Chemoproteomic Approach for Identifying Nuclear Arsenite-binding Proteins

Trivalent arsenic [As(III)], the predominant environmental form, poses significant health risks, including cancer, diabetes, and cardiovascular and neurodegenerative diseases, through contaminated food and water ingestion. Studies have explored As(III) toxicity mechanisms, particularly its displacement of Zn(II) in zinc-binding proteins, but identifying direct As(III)-binding proteins remains crucial. Given the nucleic acid binding capacity of many zinc-binding proteins, we hypothesized that nuclear As(III)-binding proteins could reveal key toxicity targets. Using a quantitative proteomics approach, we performed affinity pull-down with a biotin-As(III) probe on nuclear protein lysate. We identified splicing factor 1 (SF1) as a direct As(III)-binding protein and demonstrated that this interaction modulates mRNA splicing in human cells.