriazoles. The transformation of the azidophenyl label to nitrophenyltriazole was used for electrochemical detection of DNA-protein interactions (p53 protein) since only those azidophenyl groups in the parts of the DNA not shielded by the bound p53 protein were transformed to nitrophenyltriazoles, whereas those covered by the protein were not.

• Publikační typ
• časopisecké články MeSH