High-throughput protein target mapping enables accelerated bioactivity discovery for ToxCast and PFAS compounds

Area of Science:

• Environmental chemistry
• Toxicology
• Biochemistry

Background:

• Chemical pollution poses a global health risk, but toxicity mechanisms are often unknown.
• Identifying protein targets is crucial for understanding chemical toxicity and risk assessment.

Purpose of the Study:

• To systematically identify protein targets of prioritized chemical contaminants using an ultrahigh-throughput affinity-selection mass spectrometry (AS-MS) platform.
• To investigate the binding patterns of per- and polyfluoroalkyl substances (PFAS) with fatty acid-binding proteins (FABPs).

Main Methods:

• Applied an ultrahigh-throughput affinity-selection mass spectrometry (AS-MS) platform to screen 50 human proteins against 481 chemicals.
• Validated interactions with fatty acid-binding proteins (FABPs) using biochemical assays and X-ray crystallography.
• Assessed 24,050 potential protein-chemical interactions.

Main Results:

• Discovered 35 novel interactions involving 14 proteins, identifying FABPs as highly ligandable.
• Revealed distinct PFAS binding patterns: legacy PFAS bound selectively to FABP1, while newer perfluoroalkyl ether carboxylic acids (PFECAs) bound to all tested FABPs.
• X-ray crystallography showed that the ether group in alternative PFAS enhances molecular flexibility for FABP binding.

Conclusions:

• The AS-MS platform is effective for discovering novel protein targets beyond existing programs like ToxCast.
• Alternative PFAS exhibit a broader protein-binding spectrum than legacy PFAS, raising concerns about their potential as regrettable substitutes.
• Understanding these interactions is vital for assessing the health risks associated with emerging chemical contaminants.