Efficient synthesis of nucleic acids heavily modified with non-canonical ribose 2′-groups using a mutant T7 RNA polymerase (RNAP)

摘要

A T7 RNAP mutant (Y639F) which eliminates discrimination of the chemical character of the NTP ribose 2′-group, facilitates incorporation of non-canonical substrates into nucleic acids. However, transcripts containing a high percentage of non-canonical NMPs are poorly extended due to effects of the 2′-substituents on the transcript:template hybrid conformation. We tested the addition of compounds that stabilize A-type helix geometry to the reaction. High concentrations of polyamines, together with other changes in reaction conditions, greatly increased the synthesis of transcripts heavily substituted with non-canonical ribose 2′-groups. Template structures that facilitate promoter opening increased the efficiency of reactions where non-canonical substrates were incorporated during transcription of +1 to +6.