Characterization of PFAS Binding Effects on Protein Structure Using Collision-Induced Unfolding

Area of Science:

• Environmental Chemistry
• Biochemistry
• Toxicology

Background:

• Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants with potential adverse health effects due to bioaccumulation.
• Understanding PFAS interactions with biological molecules, like proteins, is crucial for elucidating their toxicity mechanisms.
• Noncovalent complexation to proteins is a potential pathway for PFAS-induced cellular toxicity.

Purpose of the Study:

• To investigate the impact of PFAS binding on protein structure using collision-induced unfolding (CIU).
• To compare the structural effects of different PFAS molecules with varying chain lengths on a model protein.

Main Methods:

• Utilized cyclic ion mobility-mass spectrometry (cIM-MS) to perform collision-induced unfolding (CIU).
• Measured changes in protein size and shape as a function of activation energy to characterize unfolding pathways.
• Employed ubiquitin as a model protein and tested three related PFAS: PFBS, PFHxS, and PFOS.

Main Results:

• Observed qualitative and quantitative differences in ubiquitin unfolding influenced by the number of bound PFAS molecules.
• Demonstrated that PFAS chain length significantly impacts protein structural changes.
• Showcased the non-passive role of PFAS when associated with proteins.

Conclusions:

• CIU-cIM-MS provides a rapid and targeted method for analyzing noncovalent complexation between toxins and biological molecules.
• PFAS binding can induce distinct structural alterations in proteins, varying with PFAS properties.
• This approach aids in understanding potential PFAS toxicity mechanisms at a molecular level.