Thermodynamics of RNA-RNA binding

Area of Science:

• Molecular Biology
• Bioinformatics
• Computational Biology

Background:

• Accurate prediction of RNA-RNA binding energies is essential for understanding RNA interference (RNAi), microRNA-mRNA interactions, and antisense mechanisms.
• RNA-RNA interactions involve energy costs for binding site opening and energy gains from hybridization.

Purpose of the Study:

• To extend the partition function approach for RNA secondary structures to compute unpaired probabilities.
• To utilize these probabilities for determining RNA-RNA binding free energies and assessing RNAi efficiency.

Main Methods:

• Developed an extension of the standard partition function algorithm.
• Computed probabilities Pu[i, j] for sequence intervals [i, j] being unpaired.
• Applied these probabilities to calculate binding free energies for short RNA oligomers to mRNA targets.

Main Results:

• The computed unpaired probabilities Pu[i, j] serve as significant determinants of local target site accessibility in RNAi.
• Binding free energies were rigorously determined for short oligomers binding to large mRNA targets.
• RNAi efficiency showed a strong correlation with the calculated binding energies of siRNAs to their mRNA targets.

Conclusions:

• The extended partition function approach provides a robust method for predicting RNA-RNA binding energies.
• This method accurately predicts RNAi efficiency by correlating it with siRNA-mRNA binding energies.
• The computational resource requirements are comparable to standard partition function calculations.