Chemoproteomic Identification of Blue-Light-Damaged Proteins

Visible
light, particularly in the blue region of the spectrum,
can cause cell dysfunction through the generation of singlet oxygen,
contributing to cellular aging and age-related pathologies. Although
photooxidation of nucleic acids, lipids, and amino acids has been
extensively studied, the magnitude and span of blue-light-induced
protein damages within proteome remain largely unknown. Herein we
present a chemoproteomic approach to mapping blue-light-damaged proteins
in live mammalian cells by exploiting a nucleophilic alkyne chemical
probe. A gene ontology enrichment analysis revealed that cell surface
proteins are more readily oxidized than other susceptible sets of
proteins, including mitochondrial proteins. In particular, the integrin
family of cell surface receptors (ITGs) was highly ranked in the mammalian
cells tested, including human corneal endothelial cells. The blue-light-oxidized
ITGB1 protein was functionally inactive in promoting cell adhesion
and proliferation, suggesting that the photodamage of integrins contributes
to the blue-light-induced cell dysfunction. Further application of
our method to various cells and tissues should lead to a comprehensive
analysis of light-sensitive proteins.