Interactions between Extracellular DNA and Perfluoroalkyl Acids (PFAAs) Decrease the Bioavailability of PFAAs in...

Area of Science:

• Environmental Chemistry
• Molecular Biology
• Toxicology

Background:

• Perfluoroalkyl acids (PFAAs) are widespread environmental pollutants.
• Significant amounts of extracellular DNA are found alongside PFAAs in ecosystems.
• The interaction between PFAAs and DNA remains poorly understood.

Purpose of the Study:

• To investigate the binding interactions between various PFAAs and DNA.
• To elucidate the binding affinities and mechanisms of PFAA-DNA interactions.
• To assess the impact of PFAA-DNA binding on PFAA bioavailability.

Main Methods:

• Isothermal titration calorimetry (ITC) to determine binding affinities.
• Spectroscopic techniques to identify interaction sites on DNA bases.
• Computational simulations (molecular dynamics and quantum chemical calculations) to explore interaction forces.

Main Results:

• Specific binding affinities for PFHxA, PFOA, PFNA, and PFOS with DNA were quantified, showing strong interactions (10^4–10^5 L/mol).
• PFAA binding affinities to DNA were significantly higher than to human serum albumin.
• Interactions primarily occurred with DNA bases, particularly thymine, mediated by hydrogen bonds and van der Waals forces.
• PFAA-DNA binding was shown to decrease PFAA bioavailability in plant seedlings.

Conclusions:

• PFAAs exhibit significant binding affinities for DNA, suggesting a potential mechanism for their environmental fate.
• The binding involves specific interactions with DNA bases and is driven by hydrogen bonds and van der Waals forces.
• DNA binding reduces the bioavailability of PFAAs, influencing their uptake and effects in organisms like plants.