Organotellurium Probes Enable One-step Single-cell Analysis of Post-translational Modification

Protein prenylation is a widespread post-translational modification (PTM) that regulates membrane association and signaling; dysregulation of this process leads to a variety of diseases. Metabolic labeling with probes containing bioorthogonal functionality has revolutionized the study of many protein modifications, including prenylation. However, that approach requires two steps, including metabolic incorporation and subsequent bioorthogonal reaction to install chemical reporters. Here, we present the development and application of tellurium-containing isoprenoid analogues that can be incorporated through a single enzymatic step and enable the direct quantification of prenylation at the single-cell level by mass cytometry. This robust methodology was examined in a variety of cell lines and used to show that prenylation levels are perturbed in autophagy-deficient L6 cells, a model for certain features of aging. Modification of tellurium-labeled proteins through the oxidation-controlled strain-promoted tellurophene-alkyne cycloaddition reaction also enabled the identification of prenylation targets by chemical proteomics. This methodology bridges proteomic and multiplexed single-cell analyses, opening up promising avenues for exploring a variety of post-translational modifications.