Secondary structure content of the HDV ribozyme in 95% formamide

Area of Science:

• Molecular Biology
• Biochemistry
• RNA Structure

Background:

• The Hepatitis Delta Virus (HDV) ribozyme exhibits unique self-cleaving activity in denaturing formamide solutions.
• Understanding the structural basis for this activity is crucial for comprehending RNA catalysis.

Purpose of the Study:

• To investigate whether the conserved tertiary structure of the HDV ribozyme in formamide solutions underlies its catalytic function.
• To quantify the structural integrity of the HDV ribozyme in varying formamide concentrations.

Main Methods:

• Time-resolved fluorescence spectroscopy was used to monitor Ethidium Bromide (EB) binding.
• EB binding served as an estimate of ribozyme double helical content.
• The method was calibrated using oligonucleotides and denaturing solvents, paralleling NMR and UV measurements.

Main Results:

• HDV ribozyme precursor and product RNAs remain structured up to 24 M formamide (95% w/w).
• The HDV ribozyme demonstrated significantly greater structural retention in formamide compared to other investigated RNA sequences.
• DNA analogs of the HDV ribozyme lost structure below 15 M formamide.

Conclusions:

• The HDV ribozyme's structural integrity in high formamide concentrations is an intrinsic property of its RNA sequence.
• This intrinsic structure is likely responsible for its unique catalytic activity under denaturing conditions.