Twisting tetraplex DNA: A strand dynamics regulating i-motif function in diverse molecular crowding environments.

Area of Science:

• Biochemistry
• Molecular Biology
• Genetics

Background:

• Intercalated motif (i-motif) tetraplex DNA is vital for gene expression and disease.
• Limited knowledge exists on i-motif regulation within cells due to few identified binding proteins.
• Cellular molecular environments are hypothesized to be key regulators of i-motif formation and function.

Purpose of the Study:

• To investigate how diverse molecular crowding environments affect i-motif DNA stability and function.
• To elucidate the chemical mechanisms underlying i-motif regulation by molecular environments.

Main Methods:

• Systematic investigation using various polyethylene glycols (PEGs) and oligoethylene glycols (OEGs) to mimic cellular crowding.
• Quantitative validation through nuclear magnetic resonance (NMR) and molecular dynamics simulations.
• Assessment of hypochromicity changes and solution properties.

Main Results:

• PEGs and OEGs with six or more ethylene glycol units significantly stabilized the human telomere i-motif.
• Shorter PEGs/OEGs (less than six units) destabilized the i-motif.
• Cosolute-induced twisting dynamics altered the activation energy barrier for replication by a twofold magnitude.

Conclusions:

• Molecular environments, specifically crowding agents like PEGs and OEGs, play a significant role in regulating i-motif DNA stability and function.
• The length of ethylene glycol units in crowding agents dictates the stabilization or destabilization of i-motif structures.
• These findings suggest potential regulatory mechanisms for i-motif biological roles across cellular phases mediated by the molecular environment.