Non-hydrogen-bonded base pairs for specific transcription

Area of Science:

• Synthetic biology
• Molecular biology
• Biochemistry

Background:

• Unnatural base pairs (UBPs) offer potential for novel RNA functionalities and genetic code expansion.
• Site-specific incorporation of modified nucleobases into RNA is crucial for creating advanced RNA molecules.

Purpose of the Study:

• To report a novel unnatural base pair for site-specific RNA transcription.
• To investigate the efficiency and fidelity of this UBP in transcription.
• To explore the utility of this UBP for fluorescence probing of RNA.

Main Methods:

• Utilized T7 RNA polymerase for transcription from DNA templates containing pyrrole-2-carbaldehyde (Pa).
• Incorporated unnatural bases 2-amino-6-(2-thienyl)purine (s) or 6-(2-thienyl)purine (s') into RNA.
• Assessed transcription efficiency and fidelity through comparative analysis with natural base pairings.

Main Results:

• Successfully demonstrated site-specific RNA transcription using the s-Pa and s'-Pa unnatural base pairs.
• Achieved high transcription efficiency and fidelity comparable to natural base pairings, despite minimal hydrogen bonding.
• Highlighted the significance of shape complementarity in base pairing during transcription.
• Showcased the utility of the fluorescent 's' base for site-specific RNA probing.

Conclusions:

• The s-Pa and s'-Pa unnatural base pairs are effective for site-specific RNA synthesis.
• Shape complementarity plays a key role in the fidelity of unnatural base pairing during transcription.
• This UBP system provides a valuable tool for fluorescence-based analysis of RNA molecules.