Distributions of bubble lifetimes and bubble lengths in DNA

Area of Science:

• Molecular Biology
• Biophysics
• Computational Chemistry

Background:

• DNA bubble formation and dynamics are critical for various biological processes, including replication and transcription.
• The influence of DNA sequence composition, specifically guanine-cytosine (GC) and adenine-thymine (AT) content, on bubble dynamics is not fully understood.
• Existing models may not fully capture sequence-dependent interactions affecting DNA stability.

Purpose of the Study:

• To investigate the distribution of DNA bubble lifetimes and lengths using molecular dynamics simulations.
• To elucidate the impact of GC/AT content on DNA bubble characteristics.
• To compare the performance of the standard Peyrard-Bishop-Dauxois (PBD) model with an extended version (ePBD) incorporating sequence-dependent stacking interactions.

Main Methods:

• Extensive molecular dynamics simulations employing the PBD and ePBD models.
• Analysis of bubble lifetime and length distributions across DNA sequences with varying GC/AT content.
• Development and application of base pair-dependent thresholds for defining nucleotide separation.

Main Results:

• Bubble lifetime distributions were accurately fitted by stretched exponential functions, decreasing with bubble length and GC content.
• Bubble length distributions also followed stretched exponential functions, with longer bubbles being more probable in AT-rich sequences.
• The ePBD model demonstrated a higher propensity for generating more numerous and longer-lived DNA bubbles compared to the PBD model.

Conclusions:

• DNA bubble dynamics are significantly modulated by sequence composition, favoring longer lifetimes and occurrences in AT-rich regions.
• The ePBD model provides a more comprehensive representation of DNA bubble behavior due to its inclusion of sequence-dependent stacking.
• Understanding these sequence-dependent dynamics is essential for predicting DNA stability and function.