Citation:

Han, J., J. Fu, J. Sun, D. Hall, D. Yang, D. Blatz, K. Houck, C. Ng, J. Doering, C. LaLone, AND H. Peng. Quantitative Chemical Proteomics Reveals Interspecies Variations on Binding Schemes of L-FABP with Perfluorooctanesulfonate. Nature Communications. Nature Publishing Group, London, Uk, 55(13):9012-9023, (2021). https://doi.org/10.1021/acs.est.1c00509

Impact/Purpose:

Interspecies toxicity variation is a long-standing unresolved question for chemical hazard assessment, due to the incompatibility of traditional methodologies. In this study, the full potential of chemical proteomics was explored and a Quantitative Interspecies Thermal Shift Assay (QITSA) method for in-situ, quantitative, and medium-throughput investigation of chemical-protein interactions in cell and tissue samples across species was developed. A case example focused on the interaction of per- and polyfluoroalkyl substances (PFAS) and a key protein involved in bioaccumulation, liver fatty acid binding protein, was used to demonstrate the application of this methodology.

Description:

Evaluating interspecies toxicity variation is a long-standing challenge for chemical hazard assessment. This study developed a quantitative interspecies thermal shift assay (QITSA) for in situ, quantitative, and modest-throughput investigation of chemical-protein interactions in cell and tissue samples across species. By using liver fatty acid binding protein (L-FABP) as a case study, the QITSA method was benchmarked with six per- and polyfluoroalkyl substances, and thermal shifts (ΔTm) were inversely related to their dissociation constants (R2 = 0.98). The QITSA can also distinguish binding modes of chemicals exemplified by palmitic acid. The QITSA was applied to determine the interactions between perfluorooctanesulfonate (PFOS) and L-FABP in liver cells or tissues from humans, mice, rats, and zebrafish. The largest thermal stability enhancement by PFOS was observed for human L-FABP followed by the mouse, rat, and zebrafish. While endogenous ligands were revealed to partially contribute to the large interspecies variation, recombinant proteins were employed to confirm the high binding affinity of PFOS to human L-FABP, compared to the rat and mouse. This study implemented an experimental strategy to characterize chemical-protein interactions across species, and future application of QITSA to other chemical contaminants is of great interest.

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