A series of adenosine triphosphate (ATP) derivatives bearing chloro, fluoro, amino, methyl, vinyl, and ethynyl groups at position 2 are synthesized and tested as substrates for RNA and DNA polymerases. The modified nucleotides work well in in vitro transcription with T7 RNA polymerase and primer extension (PEX) using engineered DNA polymerases (TGK, 2M) except for the bulkier 2-vinyl- and 2-ethynyl-ATP derivatives that give truncated products. However, in single nucleotide incorporation followed by PEX, they still can be used for site-specific incorporation of reactive modifications into RNA that can be further used for postsynthetic labeling through thiol-ene or Cu-catalyzed alkyne-azide cycloadditions reactions. All modified ATPs work in polyadenylation catalyzed by poly(A) polymerase to form long 3'-polyA tails containing the modifications that also can be used for labeling.

• Keywords
• DNA polymerases, RNA polymerases, click reactions, nucleosides triphosphates, nucleotides, polyA polymerase, thiol‐ene addition,
• MeSH
• Adenosine Triphosphate * chemical synthesis   chemistry   analogs & derivatives   metabolism   MeSH
• Cycloaddition Reaction MeSH
• DNA-Directed RNA Polymerases * metabolism   chemistry   MeSH
• DNA-Directed DNA Polymerase * metabolism   chemistry   MeSH
• RNA * chemistry   metabolism   MeSH
• Viral Proteins metabolism   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Adenosine Triphosphate * MeSH
• bacteriophage T7 RNA polymerase MeSH Browser
• DNA-Directed RNA Polymerases * MeSH
• DNA-Directed DNA Polymerase * MeSH
• RNA * MeSH
• Viral Proteins MeSH

Protein-RNA interactions play important biological roles and hence reactive RNA probes for cross-linking with proteins are important tools in their identification and study. To this end, we designed and synthesized 5'-O-triphosphates bearing a reactive squaramate group attached to position 5 of cytidine or position 7 of 7-deazaadenosine and used them as substrates for polymerase synthesis of modified RNA. In vitro transcription with T7 RNA polymerase or primer extension using TGK polymerase was used for synthesis of squaramate-modified RNA probes which underwent covalent bioconjugations with amine-linked fluorophore and lysine-containing peptides and proteins including several viral RNA polymerases or HIV reverse transcriptase. Inhibition of RNA-depending RNA polymerases from Japanese Encephalitis virus was observed through formation of covalent cross-link which was partially identified by MS/MS analysis. Thus, the squaramate-linked NTP analogs are useful building blocks for the synthesis of reactive RNA probes for bioconjugations with primary amines and cross-linking with lysine residues.

• Publication type
• Journal Article MeSH

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.

• Publication type
• Journal Article MeSH

Innovative approaches to controlled nucleobase-modified RNA synthesis are urgently needed to support RNA biology exploration and to synthesize potential RNA therapeutics. Here we present a strategy for enzymatic construction of nucleobase-modified RNA based on primer-dependent engineered thermophilic DNA polymerases - SFM4-3 and TGK. We demonstrate introduction of one or several different base-modified nucleotides in one strand including hypermodified RNA containing all four modified nucleotides bearing four different substituents, as well as strategy for primer segment removal. We also show facile site-specific or segmented introduction of fluorophores or other functional groups at defined positions in variety of RNA molecules, including structured or long mRNA. Intriguing translation efficacy of single-site modified mRNAs underscores the necessity to study isolated modifications placed at designer positions to disentangle their biological effects and enable development of improved mRNA therapeutics. Our toolbox paves the way for more precise dissecting RNA structures and functions, as well as for construction of diverse types of base-functionalized RNA for therapeutic applications and diagnostics.

• MeSH
• DNA-Directed DNA Polymerase * genetics   MeSH
• RNA, Messenger genetics   MeSH
• Nucleotides chemistry   MeSH
• RNA * genetics   chemistry   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• DNA-Directed DNA Polymerase * MeSH
• RNA, Messenger MeSH
• Nucleotides MeSH
• RNA * MeSH