Fluorescent probing for RNA molecules by an unnatural base-pair system

Area of Science:

• Molecular Biology
• Biochemistry
• Biophysics

Background:

• Fluorescent labeling is crucial for studying nucleic acids in research and medicine.
• Existing methods may lack site-specificity or require complex procedures.
• Understanding RNA structure and dynamics is essential for biological processes.

Purpose of the Study:

• To develop an efficient method for site-specific fluorescent labeling of RNA.
• To introduce a novel fluorescent base analog, 2-amino-6-(2-thienyl)purine (s), into RNA.
• To utilize an unnatural base pair system for controlled incorporation of the fluorescent analog.

Main Methods:

• Site-specific incorporation of the fluorescent ribonucleoside triphosphate of s into RNA using T7 RNA polymerase.
• Utilizing an unnatural base pair between s and pyrrole-2-carbaldehyde (Pa) in DNA templates.
• Amplification of DNA templates containing Pa using PCR with Ds, another pairing partner of Pa.

Main Results:

• Efficient site-specific incorporation of the fluorescent base analog s into RNA was achieved.
• The fluorescent intensity of s varied with the local structural environment in RNA.
• Characteristic fluorescent profiles were observed for labeled RNA hairpins and tRNA molecules.
• The system demonstrated sensitivity to temperature and Mg2+ concentration.

Conclusions:

• The s-Pa and Ds-Pa unnatural base pair system offers a powerful tool for site-specific fluorescent probing of RNA.
• This method enables detailed investigation of local structural features and dynamics in 3D RNA molecules.
• The system facilitates the study of intra- and intermolecular interactions within RNA structures.